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[Articles Home]  [Add Article]  

10-Pound 700-Watt Automatic Amplifer

Ignacy Misztal (NO9E) on June 6, 2008
View comments about this article!

We associate power amplifiers with large boxes generating tons of heat, whether transmitting or just standing by, and by soft to racket noise sources. Sometimes it seems that tube amplifiers changed little from Alpha 78A. Transistor amplifiers are often heavier and more expensive than amplifiers with tubes, and often they need a tuner.

In many aspects, 5lb radios available now are better than 20-30lb radios manufactured 20 yrs ago yet the new radios are much cheaper to manufacture. Isn't it time for amps to downsize and become cheaper?

A 10lb 700W amp would derive its low weight from no power transformers and high efficiency (=less cooling) possibly with high voltage transistors. The power supply would be switching but without a transformer, directly from 110V. 150V would be transformed to 100V by a buck design that needs only a single coil ( http://en.wikipedia.org/wiki/Buck_converter). Insulating the RF deck should be no problem with toroid transformers. RF would be generated by2 x SD3933 (350W, 100V, up to 70% efficiency; http://www.st.com/stonline/products/literature/ds/9966/sd3933.pdf). The output could be PI with switched components, like in automatic tuners. This would results in better matching to transistors per band resulting in higher efficiency, and it would make matching to higher SWR antennas (say <3:1) possible without extra components. Because of the push-pull circuit, the PI filter can operate with low Q, permitting the use of small capacitors and small toroid inductors.

The amp can be extensively computer protected and controlled. Some of the extra features could be automatic rematching at lower power, a different bias for CW, and completely shutting off the bias with no signal, all for higher efficiency and less heat generation. As opposed to a tube amp, there is no filament or transformer heating when in standby.

The 100V SD3933 seem more linear and efficient than low voltage transistors. It's very high gain can perhaps be used to generate feedback for low IMD. One can expect that higher voltage RF transistors would become available in the future. A 160V transistor would require no switching power supply at all.

There are many details missing and I am not an amplifier designer. Perhaps a switching PI filter would not eliminate high harmonics efficiently and something more would be needed. Perhaps a small addition would add an L-type tuner so that the amp would tune SWR > 10:1. Perhaps the 100V transistor is too brittle. ….

The motivation for this article comes from several experiences. In 1975 I homebrewed an 80W 10lb radio. It derived its 600V for 829B directly by doubling 220V. No problems except one had to guess which side of the power plug was the ground (the plug was two-prong symmetric). Most of my guesses were right, and I am still alive; insulating the power deck at that time was out of question. Second experience is with a 500W solid state amp. Despite abuse and no cooling fan (just large sink), only minor problems experienced in 10 years. Third experience is with a tube amp with eham rating of 4.8 made by a reputable US manufacturer. In two years, a few QSK board failures, a flashover, and a burnt band switch.

Member Comments:
This article has expired. No more comments may be added.
 
10-Pound 700-Watt Automatic Amplifer  
by KB9CRY on June 6, 2008 Mail this to a friend!
There are many details missing and I am not an amplifier designer


Exactly
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by AA8LL on June 6, 2008 Mail this to a friend!
If it's legal, dependable, and under $1000; I'll buy one. Easily switchable 120/240 for travel would be nice, too!
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K0BG on June 6, 2008 Mail this to a friend!
Missing? To say the least. Even with high voltage MOSFETs, it is difficult to achieve efficiencies greater than 50% or so, no matter the drain voltage. You eat up some in the filter bank, and you have to keep the device(s) within its (near) linear region, and you have to assure proper bias control, plus a few dozen more things.

The ALS-500 weights in at 7 pounds, so it is possible to build a SS amp that isn't too heavy. However, comparing the ALS-500 to an SGC SG500 which weights in at 21 pounds, is an apples/oranges argument.

Alan, KØBG
www.k0bg.com
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by WW5AA on June 6, 2008 Mail this to a friend!
The main problem is sales. The big amp makers can't make a volume profit on anything that sells for more than about $1500/2000. I would buy it right now if you could sell me a reliable kilo-watt, solid state, rig controlled amp for the price of an AL-80B. Good thought though, maybe some day.

73 de Lindy
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by NO9E on June 6, 2008 Mail this to a friend!
Sorry for the unfinished article. I submitted it, asked to withhold until rewritten, then had too many distractions.

The main idea is that a desirable amp be light, instant on, automatic and with built-in tuner. This can be accomplished by high efficiency and high voltage power MOSFETs, transformer-less 110V or even 220V power supply, and switched tuner circuits instead of bandpass filters. I know that many details are missing and critics can find faults everywhere.

New power MOSFETs (http://www.microsemi.com/catalog/parmlist.asp?P0_RFMKTID=31&APT=1&RF=1&P1_TYPE=RFMOS) operate at high voltages, have very high efficiency (up to 75% in class B), seem more linear than older devices, and have high gain. Out of 750W class transistors, ARF1500 (used by Tokyo Power 1.5 KW amp) operates at 125V, ARF1501 at 250V, ARF1505 at 300V and ARF1511 at 380V. Some of them can be fed directly from 110v, avoiding any need for power transformer. Some of them are advertised as class C only but they seem to have quite linear characteristics and with forward distortion (?) they possibly can be made linear.

For light amplifiers, one needs to recognize a design by k5and for a 1.5 KW 20lb amp (http://www.gare.co.uk/k5and/8877.htm). It was single band only and used a tube.

 
RE: 10-Pound 700-Watt Automatic Amplifer  
by SM0AOM on June 6, 2008 Mail this to a friend!
To make a reliable SS power amplifier, it takes a lot of protection circuitry. RF MOSFETS are quite tempermental and prone to oscillations if not properly matched over a large frequency range, which may destroy them instantaneously. They are also very unforgiving about driving power spikes.

This means that some form of input attenuator (preferably variable) and limiter will have to be included into the system.

Also, the question of frequency response arises.

From what can be seen in the SD3933 data sheet, one transistor barely reaches 350 W before saturation in the narrow-band test circuit at 30 MHz. Broad-band output matching networks have losses, and it may not be possible to reach the 350 W figure per transistor over the whole HF range. RF feedback may make this easier,and also improve the IMD performance.

Another aspect is unconditional stability. An amplifier that is to be used with "amateur-type" antennas must not oscillate even if the load should be badly mismatched, and the drive power must be reduced to safe levels if the SWR starts to exceed 2:1 or so.

Finally, the cooling requirements will be substantial.

At a key-down power output of 700W, about 1 kW will need to be dissipated in the amplifier box. This includes losses in the matching networks and output filters, drive power dissipated in the input attenuator and the losses in the power supplies.

The bottom line is that it is possible to build such an amplifier (and it has already been done; the ALS-600 does this with 50V MOSFETS), but the cost of the protection circuits may make the product difficult to sell to the amateur market.

The professionals, on the other hand, have had no problems with such a design. A JRC 10 kW HF transmitter using 100V MOSFETS has been on the market for nearly 20 years, but there you do not have the problem with 100 or 200 W transceivers as drive sources.

73/

Karl-Arne
SM0AOM
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K6AER on June 6, 2008 Mail this to a friend!
Although MOSFET amplifier are intriguing there are several problems in dealing with high power MOSFET’s. Many good points have been mentioned above.

The devices are very expensive and will not take any VSWR high voltage. Many THP amplifiers have been returned when subjected to high duty cycle operation. I would absolutely not use a solid state amplifier with an external antenna tuner. The amplifier must see a stable 50 ohm load. One of the cost associated with high power solid state amplifiers is they have to be very conservative in the ratings in order to have enough head room for device safety and low IMD specifications.

The ARF-1500 high voltage MOSFET you quoted is temperamental when run at close their maximum ratings. THP limits their output to 900 watts on a transistor rated for 1500 watts at 125 volts Vcc for just this reason.

Switching power supplies are very expensive for high power solid state amplifiers. Typical amplifier efficiency is about 50-55%. For a 1500 watt amplifier you will need about 2900 watts of DC conversion and that leaves no extra head room on the power supply. At $.60 per watt for high power switch mode supplies you have a power supply cost of over $1700 for the power supply alone.

You can go the iron route with the power supply but now you have a power supply that weighs more than a transformer on a tube amp with twice the output rating. High current capacitors are also more expensive than their High Voltage counter parts used in tube amplifiers.

The RF filtering needed for a solid state high power supply is problematic. The second harmonic can be as much as 150 watts of power at 1500 watts out. Remember the solid state amplifier is broad banded on the out put matching network unlike a tube amplifier. Conventional low pass filtering presents a problem. The filters will heat up and the reflected power causes a lot of mixing in the signal reflected back to the output devices. You need a diplex filter with the unwanted harmonic energy being feed into a load in order to obtain a clean output. This greatly increases the cost for needed filter requirements.

The IMD problem is the biggest single hurtle to overcome with solid state amplifiers. In order to have decent IMD of 33 dB or more, the amplifier devices have to be run very conservatively. If you want to run 1500 watts out you need to build an amplifier for 3000 watts. With tubes this is not a problem for tube dissipation will handle the low duty cycle of power excursions of 3 db or more. Exceed a solid state device buy a few tenths of a dB and the device will POP. No protection circuitry is as fast as the tiny bond wires in a RF transistor.

As for heat and efficiency, today’s ceramic tubes put out very little heat for the filaments only. Electronic biasing shuts the tube off between words and at 1500 watts out ceramic amplifiers produce little heat in the SSB mode. This was not the case with my old glass bottle amps but even then they were nice in the winter time.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by WA7NCL on June 6, 2008 Mail this to a friend!
The author is on to something. But I think you would want to use some sort of high efficiency switching technique to increase the efficiency to make the cooling problem managable. Also I would not make the power supply directly coupled off line buck. For safety reasons an offline transformer would be preferable. It could run at high frequency. Also some sort of power factor correction would be required in the power supply off line section.

Unfortunately, the market for this device would not support the developement costs.

Keep on dreaming, when I started in the hobby 40 years ago, everbody knew that "transistors were no good for RF work" and tubes were easier to work with.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by N4OI on June 6, 2008 Mail this to a friend!
This appears to be the spec. for the new Elecraft KPA-700.... :>)
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K1CJS on June 6, 2008 Mail this to a friend!
To go off on a tangent for a moment, yes, you should finish the article before even thinking about submission. If an article looks complete, even though the author claims it isn't it'll be put up on this site--the claim is insufficient time to read through the article, and it does look like that is true. If you request help, however, maybe you will get it.

Also, the links being printed in yellow is not good--it is hard to read, and I, for one, won't click on an unknown/unseen link

The article does have enough holes to drive a truck through, and some downright dangerous ideas. One thing to remember is that although amps are nice to have, quite a few that have them use them once or twice a year. The amount sold would never support--never mind repay--the developmental costs to the various companies, except probably MFJ.

I can't see your wish coming true--at least not now.
 
10-Pound 700-Watt Automatic Amplifer  
by WB8YYY on June 6, 2008 Mail this to a friend!
While not suggesting we give up our QRO freedom, I think the notion of solely focusing on boosting our power output will more quickly lead the hobby to extinction! I wonder if the UK has it 'right' with its traditional 400 watt limit.

We will come across as dinosaurs if we insist on needing ~ 1 kW to communicate a few hundred miles with a 10 or 50 lb amplifier stretching the limits of our AC wall outlets. Our paradigm should be comparing to the little cell phone. We do have evidence of doing nifty things with new modulation schemes (PSK31 and the like). Our modern rigs are generally nice advances, and i think the future of the hobby is doing more with less power, lighter antennas, and better coexistence with our 'surroundings.' OK a nice moderate amplifier might also fit the picture if we don't take it to extremes -- and know where its off switch is when the barefoot rig will do the job. Finese may not break thru the huge pileups of the 'elephants' within the hobby, but its key to our overall health.

73, curt
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K2DC on June 6, 2008 Mail this to a friend!
Just a couple of practical issues. You mentioned that the efficiency is up to 70% in Class B and the transistor seems very linear. While the data sheet indicates that the gain curve is very linear, Class B is not a linear mode. Only Class A is strictly linear, and AB, AB1 and AB2 modes are considered close enough to linear for SSB. I agree with an earlier post that the realized efficiency for Class A or one of the AB modes would be closer to 50%. I am also not an amplifier designer and I haven't analyzed the test circuit, but my guess is it's Class C.

Another practical issue is the gain. With a nominal gain of 29 dB a pair of those transistors would need only 250mW input to drive them to near saturation. That's a tough limitation on the control functions of most modern HF rigs withough heavily padding the input and dumping a lot of input power into heat.

Not a bad idea, but practically I don't think it's the right device.

73,

Don, K2DC
 
10-Pound 700-Watt Automatic Amplifer  
by KI4SBJ on June 6, 2008 Mail this to a friend!
There are people working on this at this moment.

http://hpsdr.org/wiki/index.php?title=THOR

What you need is class D, E, or F switched amplifier using using Envelope Elimination and Restoration (ERR) techniques.

John KI4SBJ
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by W3JJH on June 6, 2008 Mail this to a friend!
The power supply design you suggest would be a license for some product liability lawyer to sue the amplifier company out of business. Primary to secondary isolation is an absolute necessity for safe operation from AC mains, and that requires an input transformer. It would be safer to build a power factor correction front end that generates a 400 V dc bus on the primary side and to use a transformer-coupled switching convertor (bridge or forward convertor) to generate the secondary power.

It would be quite unusual to use a toroidal core for the power transformer. An E- or EI-core would be more typical at a power level approaching 1 kW.

Finally, 10 pounds of aluminum probably will not be sufficient for the heat sinks, let alone the rest of the amp's structure. You'd be lucky to achieve 40 % real efficiency in the amp. 700 W of PEP is a real 350 W of average power. The PA will need to dissipate around 525 W. The total output required from the power supply will be around 875 W. A good switcher will give 85 % efficiency, so that's another 155 W of heat. The power factor corrector/preregulator on the primary side will probably run at 95 % efficiency, so that's another 55 W--for a total of 735 W of heat at full output. 73.5 W/lb will require a very good heat sink design even allowing for forced-air cooling.
 
10-Pound 700-Watt Automatic Amplifer  
by KE4ZHN on June 6, 2008 Mail this to a friend!
MOSFET amps are very nice when properly designed. However, right now they are still a bit too pricey for what you get. This is most likely due to low sales volume. Tubes have gotten outrageous so its only a matter of time before many amateurs dump their tube amps and go to MOSFETS. My next amp will be a MOSFET for the simple reason I cant see paying more money for tubes than the whole amplifier is worth as a complete unit. Yes, theres nothing like seeing the glow of large bottles in your amplifier while its making watts, but Im afraid their days are numbered. High voltage MOSFETS have their quirks too but the advantages seem to outweigh the disadvantages of using them. It will be nice to have a solid state PA that follows the rig like a puppy dog without tuning and headaches while making a kw. Not to mention that the MOSFETS just dont wear out like a tube eventually does. No matter how much you baby a tube, it WILL eventually fail.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by SM0AOM on June 6, 2008 Mail this to a friend!
If you want to see how much circuitry and cooling that would be necessary, I suggest a look at the German Hilberling PT-8000B transceiver,

http://hilberling.com/produkte/produkte_pt8_t9.htm

that uses these MOSFETS in its PA stage. Due to the use of generous application of RF feedback and a 10 W Class A driver it is one of the cleanest HF transceivers around, with a - 40 dB IM3 rating. In order to achieve this, "harmonic dump" filters have been used at the output of the PA, according to professional practices. This prevents the generation of IM products by reflecting the harmonic power back into the transistors.

The test circuit shown in the SD3933 data sheet has adjustable bias between Class B and Class AB.
Class A operation may not be possible due to dissipation concerns.

Use of the ALC or "power control" mechanism in "run of the mill" transceivers to control drive for such an amplifier is an invitation to disaster, as "power spikes" or "overshoots" are very common.
 
10-Pound 700-White Elephant  
by AI2IA on June 6, 2008 Mail this to a friend!
Forget the amplifier. Concentrate on a good antenna or antennas. You will be much better off, money-wise, skill-wise, transceiver operation-wise.

Also, when you hear a weak signal, you have a fancy transceiver with all sorts of bells and whistles. Learn how to pull in those weak stations surrounded with noise.

What good are all the frills and power without good operating skills.

Put those buttons and knobs to work! Save money and electricity!
 
10-Pound 700-Watt Automatic Amplifer  
by N1YRK on June 6, 2008 Mail this to a friend!
I think that amplifiers should be like the 'boat anchors' of the past. They should be forged, and then machined, out of the highest quality metal to act as a 'heat sink', but more importantly, so that the bearings and vernier drives can have that silken feel of quality machinery. There should be lots of knobs, switches, meters, indicators, and accessory jacks. I mean, if you're going for QRO why should it like a dinky QRP rig?






bronx cheer to anyone that doesn't understand my humor.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K6AER on June 6, 2008 Mail this to a friend!
Having a great beam up high, located in a quiet location and all the operator skills in the world will not help the guy on the other end if he has a high noise level with his G5RV 20 feet in the air due to his hiding the antenna from the CC&R’ Nazis.

He needs more signal to overcome his high noise level and it is up to you to legally bring up your power. I live in a very quiet location and I have found most 100 watt stations will not hear my 100 watts unless their signal is S7 on my meter. Most hams live in a very noisy environment. Run an amplifier and all of a sudden there are all kinds of low power stations coming back to your CQ.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by KB9CRY on June 6, 2008 Mail this to a friend!
Forget the amplifier. Concentrate on a good antenna or antennas. You will be much better off, money-wise, skill-wise, transceiver operation-wise. Learn how to pull in those weak stations surrounded with noise. What good are all the frills and power without good operating skills.


Ah, YES. But imagine what can be had with super antennas, a super rig, a super amp, and a super op???!!!

THAT is the true goal.
 
Learn to walk before you run.  
by AI2IA on June 6, 2008 Mail this to a friend!
WITH EXCEPTIONS, careful observation of ham buddies at their hobby reveals that they pass by weaker stations, especially when the noise or fading is strong in the environment. They go for the loud, easy contact stations. Not surprising because most shout their calls into their mikes with no regard for courtesy. Careful observation of ham buddies at their hobby reveals their lack of receiver operation skills and lack of interest in receiver characteristics in general. It's not exciting to them like high power linear amplifiers. Most are in a hurry to acquire short cuts and bypasses to crashing through pile-ups and being admired on the air as big, busy, and powerful.

Listen to what your buddies talk about during their ragchews. It's not receivers! Wow! Big brand name antennas, gee I wish I had a tower! Comparing one linear amp to another, and so it goes. Volume, quantity, power, brand names, exotic locations - these are the conversation topics. For most it is more important, if they only could, to log in six hundred stations, than to pull in that weak one, but they can't do that, and they won't try it, either, in spite of the big fancy rig with all those digital features. Having is not being. Having all those goodies is not being able to use them well. Ever hear an on-the-air ham use the word "practice"? Log that one in as a rare contact. Now at the beginning I did say that there are exceptions for those who use linear amplifiers wisely.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K1CJS on June 6, 2008 Mail this to a friend!
".......But imagine what can be had with super antennas, a super rig, a super amp, and a super op???!!! THAT is the true goal."

Another words, he who has the most toys wins? No, it doesn't work that way. The true goal is doing the most with the least. Tha ham who does that is the real winner. Good antennas do help and should be the first concern before power amplifiers, but the sense of accomplishment you get while QRP with a dipole out in the field can't be beat!
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by NB3O on June 6, 2008 Mail this to a friend!
"QRP with a dipole"
Don't know if I would have enough patience to pull somebody out buried under the summertime static unless it was a "new one". A few extra dB of link margin does wonders for a good QSO this time of year.
 
RE: 10-Pound 700-White Elephant  
by AA8X on June 6, 2008 Mail this to a friend!
Absolutely, going with a great antenna system is the best answer, but when you have CC&R everywhere, running all the power you can into a little restricted antenna is the only answer.
 
10-Pound 700-Watt Automatic Amplifer  
by KI6JUU on June 6, 2008 Mail this to a friend!
Receipe for Tiger Tail Soup
First, take the tail of one tiger.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by N3JBH on June 7, 2008 Mail this to a friend!
I would think if such an amplifier was economically feasible W8JI would have designed it and MFJ would be selling it. Being I do not see MFJ selling it I don’t think it is as easy or cheap to make. There for I doubt it is feasible.
 
Nobody posts about this part:  
by AI2IA on June 7, 2008 Mail this to a friend!
The licensee must perform the routine RF environmental evaluation, if their HF power exceeds these limits:
160m 500W, 80m 500W, 75m 500W, 40m 500W, 30m 425W, 20m 225W, 17m 125W, 15m 100W, 12m 75W, 10m 50W.
Not to mention the requirements for the other bands.

If you feel that you must have it, well then go do it, and do it safely and according to Part 97. It has many advantages as far as DX and "getting through" goes. When used, it can make communication easier, if that is important to you.

On the other hand, consider the savings, the reduction in maintenance and repair, no environmental evaluation needed, and the satisfaction and fun of growing your skills in using your rig without the amplifier. If you can afford one, it's probably good to have one available in case you want or need to use it. On the other hand, unnecessary complexity and cost are simply headaches. The choice is yours.
 
10-Pound 700-Watt Automatic Amplifer  
by N0AH on June 7, 2008 Mail this to a friend!
Who needs an amp-
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K6AER on June 7, 2008 Mail this to a friend!
“On the other hand, consider the savings, the reduction in maintenance and repair, no environmental evaluation needed, and the satisfaction and fun of growing your skills in using your rig without the amplifier. If you can afford one, it's probably good to have one available in case you want or need to use it. On the other hand, unnecessary complexity and cost are simply headaches. The choice is yours.”

I can see this post is braking down into a, “I can’t afford an amplifier so I don’t want any else to have an amplifier”, troll. It almost becomes a religion by the QRP guys when they make a contact on low power. Never mind the guy on the other end has to suffer through QRM, QRN and is exhausted by the tine he gets the contact information.

Amplifiers are not that expensive. Good antennas up high are expensive. I disagree on the complexity issue. A well designed station properly executed is a piece of cake to operate. The only skill needed to wade through a pileup for a DX station contact is retirement. I have better things to do than spend three hours for one contact. Flip on the amp, bag the contact and do something else…like look for another DX contact.

Environmental evaluation is needed??? The RF absorption by the human body at HF frequencies in extremely low because your body is most resonate from 50-300 MHZ. Now if your running 1500 watts into a ground mounted vertical five feet from your station you might have a problem but the contacts on the other end will tell you about the RF in your microphone audio. That will be your first clue about excessive RF in the shack.

It’s summer time and in the afternoon nobody can hear 100 watt stations due to lightning crashes every four seconds. I run an amplifier so the guy on the other end can enjoy the QSO.

The rational for DXing using only QRP kind of reminds me of NASCAR racing where the last place driver tells his crew about how much skill he had in finishing the race.
 
Examining the issue - thoroughly!  
by AI2IA on June 7, 2008 Mail this to a friend!
I posted on here for the purpose of pointing out good reasons why, if you choose not to use an amplifier, you have some real advantages.

I have an ammplier. I have a nice 220 volt hookup for the amplifier, and I can afford a dozen good amplifiers, if I wanted them. I choose to operate straight from the rig.

Now we have a post on here where the ham admits that he does not want to take the time to work a difficult station. Good! He admits it. To operators like him I say that you are short changing yourself and not acquiring the skills in using your rig that you might need in an emergency. You don't want to be a good operator. You want to be an easy operator. Okay! Some take that approach. Enjoy yourself. You prefer quantity and ease to skill. That's fine if that's what you want.

You can have both QRO capability and use, and the enthusiasm to pull in those weak stations, but it's all up to you. Ham radio is what you make it for yourself.
 
It's not just a good idea. It's the law.  
by AI2IA on June 7, 2008 Mail this to a friend!
"Environmental evaluation is needed??? The RF absorption by the human body at HF frequencies in extremely low because your body is most resonate from 50-300 MHZ. Now if your running 1500 watts into a ground mounted vertical five feet from your station you might have a problem but the contacts on the other end will tell you about the RF in your microphone audio. That will be your first clue about excessive RF in the shack."

Your may have your opinions about environmental safety, but Section 1.1307(b) is not an opinion. It is the law. Yes, if the power you use exceeds the limits given, then environmental evaluation is needed.
Again, linear amplifiers have a long history with amateur radio and this is as it should be. To use or not to use in conformance with the rules and regulations, is purely your free choice. I don't criticise those who use them, but I do believe that those who don't are also good hams.
 
Everybody with good ears and skill.  
by AI2IA on June 7, 2008 Mail this to a friend!
"It’s summer time and in the afternoon nobody can hear 100 watt stations due to lightning crashes every four seconds. I run an amplifier so the guy on the other end can enjoy the QSO."

Funny, but I have a practice of going on the air every day. I have a little goal for myself to help keep the bands alive. It is this: I will achieve at least one QSO a day. Funny, but I always meet my goal. It may not be 600 contest contacts. It may be just two or three, or more, but I always meet my goal with 100 Watts. Somebody hears me. Somebody hears me quite well. Oh, lightning crashes you say? Uh huh! Yeah! Well not all bands have the same degree of lightning noise, but this excuse is hardly relevant. As for QRP, well you can do QRP and you can do QRO. Why not do both. Learn the skills to do both well. Be a well rounded operator. Again, be it a little world or be it a big one, ham radio is what you make it for yourself.
 
Amplifier cost  
by WB2WIK on June 7, 2008 Mail this to a friend!
Amplifiers are already a very low cost investment in amateur radio enjoyment, whether they're homebrewed or commercially built.

I built my first amplifier, a pair of 4CX250s for six meters, at the ripe old age of 14 and it cost about $500 or so for all the parts. I had a part-time after-school job, a paper route, and "gift" money from relatives on birthdays to fund that effort.

It was a great learning experience, and of course I almost killed myself in the process. Even 2200Vdc can be lethal, probably. But I wouldn't trade that experience for anything.

Since then I've built fourteen amplifiers and also bought several. I never considered any of them -- not even the brand-new Alpha 78 I bought in 1980 -- to be "expensive."

They're actually a really small investment in a really big station improvement, once you have all the antennas you can possibly have, up as high as you can possibly get them.

I would not be inclined to try to "skimp" on amplifier design or construction. High powered MOSFETs are not cheap, and the peripheral circuitry supporting their operation shouldn't be, either.

I still use tubes on all bands, 1.8 through 1296 MHz, for my amps. But one of these days that will change, or I'll be buried with the tubes. Not sure which will come first!

Thankfully some tubes have extremely long shelf life. On 70cm and 23cm I'm still using 2C39's that were manufactured in the early 1960s and they work fine.

WB2WIK/6
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K1CJS on June 7, 2008 Mail this to a friend!
".....I can see this post is braking down into a, “I can’t afford an amplifier so I don’t want any else to have an amplifier”, troll......"

Wait a minute, who is trolling here? I see a good healthy discussion, no name calling and no mud slinging. Points are being made about both methods, and for once, everybody is being civil about it.

For cripe sake, there isn't a troll behind every closely held opinion. I see a different kind of troll in this quoted statement.
 
10-Pound 700-Watt Automatic Amplifer  
by WA9WVX on June 7, 2008 Mail this to a friend!
So you want a Solid State H.F. RF Amplifier that will be lighter than 10 lbs ... dream on. All you need to do is search the internet for Solid State RF Amplifiers and you'll find several Defense contractors building H.F. amplifiers for the International Military & Commercial Markets and they're EXPENSIVE!

As most have stated the short comings of the solid state RF amplifiers, which I agree. Transistors are very unforgiving compared to vacuum tubes. They're similar to a 3-legged (expensive) fuse when they're not provided with the correct electrical parameters.

I'm providing a web link for Rockwell-Collins:

PA-2220A 1 KW 1.6 – 29.9999 MHz RF Amplifier & Power Supply:

http://www.rockwellcollins.com/ecat/gs/PA-2220A.html?smenu=101

And their recommended CU-2041 ! KW Antenna Coupler:

http://www.rockwellcollins.com/ecat/gs/CU-2041.html?smenu=101

Take note regarding the Weight of each piece of required equipment ... it's way more than 10 pounds even being solid state!

You may want to say I'm comparing apples & oranges but the Rockwell-Collins engineering team are using four (4) 300 Watt FETs in parallel to insure the RF amplifier will produce the 1 KW Output. You might consider this engineering logic as an overkill but many hams don't think of safety margins when dealing with their equipment. Maximum Output is NOT always better!

The reason I included their 1 KW Antenna Coupler is for the fact that the RF amplifier is designed for a 1.3:1 or LESS VSWR otherwise it will automatically cut back the Power Output up to a 3:1 when it shuts down the solid state amplifier. Commercial Solid-State RF Amplifiers are engineered with this in mind even in the Land Mobile Radio, Radio Paging and Cellular Radio Markets. All of these manufactures can't be wrong with their solid state amplifier engineering designs.

One should consider that a 100 Watt transmitter feeding a 600~700 Watt Linear Amplifier will only increase the receiving signal 1 "S" Unit or 6 dB and 1200 Watts will increase the receiving signal 2 "S" Units or 12 dB. I'm not sure why the average ham thinks a RF amplifier is the only answer to a big signal. If you spent big dollars on a transceiver,"Then why don't you spent an equal amount of money and effort on your antenna system?" You'll be amazed how well your equipment will perform.

Dan
WA9WVX



 
RE: 10-Pound 700-Watt Automatic Amplifer  
by WA2JJH on June 7, 2008 Mail this to a friend!
What about cooling? Yup. Those SS amps that claim 500W+ and are cheap have a few things in common.

1)No low pass filters, band filters, or any TX filter at all.
2)To be used with a DUMMY LOAD ONLY.
3)HV RF MOSFETS as others pointed out, really do need many monitoring
parameters........otherwise........POOOSSHHH!!!!

I did get a 48V commercial supply dirt cheap. It has over 10 terminals to add your own thermisters, and other voltage and currant loop monitors to turn off the supply quick!!!! A gate bias supply is a 2 hour project.

My latest NITWIT DESIGN........For 12V

I have about 8 or 9 125W final amps. They all came out of decomissioned HF maritime SSB rigs. They use old fashioned Bipolar RF power transistors. It is a 12V design.

If, I feel like it...........I MAYBE COULD use a 6 port power combiner.
Perhaps I can phase them all up. I could then build lowpass filters for a few bands I use.

When all is said and done.......I would rather make my HL-2200 into a single 3-500ZG HF amp. I can only run 110VAC in my shack.
All the Heathkit twin 3-500z amps have wimpy power supplies.
A single 3-500ZD amp will output 800W SSB. I will get the missing 2.5db by using a currant Balun and adding more radials. 1500W is overkill for my QTH.

Cost: New graphite 3-500.......$200.
I added the Harbock improved power supply/bias/meter board for under $75(kit form)
Shoot, I can get a new capacitor bank from HARBACH too.

HV RF MOSFETS are best for the commercial TV industry. The local I used to work for(WPIX-NY) loves their 25KW ERP TX- MOSFET HPA.

They have 25 HV RF MOSFET "HOT SWAP CUBES". If a MOSFET CUBE blows out, the viewing public never will see any change!!!!!
Many TV TX's are run this way. Some still use a siamese HPA with tubes that are as tall as us!

I love new tech as much as anybody. I did build a quad MRF-150 AMP. The all copper heatspreader weighs 20lbs!!!
I guess one could use TEC's to extract the waste heat.
I have seen ATU's claim to handle 500W+. Harris sells a 1KW ATU.
Mil spec of course. Harris does not like to quote prices. So, I guess it is THAT expensive!!!!

 
RE: 10-Pound 700-Watt Automatic Amplifer  
by KC5CQD on June 7, 2008 Mail this to a friend!
"The rational for DXing using only QRP kind of reminds me of NASCAR racing where the last place driver tells his crew about how much skill he had in finishing the race."



No. The rationale for DXing using only QRP is simply that some people really get turned on by the idea that they chatted with someone three thousand miles away, running only five watts. Real simple.

And as for all of the B.S. about "how hard the receiving station has to work in order to copy those QRP stations"........I've held numerous QSO's with QRP stations and didn't have a lick of trouble in copying them. And.....I've had many QSO's with guys running 1500 watts wherein I had to cut it short because I just couldn't pull them out.

Conditions, conditions, conditions.

When the atmosphere propagates that signal smack-dab onto your QTH, it doesn't matter the power. And when the atmosphere bounces that 1500 watt signal off the ground 300 miles from your QTH.....it may as well be a QRP station. Because you ain't gonna hear it!!!

Me? QRO or QRP.....I just love radio. I have an amp but quite often it sits idle with the rig pulled back to 5 watts. And the funny thing is, is that I make just as many contacts and ALWAYS get a 559, 579 or 599 RST. Well, until they hear that I'm QRP, that is. Then suddenly it drops to a 349. LOL!!!!!!
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by KC5CQD on June 7, 2008 Mail this to a friend!
Of course, as an addendum......

I do use an IC PRO III as my main rig and its receiver is hot enough to hear a gnat fart in Moscow. So QRP stations usually aren't any effort to pull out of the noise.

I actually got a chance to compare it next to an SG2020 at the same QTH using the same antenna. The PRO heard signals at S5 that the SG couldn't hear at all.

So maybe the lower-end rigs do have trouble with QRP stations. My PRO doesn't.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by WA2JJH on June 8, 2008 Mail this to a friend!
Sure QCD, QRP is great! Over my past 30 years as a ham, I have had 10 different QTH's.

First one was 230 feet above sea level. My uncle owned the roof rights.
I had a great location. Worked Japan on CW with 4 W out of a Argonaut 509.

In the late 1970's, 10 and 15M were hot as 20M.

My newest QTH is not to great for DX. I hear them on SSB. They can just barely hear me with 100W.

QRO up to 500W or so, I get my share. Comparing CW and SSB?????!!!! CW a mere 2-3db s/n is good enough.
Try working 160M QRP. The sun spot cycle is a huge factor as well.
Talk is that in about 2 years, it will be like 1977-1979 agn.

Back in 1978, we were all converting CB's over to 10M.
10M was a hot CW band during that cycle.

When 40M is filled with SW broadcasters at say 0200H UTC, you are just pulling in QRP DX? NOT BLOODY LIKELY!!!! :)

There is a time for anything. True, a few hams equate 1500W with serum testosterone level.

Seems like most of the SSB DX I work, use a 200W radio,(the 200W FT-1000D) with a beam up more than 1/2 the wavelength of the band I am working them on.
They all got their 20M beams 40-60 feet above ground.
Their ERP is far better than the duffis running 1500W into a multiband vertical with few or no radials. They do not know the DX station is doing all the ""Heavy lifting""

The perfect radio for me would be a firmware enhanced TS-950SDX with a single 3-500ZG final. For CW, my K2(15W) is all I need.
Those ANTI-CW FOLK miss out on the best DX. However, live and let live.



 
10-Pound 700-Watt Automatic Amplifer  
by N9NWO on June 8, 2008 Mail this to a friend!
Yes, it would be nice. We do have 500W (ie SGC) amps that in this category.

However, do I want all hams to have high power? Would it not be better to limit Techs and Generals to 250W and only allow Extras to have full legal power? That would give Extra Class hams four times the power of the other classes.

In many ways it would be better to limit power than limit on what frequencies we transmit on. If we could transmit on all frequencies then there could be far more interaction. The lower classes may not be ready for full power, not that we do not have our share of abusive hams in the Extra ranks.

 
So far - a good discussion.  
by AI2IA on June 8, 2008 Mail this to a friend!
I am very happy to see a good, courteous discussion so far about the advantages and disadvantages of linear amplifiers, and by way of that discussion the advantages of barefoot and QRP operation. This has been one of the more rare eHam.net threads where we all can get something positive out of it regardless of whether or not we choose to acquire and use linear amplifiers.

I will say this: The ARRL has a great book on building your own linear amplifier. It is a good way to learn about them, even if you don't build your own. It is also a great reference when you want to build your own and have the satisfaction of really knowing your amp inside out when you fire it up.
 
RE: So far - a good discussion.  
by N2UGB on June 8, 2008 Mail this to a friend!
I agree with N9NWO. There is something to be said about incentive licensing advantages being in the power allowed and not HF frequency allotment. I may be mistaken, but wasn't that pretty much the "10-watter" license class in a few countries?

Good civil discussion all around.
 
Power and Radio Laws are twins.  
by AI2IA on June 8, 2008 Mail this to a friend!
In regard to power and incentive licensing, I would say that power privileges and knowledge of radio laws should go hand in hand.

The first concern of the FCC would seem to be that radio operators do not interfere with each other and with critical radio transmissions such as emergency traffic, police, fire, rescue, military, and other services. The more power used, the more likely an operator unfamiliar with the radio laws would cause serious interference to critical services.

In fact, I would go so far as to say that the single most important knowledge license holders should know is a good practical knowledge of the rules and regulations. So to me the most important part of license testing are the questions on the radio laws. The rest will follow. Extras are expected to know the laws well and therefore are most accountable when they operate anywhere in the bands. Generals also operate in most places and they need to know what they are doing, too! Techs and such are much more limited in the scope of their operating privileges, and yet they need to know what they can and cannot do as far as the laws go.
 
The old power rule  
by AI2IA on June 8, 2008 Mail this to a friend!
Back in the early Sixties when I learned radio electronics, they always taught that a reliable indication of the power handling capability of a component or a device was its physical size.

A physically larger resistor or transformer handles more power than smaller ones.

If you look inside an AM broadcast transmitter and see the size of the components, right away you feel a healthy respect for the power that would be in there if the transmitter were on the air. You look at large components and you expect to see a wooden pole with a heavy wire and clip at one end and a rounded shorting tip on the other to ground big capacitors when you power down the unit and open it up.

We can lighten things by reducing the heavy gauge copper wire, but it is likely that massive components will probably always be associated with massive power.

Look how tiny you can build a milliwatt device. Look how big a megawatt transmitter can be!
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K6LHA on June 8, 2008 Mail this to a friend!
N9NWO almost revived 'incentive licensing' on 8 Jun 08 with:

"However, do I want all hams to have high power? Would it not be better to limit Techs and Generals to 250W and only allow Extras to have full legal power? That would give Extra Class hams four times the power of the other classes."

Excuse me, but WHY?

"In many ways it would be better to limit power than limit on what frequencies we transmit on."

HOW can that be done - practically - without imposing a LARGE burden on the FCC's budget?

"The lower classes may not be ready for full power,..."

Oh, oh...here we go with Class Distinction and one needing 'radio experience in order to upgrade to higher power.'

55 years ago a 20-year-old unlicensed-in-radio soldier was assigned to an Army station which had 36 HF transmitters ranging from 1000 Watts to 15 KW (40 KW added after 2 years). That was me, hardly different than other newbies-to-HF-radio of about 50 that ran the station 24/7 with traffic all over the northern Pacific to a traffic rate almost a quarter million a MONTH. How much "lower" can one go than NO experience in HF communications?

No problem, we did it like personnel before us and those who came after did it up to 1963. The US Army didn't have any Fixed Station Communications school then so some of us only had theoretical basics of 'radio.' We learned what to do by on-the-job verbal training and hands-on demonstration. Everything survived. :-)

A 1000 Watt HF transmitter puts out more power than any 700 Watt amplifier. Considerably more in using the 15 KW HF transmitter as a comparison. :-) Absolutely-no-experience young men could do it effectively but now, 55 years later, an amateur has to 'upgrade' to use more power in a HOBBY?!?

Just by my experience and that of hundreds of other GIs in my position, the necessity to gain 'experience in radio' FIRST to handle greater output power is a fabrication with no basis.

This article concerns itself with technology and advancing the state of the art. It is NOT, and should NOT be about introduction of any class distinction in licensing. Those are two very different subjects.

73, Len AF6AY [Amateur Extra class US licensee]
 
Linear Ampliers and Qualifications to Use  
by AI2IA on June 8, 2008 Mail this to a friend!
"Oh, oh...here we go with Class Distinction and one needing 'radio experience in order to upgrade to higher power.'"

Consider that on the Amateur Bands just for quick example: Novices and Technician Plus licensees are limited to 200 Watts PEP output on 10 meters. Novices are limited to 25 Watts PEP output from 222 to 225 MHz. Novices are limited to 5 Watts PEP output from 1270 to 1295 MHz.

HAVING CLASSES OF LICENSES IS INTENDED TO CREATE CLASS DISTINCTION.

The FCC equates the privilege of increased power with the incentive to move to a higher class license. What do you suppose is their reason for that?

"This article concerns itself with technology and advancing the state of the art. It is NOT, and should NOT be about introduction of any class distinction in licensing. Those are two very different subjects."

This article is about linear amplifiers. An important feature of linear amplifiers is "who is qualified to use them." Never try to block legitimate inquiry. This is how we grow in knowledge.

Army experience is irrelevant to Amateur Radio licensing. I have had many years of Air Force radio experience. I held and continue to hold a GROL (commercial license). These are irrelevant as far as Amateur Radio Licensing is concerned. If I wish to operate on the Amateur Radio Bands, then I must prove by means of passing a test or tests that I know the Amateur Radio laws (Part 97) and amateur radio practices. This is as it should be. Education about anything, and wise management of anything are all about "distinctions." Distinctions are not the same as prejudices. They are all about knowledge of differences critical to the operation or management of important things. Having an Amateur Extra Class license, as I do, does not make me a superior person to holders of lower licenses or no license, or even CB operators. It is a license class distinction based upon demonstration of knowledge of a special kind, and that's all there is to it. I hope this clears the air on these amplifier related matters. Additional comments are welcome.
 
RE: The old power rule  
by K6LHA on June 8, 2008 Mail this to a friend!
AI2IA posted on June 8, 2008:

"Back in the early Sixties when I learned radio electronics, they always taught that a reliable indication of the power handling capability of a component or a device was its physical size."

Well, I dunno who your 'they' people were, but in the early 50s when I learned more about 'radio' and electronics, I think we could all see that for ourselves. :-)

But, the "early sixties" were also FORTY-plus years ago. Times have CHANGED.

"A physically larger resistor or transformer handles more power than smaller ones."

...duhhh... :-)

"If you look inside an AM broadcast transmitter and see the size of the components, right away you feel a healthy respect for the power that would be in there if the transmitter were on the air."

I didn't work in broadcasting until after three years of working on HF power transmitters in the Army and then nothing in civilian broadcasting exceeding 5 KW (WBEL, Beloit, WI), never did have to pull maintenance on any of those BC transmitters. However, I did regular maintenance on HF transmitters in the Army (from 1 to 15 KW) as well as regular operation of them and that is detailed in the photo essay at:

http://sujan.hallikainen.org/BroadcastHistory/uploads/My3Years.pdf

AI2IA: "You look at large components and you expect to see a wooden pole with a heavy wire and clip at one end and a rounded shorting tip on the other to ground big capacitors when you power down the unit and open it up."

The 'shorting poles' I remember at station ADA were for hanging on the antenna selector switch to reduce minor RF burns from 600 Ohm open-wire feeder lines. When in the center of a TRUE antenna farm of maybe four dozen antennas and the 30 or so other transmitters are outputing a total of maybe a quarter MegaWatt of HF RF, one could always expect that. :-) I remember the Tx power supplies always having bleeder resistors across them to do self-discharging.

Those old power transmitters we handled 40 to 50 years ago were designed at least a decade before. Over a half century ago, designers: 1. Used very conservative ratings to insure reliability and longevity; 2. Used known parts which tended to be oversize even before adding design fudge factors. The LITTLE 1 KW HF transmitters I got used to were actually designed in the 1930s...which is over SEVENTY years ago. 'Battleship construction' was common back then because there was no need to make things smaller. Neither did they need lead-jacketed insulated over-heavy-gauge wire but they had that. The oil-filled plate transformer was easily oversized, weighed about a ton, almost the size of the 15 KW power supply transformers. [comparing Press Wireless PW-15s to military BC-339s]

About a year ago I held a small supercapacitor in one hand. It was rated in FARADS, no prefix on the capacitance value. Those are all about 1/100th the size of similar-capacity rated electrolytics. Sure they are low voltage NOW. But, also now, voltage breakdowns can be rated a bit over 100 VDC for production units. The way-higher capacitance values are done by increasing the capacitor plate areas on the molecular scale. Breakdown voltage does NOT equate to stored electrical POWER.

AC power transformers rated for 60 Hz have to be BIG because the frequency is so low. If you've handled aircraft electronics power transformers for 400 Hz, you will easily see for yourself. POWER does not always equate to size. Switching power supplies can be quite small since they switch at frequencies near or at the AM BC band.

As to power resistors, I've worked with and designed in were 25 to 50 Watt units that were physically MUCH smaller than their old, old unchanged-design wirewound, vitreous enamel covered type. See the old Dale manufactured type for an example. The old types had NO appreciable product design improvement in the last 80 years.

I've worked with thyratrons of many sizes, from 7-pin miniature glass envelopes to things that required both hands to hold. But, SCRs and their semiconductor cousins can easily handle KiloWatts in a MUCH smaller package, ones that will safely conduct excess wasted heat. As to handling 60 Hz AC power, check out any OLD industrial machine area needing power control-conditioning, versus a newer (no more than 30 years old) installation using semiconductor units. Smaller by at least one half.

AI2IA: "We can lighten things by reducing the heavy gauge copper wire, but it is likely that massive components will probably always be associated with massive power."

Once superconducting wire becomes a reality for consumer equipment design, we could see a thousand-fold reduction in that size, too...except that consumer electronics is using less and less power to run their products, not likely to need it. Wiring code in a typical residence doesn't allow outlets serving more than about 3 KW. The copper wire gauges are conservative and haven't been changed for about 60 years. The system allows for relatively low-cost building. We could use better systems of electrical power distribution in a residence except those would add initial labor when first built. Home builders don't want to add costs; what, and take away their profit? :-)

My landscape contractor showed me a new Xenon flood lamp last month. He got it for night jobs (for other folks, assuring me I wouldn't be overcharged for my needs, heh heh). 1 KW power demand. Brighter than incandescents, smaller in size than incandescents. I've got an old 300 W maximum socket and reflector for photo work 60 years ago...it is twice as big as that Xenon flood. Military vehicle lights designed in the 1960s could already do the same illumination as arc lamps but at a lot less power demand. [source: Dusk 'field testing' in the Electro-Optical Systems (a Xerox division), Pasadena, CA, parking lot, seen by many late-working employees]

A big danger to 'advancing the state of the art' is to remain UNCHANGED with what one 'knows that which should be (of many years past).' That's a very comfortable, emotional position, but rather dumb considering what has already been done in all of electronics to utterly CHANGE size and power demands.

Let's reflect on AM BC transmitters, compare new designs versus the old 'tried and true' methods used with vacuum tubes. Now we can build them MODULAR. Use several modules and combine them with RF transformers. We can include 'hot swap' capability to change one module WITHOUT turning off the whole transmitter. None of the modules need be optimized at one fixed frequency but can be designed to work over the whole 3:1 frequency range of the AM BC band. The FCC mandates ONE carrier frequency and a service area for that frequency, but that is a regulatory issue having NO relation to the electronics within the transmitter box. We can build the whole transmitter box smaller than a tube equivalent and NOT demand any more cooling or special environmental conditions than any tube type Tx. The only thing not changed is a directional antenna that needs a (passive) phasing unit to feed those. Their antenna sizes are a function of wavelength, not power.

I'm still waiting for SteppIR to ship my 'SmallIR' vertical order (late June). It is for 20m to 6m operation. When installed it will remain the same vertical size on the outside, but the ANTENNA ELEMENT LENGTH will change depending on operating frequency! One of the BIG changes in passive antenna designs in the entire 112-year span of all 'radio!' The visible vertical pole is a fiberglass tube that remains fixed. No funny-looking stubs sticking out at weird places, no need for a relatively huge log-periodic-like broadband antenna. Unobtrusive to neighbors. It is said to withstand 100 MPH winds...neat but we've never had more than 50 MPH gusts at this location in the last 43 years. Sure, it costs more, but then just about everything truly revolutionary in any technology does. The IDEA of it really DEFIES the old, comfortable 'tried and true known things' by a whole plateau jump in thinking. It is ELEGANT in its simplicity and unobtrusiveness.

AI2IA: "Look how tiny you can build a milliwatt device. Look how big a megawatt transmitter can be!"

Our Chevy's 2005 model Malibu has a tiny fob transmitter that is expected to last on the same battery for about 6 years or so. It also includes a specific encrypted code to prevent another auto-entry device from triggering the door...or horn...or remote start feature. It takes up less space than an old dollar coin.

I've held a search radar 2 MW magnetron and front end waveguide assembly in both hands many years ago for a prototype avionics project. I could also pick up the power supply and modulator assembly in both hands. The argument that "that's the PEAK power!" will immediately start. The counter will be that the AVERAGE power demand was about 800 W (and a smidgen more). That modulator-power unit was of less size than a Tokyo Power external RF amplifier not being advertised in amateur radio markets. Our Amana over-the-counter Radarange microwave oven is good for a KiloWatt of microwave generation, ONLY using what electrical power is needed to heat food; oven cooking chamber (a cavity) and magnetron characteristics take care of that. See 'Reike diagrams' and why they are needed. Nobody needs a 'license' to operate a microwave oven. Either one of our kitchen remodelers could lift the oven by themselves. A whole KiloWatt in a box, still operating after 9 years. It isn't for communications. It is for cooking. But it damn well operates on RADIO Frequencies.

Back in 1976 I built my first 'personal computer' from a Southwest Technical Products kit set. Included a 'dumb' terminal that would work with any monochrome TV monitor. I was an early buyer of the first true handheld scientific calculator, the HP-35, doing that 5 years before. In the year 2000 I bought an HP-32S II PROGRAMMABLE scientific calculator at Fry's Electronics, off-the-shelf for about $6o. It is still running on the same set of batteries that came with it! It's grand-daddy, the '35, had to be recharged overnight after about 6 hours of continuous use, was never a programmable device.

Lithium-ion batteries (with improved electro-chemistry to reduce fire danger) can hold KiloWatts in less weight and size, beating the heck out of old 'tried and true' lead-acid batteries and every other type of rechargeable battery ever known.

My present-day PC has MORE mass storage, MUCH FASTER operation than any IBM 360 or RCA Spectra 70 mainframe of 1967, sits on a computer desktop instead of taking up a 2000 square-foot ROOM (the size of my house) required for those old mainframes.

That's just a FEW examples of changes that have happened while I was alive and observing things in electronics and 'radio.' I could cite more and be specific about 'size v. power' but I've already pissed off a bunch of olde-tymers...most of whom are younger than I. :-)

73, Len AF6AY
 
RE: Linear Ampliers and Qualifications to Use  
by K6LHA on June 8, 2008 Mail this to a friend!
AI2IA rebutted on 8 Jun 08:

[AF6AY] "Oh, oh...here we go with Class Distinction and one needing 'radio experience in order to upgrade to higher power.'"

"Consider that on the Amateur Bands just for quick example: Novices and Technician Plus licensees are limited to 200 Watts PEP output on 10 meters. Novices are limited to 25 Watts PEP output from 222 to 225 MHz. Novices are limited to 5 Watts PEP output from 1270 to 1295 MHz."

"HAVING CLASSES OF LICENSES IS INTENDED TO CREATE CLASS DISTINCTION."

Gee, I always thought it was for some other reason... <shrug>

AI2IA: "The FCC equates the privilege of increased power with the incentive to move to a higher class license. What do you suppose is their reason for that?"

I'd say it was from intense lobbying by the ARRL aways back in time. :-)

Tsk, by 1990 the ARRL couldn't block the creation of the NO-CODE Technician license class, could it? That went into effect in 1991. Lobbying from OTHER US citizen groups was responsible. Remember that the ARRL membership is LESS than a quarter of all licensed US
radio amateurs.

[AF6AY] "This article concerns itself with technology and advancing the state of the art. It is NOT, and should NOT be about introduction of any class distinction in licensing. Those are two very different subjects."

AI2IA: "This article is about linear amplifiers."

Okay, we agree on that...at least it started out that way. :-)

AI2IA: "An important feature of linear amplifiers is "who is qualified to use them."

Is it? In the beginning I thought it was about trying to DESIGN them...using new ideas, new concepts maybe, DIFFERENT ways to solve the same problem. SOMEONE ELSE started up with vague remarks about 'limiting powers of General and Technician classes." [N9NWO to be exact]

AI2IA: "Never try to block legitimate inquiry. This is how we grow in knowledge."

Oh, my, good old folk sayings and aphorisms again...<sigh>

Who is 'BLOCKING INQUIRY?' Not me, sport. I was commenting about an UN-NEEDED comment of license classes having authorization to use them. Such authorization has NOTHING to do with DESIGN of them. ANYONE could DESIGN them, no license required.

AI2IA: "Army experience is irrelevant to Amateur Radio licensing."

If you say so, then it must be so, yes? NO. Depends on WHAT that experience is. Download:

http://sujan.hallikainen.org/BroadcastHistory/uploads/My3Years.pdf

The entire Department of Defense is NOT regulated by the FCC in radio matters, yes. But the PHYSICS OF RADIO apply universally without regard to how humans have divvied up who regulates what.

If you tell me that a Collins KWM2 'works differently' than an AN/FRC-93 (the DoD ID of that same transceiver), then you are bending truth too far. Same radio, different nomenclature. Radio physics applies. Human laws only affect who uses one and where and
which frequency is dialed up by a user.

What I did for my main Army task was operate and maintain HF transmitters having fairly hefty RF output powers. The lowest power unit was 1000 Watts RF out. That's fairly close to the Legal Limit for US radio amateurs circa 1953 (exact amateur regulation of '53
irrelevant in this new millennium).

AI2IA: "I have had many years of Air Force radio experience."

Doing WHAT? The USAF has lots of Military Occupation Specialties (or do they call those jobs by other terms now?).

AI2IA: "I held and continue to hold a GROL (commercial license)."

I tested for, and was granted a First Class Radiotelephone (Commercial) license in March, 1956. Kept it renewed until the FCC changed regulations and it became a General Radiotelephone Operator License (GROL), kept that until the FCC made them Lifetime, no
renewals needed. It's not a biggie in self-praise, yes, but I took it at an FCC Field Office in Chicago (90 mile train trip for me) and passed it at one go. Considering I prepared for that in only two weeks time, I was pleased with the result. Note: The US Army
didn't teach me anything about FCC *civilian* radio regulations...had to learn those by myself.

AI2IA: "These are irrelevant as far as Amateur Radio Licensing is concerned."

Did I say anything about REGULATION RELEVANCE? I don't think so. I was commenting about HIGH POWER Transmitters in the HF part of the EM spectrum and talking of experience in using them and maintaining them, beginning in 1953. A few months over 55 years ago.

AI2IA: "If I wish to operate on the Amateur Radio Bands, then I must prove by means of passing a test or tests that I know the Amateur Radio laws (Part 97) and amateur radio practices."

I did that on 25 February 2007. Passed on the first go for that one, too. It was very close to the 51st anniversary of my passing my First 'Phone exam. :-)

AI2IA: "This is as it should be."

NO. It is about what the FCC has written in Part 97, Title 47 Code of Federal Regulations. Part 97 can be changed by the FCC on US citizen requests under procedures outlined in Law under Title 47. If the FCC says one must 'know certain things' then it is true. BUT, and a BIG conditional there: The FCC does NOT make up the questions or answers for amateur radio
tests; that is a task for the National Council of Volunteer Examiner Coordinators' Question Pool Committee. The FCC only passes judgement in the form of acceptance or rejection of the submitted Question Pool. Go to www.ncvec.org for more information.

AI2IA: "Education about anything, and wise management of anything are all about "distinctions." Distinctions are not the same as prejudices. They are all about knowledge of differences critical to the operation or management of important things. Having an Amateur Extra Class license, as I do, does not make me a superior person to holders of lower licenses or no license, or even CB operators."

Wow! Sounds super stupendous achievement the way that is written. [I too hold an Amateur Extra Class license] But I wasn't going into such grandiose elloquence about my remark to another concerning which amateur license class can run which power.

'Wise management?' :-)

AI2IA: "It is a license class distinction based upon demonstration of knowledge of a special kind, and that's all there is to it."

All three US amateur radio test elements sum up to only 120 questions...all multiple-choice. It is not all that 'special' insofar as either regulations or knowledge of radio theory. Heck, the paper license certificate I got in the mail later was quite plain, no fancy decorations around the edges...:-)

AI2IA: "I hope this clears the air on these amplif
ier related matters. Additional comments are welcome."

'Clears the air?!?" Hardly. Your 'rebuttal' went on and on about Regulatory Matters, strange personal concepts of what the hobby is, nothing at all about DESIGN of very light RF Power Amplifiers. Nothing. The lead article was all about design of such and what MIGHT be done using different methods or components.

Given my limited experience in design of RF power amplifiers, I'd say offhand that "10 pound weight" of one is a bit too presumptive at this point in time. Perhaps 25 Pounds would be more realistic...based on viewing a couple of copies of Helge Granberg's solid-
state designs from an old Motorola application note. Those were done about 30 years ago by some friends at work (all amateur radio licensees). Helge brought out some more in the next few years. One can buy the parts to make most of those designs from Communications
Concepts, Inc. One could modularize several using hybrid couplers (all passive); Eight 100 W modules could make a 700 Watt total linear amplifier, no more than 100 W RF lost in the passive hybrid coupler-splitter-combiners. A switching power supply could provide either 12 VDC or 28 VDC depending on the Granberg design. Switchers are far more efficient than many think, can even be REGULATED with simple, low-power circuitry. The 12 VDC supply input could use an auto battery backup for emergency use.

A modular system lets one build a PA of Power from smaller, identical models. Each module can be tested, checked before integrating it into the whole. Granberg's designs were all broadband and would fit existing transceiver 50 Ohm impedance antenna ports and not even tickle the transceiver's VSWR indicator insofar as a 'bad match' was concerned. Heck, a 100
W RF input (typical) might be too much! The modules could be re-arranged or changed. Lots to choose from. A conventional Bruene output line detector could check for VSWR, output of that could electronically shut down the PA if too much VSWR. I'd say it all could be in a 25-pound package even if AC line powered and DC supply included. Might not be cost-effective for a ham market but homebrewers could roll their own. Technology of all the few parts have been around for at least two decades, can be found on the Internet or in HF radio related texts and literature.

But, what the heck, I'm just a 'beginner' in US ham radio and know 'nothing' about 'what ham radio really is!' :-) I haven't 'filled out enough log books yet!' :-)

Then again, I might be just a hobbyist trying to have fun and NOT subscribing to some of others' fantasies over amateur radio? :-)

I'm sure lots of folks will TELL ME what I am! Many have already done so. :-)

73, Len AF6AY
 
RE: Linear Ampliers and Qualifications to Use  
by N9NWO on June 9, 2008 Mail this to a friend!
To AF6AY, AI2IA and the group:

I have been involved in Amateur Radio since 1959. I have also just returned from a 15 month combat mission (I am an NCO in the USAR) in Afghanistan.

Look, when I was first licensed one was limited, as a Novice, to 75W. The idea was that could do less "damage" while you were learning. It makes more sense to limit the classes based on power than with respect to frequency (as we do now). I would rather have all of the classes freely intermingling than the private clubs (band restrictions) that we have now. Tech and General are classes to learn operating skills and technical knowledge so that when one has full privileges one should act in a responsible manner.

With respect to the military, these days we are under so much micro management because commanders can go to jail for a screw up of a private. Our society does not hold the individual responsible but rather the supervisor. The Marines are trying to go back to the system where the squad leader is the primary decision maker on the battle field with everyone above him focused on making that squad leader the best leader he/she can be. But that is a hard path in this politically correct (neo-Victorian) world.

I agree that we are to experiment. Generally a newbie is too focused on learning skills. It takes a while to go through the learning curve in any hobby or vocation. For example, working QRP is a very good way to become a better operator. So is contesting. But even there, skills take time to develop. At the beginning one makes mistakes. And few of us old cranky types tend to be tolerant of the newbie's mistakes thus if a newbie did so at full power, oh my!

I have seen some solid state amps being developed over the last few years that are compact and lite weight. In many cases they mirror the developments (solid state) that we are seeing in broadcast transmitters. Now if we could just see a drop in cost!

Again, a very good discussion....
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by WA3SKN on June 9, 2008 Mail this to a friend!
Better, faster, cheaper... pick any two!
I didn't know we measured amplifiers by weight.
Really, if you think you have a design that makes sense, try building it!
There are transistor amplifiers out there, just not with the specs you envision. But you do need to plan on the heat generated. Remember, even the new radios require about 250 watts to supply 100 watts output.
If you don't use metal to dissipate the heat, where do you put the "dry ice"?

-Mike.
 
10-Pound 700-Watt Automatic Amplifer  
by CHARLESPG on June 9, 2008 Mail this to a friend!
I dont think you see any of these soon.
The companys make too much off the big units

Now a 300 watt travel HF amp weighing 8/10 pounds
at a reasonable price. I'd might buy one
 
On taking a larger view:  
by AI2IA on June 9, 2008 Mail this to a friend!
I see by the ongoing string that some hams have issues with the FCC rules and regulations, other issues with their radio expert image, and a great deal of difficulty accepting the class distinctions of amateur licenses based upon the incentive licensing system.

Ridicule is never an effective tool in disputation. I suggest that it be dropped. It makes the user look inadequate and even foolish. I have not addressed anyone by name or call sign here, out of courtesy.

Mature, qualifed hams can handle linear power amplifiers and even build them, regardless of their license class. Military or commercial experience has no direct bearing on one's amateur radio image, authority, status, or ability. License class is not a pecking order. I suggest that those who are overly sensitive to it forget about it.

A final comment on age and ham radio. Age does not equate with experience, skill, or anything else. It is simply what it is, age. Take each ham or any person as you find them. Everyone is different. The "when I was in the military" gets tiresome after a short while. All appeals to some illusion of qualification do so. Enjoy ham rado. Participate in emergency communications, if you are up to it. Be a VE, if you wish, be active, but above all, be considerate and learn to appreciate the rules and regulation as they apply equally to everyone.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K6LHA on June 9, 2008 Mail this to a friend!
WA3SKN posted on June 9, 2008:

"Better, faster, cheaper... pick any two!"

Go for all three... :-)

"I didn't know we measured amplifiers by weight."

We don't...but it makes a good comparison on the progression of the state of the art in radio-electronics. I could show you a picture of a Collins Radio 50 KW CW transmitter that was used as a 40 KW PEP linear amplifier by the US Army. I've QSY'd a couple of those a long time ago. I have NO info on its weight other than knowing a crane truck delivered it to mount on a very thick concrete base at the transmitter building. It wouldn't fit in my living room and I'm sure it would wreck the floor supports if it were tried. :-) It was WIDE as well as high and memory tells me it was about 5 standard rack widths in size plus about 7 feet high.

WA3SKN: "Really, if you think you have a design that makes sense, try building it!"

Absolutely! The information on solid-state linears has been out in public view for three decades. One of the best such sources was Helge Granberg's designs from the former Motorola semiconductor group. Motorola was obviously pushing their RF power transistors at the time but the appnotes are SO detailed that they read like construction articles. Communications Concepts, Inc. even has free downloads of some of those appnotes.

WA3KSN: "There are transistor amplifiers out there, just not with the specs you envision. But you do need to plan on the heat generated. Remember, even the new radios require about 250 watts to supply 100 watts output. If you don't use metal to dissipate the heat, where do you put the "dry ice"?"

HEAT is, and has been, dissipated into the air in active-device power amplifiers since the 1920s. Thanks to the tremendous market in PCs we have all sorts of air-moving devices NOW...big, little, in-between sizes...pick and choose what you need. Heck, one can get sealed 'heat pipes' at some distributors, tubing with sealed liquid that vaporizes under heat and carries it away from power semiconductors to a remote heat sink, all without extra power demand.

Peltiere coolers are unique semi-semiconductor junctions that can make one of two junctions COOL while making the other junction HOT. Not that good idea since it adds to the overall heat load...for small lightweight RF power amplifiers, that is. They are GREAT for small, carry-in-the-car soda coolers or coffee heaters.

Semiconductor devices are small and they have very specific JUNCTION temperatures which can't get too high. Big glass bottle tubes could take a lot of heat but they had lots of surface area to help dissipate that heat. By contrast a pair of 100 W RF transistors has a heating area comparitively miniscule. Such heat has to be SPREAD out. That spreading is done by heat sinks. Heat sinks of many kinds have been available on the electronics market for 40+ years. One has to think in terms of RELATIVE temperature gradients with heat sinks. Not a 'conventional' "radio part" subject to olde-tymers but 'mature, modern designers' in electronics can work with those, no sweat. :-)

What MARKETED products do is pare the designs almost to the bone in order to reach a selling price the manufacturers think will sell. Those are never the 'best' designs...but advertising will try very hard to make you believe it IS 'the best.' :-)

Hobbyists doing one- or two-of-a-kind, HAVE the ability to compete with designs that CAN be small and lightweight and still perform. In truth, most licensed radio amateurs would rather just play with their radios and tackle only simple 'weekender' projects that don't stress their minds. <shrug>

Dry ice is for soda pop products. IN them. :-)

73, Len AF6AY
 
RE: Linear Ampliers and Qualifications to Use  
by K6LHA on June 9, 2008 Mail this to a friend!
Posted By N9NWO on 9 Jun 08:

"To AF6AY, AI2IA and the group:

I have been involved in Amateur Radio since 1959. I have also just returned from a 15 month combat mission (I am an NCO in the USAR) in Afghanistan."

"Look, when I was first licensed one was limited, as a Novice, to 75W. The idea was that could do less "damage" while you were learning. It makes more sense to limit the classes based on power than with respect to frequency (as we do now). I would rather have all of the classes freely intermingling than the private clubs (band restrictions) that we have now. Tech and General are classes to learn operating skills and technical knowledge so that when one has full privileges one should act in a responsible manner."

Agreed in general...and a salute to you as one veteran to another! Go Army! :-)

The original concept of reduced privileges for 'lesser' license classes had some merit for those whose ONLY entrance into the world of radio was through amateur radio. Around 1950 or so, that was operative.

But, it was also very true that there was a built-in 'we are better' attitude by the 'upper classes' to promote that. It gave those 'uppers' a rationale for keeping that system. They deny it vociferously but long observation of watching human beans tells me it is true. :-)

Big problem that exists in reality: Times and States-of-the-Art have CHANGED just in a half century!

I've lived through it, worked in it, felt the CHANGE all around.

I'm not going to comment on military small-unit leadership. This isn't the place. Rather, I'll bring up a comparison of RADIOS used by US military small units on land.

Back in the mid-1950s the common back-pack (later changed to term 'manpack') radio was the three overlapping-band VHF FM voice transceiver in the AN/PRC-8 to -10 series. Half the weight of the WWII 'walkie-talkie' (SCR-300). 13 tubes, 12 of them being subminiature types, a tremendous 1/2 W RF output. :-) I carried one a few times during infantry
retraining exercises. It was all VFO tuning, channelizing by using a spotting heterodyne
from an internal crystal oscillator.

Jump ahead 40 years and land forces small units have the AN/PRC-119 SINCGARS manpacks, PA-boosted mobiles, or airborne. Over 300,000 have been produced and fielded. As a civilian I've tested a few in their early models (before the SIP versions that reduced their bulk to HALF). They can operate single-channel on VHF in the clear (digitized voice on FM but no
encryption) or do frequency-hopping (10 times/second) and encrypt their audio on-the-fly AND keep sync with a network of other SINGARS radios with the correct hopset. The front panel doesn't even look like a 'radio' to many. :-) Just an LCD touch-screen for most of the operations settings (and some built-in self-test functions). Looking at its insides and
comparing the -119 to a -9 is like comparing Bambi to an alien from outer space. They share only 'modularity' and olive green exterior paint.

Thinking as a GI that I once was, that SINCGARS is a boon and a half. On-the-fly encryption means the enemy won't know what our side is communicating. They can't possibly hear us, unlike in the Vietnam War with the earlier PRC-25/-77.

A point of this is that 'RADIOS' don't have to LOOK like they did back in the mid-1950s. They don't have to BE BUILT from the same things. They don't even HAVE TO USE vacuum tubes. WE don't have to set our standards the same way they were a half century ago. The rest of the international radio world has advanced in the state-of-the-radio-art...so why can't amateur radio keep up? It tries but only in what mostly-off-shore designers and manufacturers do...while the 'USA-made' folks are content to play catch-up in their
products later.

What I see is too many olde-tymers who are trying to enforce Their concepts of What Amateur Radio 'should' be. It isn't coincidental that their concepts are what was drilled into them back when they were young and just beginning, even older old-timers holding the drills. They are stuck in the same goove like some ancient obsolete needle-in-groove vinyl disc recording. <shrug>

N9NWO: "I agree that we are to experiment. Generally a newbie is too focused on learning skills. It takes a while to go through the learning curve in any hobby or vocation."

That is all dependent on a 'newbie' coming in without any experience in any other radio service. With the expansion of 'radios' of all kinds into the rest of the world, amateur radio long since lost its imprimateur of 'being the starting point for all in radio.' It's no longer that way, hasn't been so for years. The vast majority of degreed professionals in
radio do NOT have, nor did they ever have, amateur radio licenses. Electronics is fascinating unto itself and will draw in folks without the trappings of amateurism.

N9NWO: "I have seen some solid state amps being developed over the last few years that are compact and lite weight. In many cases they mirror the developments (solid state) that we are seeing in broadcast transmitters."

Looking at it from a (retired from regular hours) design engineer's point of view, I would say they mirror more the finals of the many and varied PLMRS (Public Land Mobile Radio Servie) radios. Solid-state, HF to UHF, wide-ranging DC voltage in power supply. While broadcast transmitters may be more familiar to listeners, their quantities are (at best) less than a thousandth of the quantities of Civil Aviation Radio Service radios (AM on lower VHF). Toss in the Public Safety radios, the business radios, etc., etc., and the numbers of non-BC transceivers are staggering. There just isn't much demand for higher-power HF transmitters in the world; those that exist have been working for a long time. Harris Corporation might be the USA leader now. HF is becoming passe' for any NEW radio applications. HF is sustained for commercial and government use by various infrastructures that have older, but reliable equipment.

N9NWO: "Now if we could just see a drop in cost!"

Well, that's another can of worms. Market prices have so many outside influences that design causes hardly a ripple in them. With the essential non-growth of US amateur radio numbers, the boat anchor power PA equipment ought to sustain the olde-tymers for the rest of their natural lives. :-)

The amateur radio market seems adverse to any SUDDEN radical departure from The Standard Way Of Making Things. Technological developments filter in slowly. The Big 3 in Japan seem to have followed the Planned Obsolescence scheme of US auto makers of the last half
century. Hey, it works for the manufacturers and marketers. Public Relations departments of those can handle the psychological task of convincing buyers that their one brand is better than others or that an old concept is really 'new' with the proper window dressing. :-)

An external Power PA for HF is not a complex device. Its basic module is the linear amplifier itself. Why 'linear?' Because such an amplifier can handle ALL modulation types without needing any bias switching for modes. Besides, the most-used mode on HF amateur
bands is SSB AM. :-)

The old Motorola appnotes by Granberg showed How To Do It with (Motorola) RF power transistors. Everything about them, including how to make the iron powder and ferrite inductors and transformers. Those have been out for public perusal for 25 to 30 years. Heck, Communications Concepts Inc. even sells a kit of parts (including a PCB) to make some of those. Those designs WORK. They are physically smaller than comparable-rated tube designs. They operate on much lower voltages, some on just 12 VDC.

Regulated DC voltage-current supplies for 12 to 28 VDC have been legacy for decades in electronics. The only hard part of doing those is choosing from SO MANY available designs. :-) Those are also small, compact, light weight if switching supplies are used instead of
massive iron laminate transformers for 50 or 60 Hz primary AC lines. Note: There are very few toroidal core power transformers available but those can be bought in the USA or UK on special orders. If one doesn't like switchers that kind is an in-between size...but costly.

Electronic countermeasures work and vertical deflection amplifiers in Tektronix 540-series scopes used 'distributed amplifier' techniques to make push-pull wideband linear tube amplifiers between 40 and 50 years ago. Admittedly, NOT compact or light weight, using old legacy vacuum tube types, they did show that linear power amplification was possible using a very different method. I don't recall ever seeing that applied to amateur radio RF power amplifiers. Perhaps it was to 'foreign' a concept to catch on, even if compact for tube-based designs. After all, amateur radio equipment Must Be Built In Only a Certain Way...according to some olde-tymers. :-)

Real cheap construction? Hey, its possible. That would really drop market prices. Heath Company did that regularly. Lots of others did it back-in-the-days. Even renowned Hewlett-Packard did in its first models of oscilloscopes, trying to compete with Tektronix. Their HP-150s turned out to be DOGS for instruments. Took them a while to recover that share of the market. Real cheap construction and cutting features to the bone will make an INITIAL profit for a manufacturer. Heath Company eventually folded. Cheapness won't sustain them in the long run. Customers having lots of breakdowns will go to a competitor. They might even go to Ebay! :-)

73, Len AF6AY
 
RE: On taking a larger view:  
by K6LHA on June 9, 2008 Mail this to a friend!
AI2IA posted on 9 Jun 08:

"Ridicule is never an effective tool in disputation. I suggest that it be dropped."

Wise words to long-tenured 'holier-than-thou' amateur licensees, yes. :-)

AI2IA: "I suggest that those who are overly sensitive to it forget about it."

I must apologize to you directly. I didn't know you were the guardian of What We Extras Must Do or so sensitive about NON-ARTICLE subjects. Mea culpa...I've only been an ARRL member for a year and a half, haven't followed the Acts of their Good Book to the letter. I'm truly sorry that you are so sensitive to opposite opinions on NON-ARTICLE subjects. Had I known of your extreme discomfiture earlier I might have rephrased what I wrote. Or maybe not. :-)

Now, ON THE ARTICLE SUBJECT, what have you to contribute to the discussion on the DESIGN of small, lightweight RF power amplifiers for HF operation? Anything?

<questioning look>

73, Len AF6AY
 
Most relevant to this thread.  
by AI2IA on June 10, 2008 Mail this to a friend!
My intention has been fundamental:

My point for sincere hams who are interested in RF Amplifiers is simply this:

You must first answer for yourself the question "Why?" before you go on to explore the question "How?"

- Ray Mullin, AI2IA
 
10-Pound 700-Watt Automatic Amplifer  
by AI2IA on June 10, 2008 Mail this to a friend!
My style is clear.

For the newcomer who is puffed up with what he thinks are his superior non-amateur accomplishments relative to amateur radio,and who attacks me without provocation, my position is this:

"The patient man is better than the warrior, and he who rules his own spirit is better than he who takes many cities."



 
RE: Linear Ampliers and Qualifications to Use  
by N9NWO on June 10, 2008 Mail this to a friend!
The reason that we have incentive licensing is that it would be difficult for most people to go from knowing little to being fully qualified. Given the freedom that we have in amateur radio there is a lot of responsibility as part of our license.

At a 1000W you have the ability to do harm far easier than at 100W or even 5W. In the military I can use the power of command (orders) to limit power (try using too much power on a military satellite and see how fast you have general officers wanting your hide).

Thus I see using a power limit as a more reasonable distinction of operating class than restricting what frequencies one can transmit on. If an individual has a lot of civilian training and/or experience then they can pass all of the tests in one day. If they do not then they may take a while.

I also fly. Pilots have a form of incentive licensing. With 20 hours of training, one can fly as a Sports Pilot. At 40 hours one is Private Pilot. Then there is the Instrument Rating, Commerical Pilot and Multi Engine. Often insurance companies will not allow you to rent a multi engine plane until you have 250 hours of flight time.

Both the FCC and FAA have given their respective users the power to test locally. However would you want hours of training like the pilots have just to get your license? We have a shortage of pilots, especially in GA, due to the young being unwilling (and often too poorly educated) to do all of the hours of training. The "payoff" just takes too long for the amount of work in both of our hobbies (and nearly half of the kids are now not finishing high school, 74% can not get into the military under any condition@!).

I think that the FCC should use power rather than frequency as the privilege to encourage upgrading. I want people in the hobby (and too many old farts are of need of a hobby). But, like flying, one can do a lot of damage until one gains experience. If you do have that experience then it is possible to go right to Extra without passing through the other licenses, so what is the beef?
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by N5LRZ on June 10, 2008 Mail this to a friend!
I echo the reply of the poster who said focus on a good antenna system and forget the big amp. If you antenna cannot hear that DX station then all the amps in the world will not help you.

As to the price...

If you want an amp but find them too expensive, remember this. Having a Amateur License does not grant you a right to an amp.

Save your $$$$ and buy one using your own money just like everyone else.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K6LHA on June 10, 2008 Mail this to a friend!
AI2IA leafed through Bartlett's Familiar Quotations and came up with this on 10 Jun 08:

"My style is clear.

For the newcomer who is puffed up with what he thinks are his superior non-amateur accomplishments relative to amateur radio,and who attacks me without provocation, my position is this:

"The patient man is better than the warrior, and he who rules his own spirit is better than he who takes many cities."

-------------------------------

Old philospher Confusion said: "Man with one-track mind often get train of thought derailed."

73, Len AF6AY
 
RE: Linear Ampliers and Qualifications to Use  
by K6LHA on June 10, 2008 Mail this to a friend!
N9NWO wrote on 10 Jun 08:

"The reason that we have incentive licensing is that it would be difficult for most people to go from knowing little to being fully qualified."

In general terms that MIGHT be true. Problem is, "most people" is rather ambiguous and without any standard other than a general basis being the people you know. Many people that I know have been IN the electronics field for a long time and are fairly skilled in many electronic things. Many other people I also know don't know squat about electronics ('radio' is a subset of electronics). Its a mixed bag of people-with-many-knowledges in this time...it isn't like it was in 1934 when the FCC was created.

N9NWO: "Given the freedom that we have in amateur radio there is a lot of responsibility as part of our license."

Yes, but I posit that it has NO MORE responsibility than MANY other very ordinary things we do every day...and, in that same vein, the amateur radio license involves LESS RESPONSIBILITY! [I am looking at the overall picture not any pomposity usually seen/heard among long-timers 'federally authorized' for decades in an amateur avocation]

N9NWO: "At a 1000W you have the ability to do harm far easier than at 100W or even 5W."

Well, you have to define 'harm' a bit finer than that.

Yes, a full gallon can do more RFI than any QRP Tx insofar as affecting other people. Other than due to accident to any owner-user of a ham high-power Tx, there doesn't seem to be any danger of any RF killing a 'civilian' (non-radio person). Taking of life is, to me, about the greatest HARM that anything can ensue.

EMOTIONAL upset is, to me, a very low-on-the-scale sort of 'harm.' Yes, blotting out some neighbor's favorite TV program via RFI will cause them a lot of emotional upset, but they suffer NO physical danger as a result. You may as a result if the angered neighbor decides to attack you as a result. :-) <shrug>

N9NWO: "In the military I can use the power of command (orders) to limit power..."

The US military has the main mission of 'closing with and destroying the enemy.' Every other skill in every military branch is subordinate to that, exists to enable the main mission. It is non-applicable to any civilian AVOCATION.

N9NWO: "Thus I see using a power limit as a more reasonable distinction of operating class than restricting what frequencies one can transmit on."

Let's give that a PRACTICAL test, looking at it from the FCC's point of view in regards to ENFORCEMENT OF REGULATIONS.

In the present state-of-the-art in electronics, receivers can hear/see any frequency used in 'radio' to a very accurate value. Extremely accurate even with less-than-state-of-the-art frequency accuracy. The strength of a signal, more rather the amount of RF energy received at any one place could vary as much as 120 db in power, yet the measurement of frequency can be done to the same accuracy over that whole range (a ratio of one BILLION to one). Measuring RF ENERGY by means OTHER than direct connection with calibrated test equipment is quite another problem.

Frequency can be 'easily' measured remotely. Trying to measure RF POWER accurately by a regulatory agency requirs agency representatives to be VERY CLOSE to the RF source...even right up to a property line (if no search warrant has been obtained). Those representatives must use known-characteristic antennas, properly sited and away from conductive/absorptive objects nearby, in the 'far-field' (greater than 5 wavelengths) for most accuracy (by present common metrological methods). Even then the accuracy of RF POWER measurement is disturbed (in common residential areas) by parasitic effects of nearby conductors such as power distribution lines, various metallic structures (water pipes, sheet metal in rain gutters to patio covers, etc.), various partially-absorptive plant growth. Trying to get an absolute accuracy (which law courts demand) is VERY DIFFICULT in measuring RF power as compared to measuring RF frequency.

The much-older amateur radio regulation used a DC power input (to the final amplifier) as a criterion. By comparison to today's regulations, that was a 'no-brainer.' Nobody needed to be an expert in fields and waves to measure that. A Simpson multimeter with a current shunt kit could do the 'technical' task. :-)

But, enforcement of RF power output can only be done reasonably close to the RF emitter that is being measured. Let's say around 100 to 500 feet from the emitter for comparison to RF frequency that can be measured hundreds, even thousands of miles away. Which would be easier for a regulating agency, use a few remotely-located monitoring stations (which can be unattended) to measure frequency...or have hundreds of agency inspectors using hundreds of thousands of test equipment in mobile equipment? The latter would result in many more millions of annual budget dollars to measure RF power from hobbyist/avocational emitters.

A compromise could be, and is partially done, by market limitations on what can be sold interstate insofar as RF power emission possibilities from a product. 'Type acceptance' isn't a technical answer nor does it 'solve any problems.' It may have the political appearance of 'solving problems' but only to politicians who are not technical experts and, if they are, must contend with many other politicians and their constituency who are not technically knowledgeable.

A power limitation by license class may look good on paper...especially to those who will never be affected by any limitations imposed on 'lesser' classes, but it can't be practically enforced.

N9NWO: "If an individual has a lot of civilian training and/or experience then they can pass all of the tests in one day."

I disagree based on hundreds of statements by long-time licensed radio amateurs made over the last ten years. They say "anyone can MEMORIZE everything," the present-day tests "being so simple!" :-)

While this is NOT in the article subject category, I can't resist a comment. :-)

I've been a hobbyist in electronics since 1947...a pro in communications since 1952...first FCC license (commercial) granted 1956...and a retired electronics engineer at the end of January 2007 when I decided to get an amateur radio license. I printed out ALL three question pools available at www.ncveg.org, put them in a loose-leaf notebook. I studied every single question AND examined the 'distractor' (but wrong) answers. There were a total of 1,679 questions, a ratio of about 14:1 of pool to required questions for the 120 in all three elements.

Living in Los Angeles, the entertainment capital of the world, I've gotten to know a few working actors. Some months after passing my test I asked one of the journeyman actors (who had been doing that for about 30 years) if he could memorize this sort of 'script' to do a 'performance' (doing a test), handing him the notebook. The answer was something like "Holy S***! Ya gotta be kidding!?" He was NOT a knowledgeable-in-electronics person but regularly had to memorize scripts (with much more data in them than just spoken lines) but he had done that sort of thing for a living and worked steadily in that crazy business in my 'hood.

The printed-out 2007 question pool is roughly the size of three (maybe four) scripts for one-hour TV shows. Those scripts average about 65 pages for actors' copies. It is difficult to do a comparison since, in actual shooting, lines can be changed on-the-spot and shooting isn't done in the linear progression of a play such as with stage productions. My actor acquaintence asked what the pass percentage was...I told him 70 percent or more. He considered that, mumbled something about having to do lines playing a medical expert on a soap opera (not knowing squat about medical terms), gave me an answer of "maybe." :-)

I'm not acquainted with any eidetics (photographic memories) who CAN memorize anything. Those are rare. I'd say that folks who've gotten to the stage where they are going to take a test already know SOMETHING about this 'radio' and regulations thereto. They stand a good chance to "memorize everything" and pass all 120 questions. Still, "memorizing' 14 times the number of required questions to achieve greater-than-70-percent passing is a tough task for normal folks.

N9NWO: "If they do not then they may take a while."

My four examiners in an ARRL VEC team were all extras and had been licensed for years. Two were involved in communications occupations. They had all done the 'progression' through all the various classes (in the 'approved' way according to some). They were all astounded that I, a stranger to them at the time, could do so...and at such an 'advanced age!' :-) The oldest was (chronologically) a year older than myself. :-) <shrug>

N9NWO: "I also fly. Pilots have a form of incentive licensing."

Yes, but civil aviation rules have changed a bit since I took lessons at the beginning of the 1960s. Passed my Private Pilot written but had to quit flying due to co$t. Was doing avionics design at the time and in-tune with what went on at BUR, VNY, LAX, SMA, etc locally. Still am through my scanner. Aircraft licensing is NOT applicable as a comparison to hobby radio licensing. Out-of-control aircraft can KILL, destroy things very quickly. Innocent people not involved in aviation. In the Los Angeles general area we've already had too many crashes, mid-airs, and the like than we should have (in my opinion). I've witnessed two fatal crashes with total of four lives snuffed out. I've seen three other crash sites after-the-fact that resulted in more lives lost and more destruction.

I have yet to hear of ONE similar case where 'too much RF power' physically hurt anyone not involved in amateur radio.

If you want an analogue in 'licensing,' try operating a motor vehicle. MUCH more dangerous to OTHERS. An out-of-control vehicle can KILL, destroy property. Of innocents. I still haven't heard of an out-of-control amateur radio RF power output killing someone.

Microwave oven use hasn't killed anyone that I've heard of, from high RF powers. Those run at 500 to 1000 Watt RF power levels at 2.4 GHz. No license requirements to use one in the USA. <shrug>

N9NWO: "However would you want hours of training like the pilots have just to get your license?"

Let's not go blue-skies on this 'elevation' of an amateur radio license. Or the 'responsibility' tow-behind that long-timers love to put on their high-flying achievement. LICENSING is just one of many tools used by radio regulating agencies to regulate civil radio use and mitigation of interference. That license was NEVER an academic-achievement certificate.

Amateur radio service is NOT classified as a Public Safety Radio Service. Never was. It is a de facto avocation, NOT an occupation...certainly not an activity in which the users can be paid for their services (hence the very name of AMATEUR plus the specific definition in opening regulatory text).

N9NWO: "I think that the FCC should use power rather than frequency as the privilege to encourage upgrading."

I disagree. I look upon 'licensing' in amateur radio as a rather pro-forma exercise in beaurocracy on the 112th year of 'radio.' Given my choice I would opt for NO license classes. ! Horrors, and take away all the bragging rights the old-timers have?!? :-)

That draconian change would never happen in today's (amateur radio) society. The radio dinosaurs living whole lives within class distinction would NEVER allow it! :-)

If there 'must' be discrimination, then I would accept frequency discrimination as the most practical, insofar as enforcement or unofficial monitoring is concerned.

ALL OF US must accept RESPONSIBILITY for what we do in daily life and how it affects others. It should be an intrinsic force in our individual 'regulation.' We can't expect laws to do everything. We have laws on just about everything...but they don't do much about stopping things like murder, arson, destruction or theft of property. Licensing of aircraft and road vehicle drivers doesn't stop accidents that KILL and destroy innocents. Like I've said, I've not heard of any non-radio person being killed or injured by any amateur using high RF power...so why go on about all those NON-article subjects? Because you can?

N9NWO: "...so what is the beef?"

Mine is with all those who want to drift away from what MIGHT be an interesting project in technology of electronics, that of designing small lightweight, RF high power amplifirs...by new components, arranged by new thoughts and ideas, not stagnating in the typical tar pits of "we've always done it the old way and that is the 'best' way."

Heh, maybe this is a 'changeover time' like back when the Spark-and-Coherer hams were suddenly faced with vacuum tube technology and other 'new-fangled' ideas! :-)

73, Len AF6AY
 
10-Pound 700-Watt Automatic Amplifer  
by NG2O on June 10, 2008 Mail this to a friend!
I'd buy one! I have been looking for a reliable 500 to 700 watt output amp, auto-bandswitching, QSK, 110 volt AC compatable, reasonably priced. MFJ/Ameritron comes close, but with a separate box and a lot of wires for QSK. I want it all in one box! Maybe Ten-Tec could do it. I want it to match up with my Omni VII. I'd even pay up to $1500 for it. I care less about the 10 pound size, as long as it is small and in one box.
 
10-Pound 700-Watt Automatic Amplifer  
by W5EN on June 10, 2008 Mail this to a friend!
If you build it, they will come.....
 
10-Pound 700-Watt Automatic Amplifer  
by K4AJL on June 11, 2008 Mail this to a friend!
why worry about the weight unless youre going to hold it in your lap while you talk. hihi
 
Wrong again!  
by AI2IA on June 11, 2008 Mail this to a friend!
A small aside, just to set the record straight:

"AI2IA leafed through Bartlett's Familiar Quotations and came up with this on 10 Jun 08 ...."

Len, presumption is a poor foundation for ridicule.

My quotation is from the Bible, Proverbs 16:32.

- Ray Mullin, AI2IA
 
RE: Quotations ?  
by K6LHA on June 11, 2008 Mail this to a friend!
AI2IA got self-righteously indignant on 11 Jun 08 with:

"Len, presumption is a poor foundation for ridicule.

My quotation is from the Bible, Proverbs 16:32."
--------
Oh, oh...another self-righteous long-timer gets into the walking-wounded act by anyone DARING to say anything counter to HIS RIDICULE OF OTHERS. Not only that, has to get RELIGIOUS quotations to allegedly 'prove' something.

Mullin, I've never presumed to be 'expert' on anydamnthing. In a few activities I'm adequate to good on others' scales of judgement. In this article thread I've tried to steer commentary onto the SUBJECT, viz the TECHNOLOGICAL POSSIBILIITES of designing and building a small, lightweight high-power HF RF amplifiers. That was generally IGNORED by nearly all. N9NWO and one other made at least some commentary towards that technology. Technology is cool, neat, fabulously interesting.

In the past week, I posted a personal comment to N9NWO concerning his stated opinion in here that class privileges should be given only certain RF power outputs. I disagreed with that and gave my reasons based on the practicality of regulation enforcement. I didn't quote the Bible to him. Now, in between times, YOU had to step in and give me what-for...and expected to quiet this "newcomer (to radio)" down. I didn't. Now you went Biblical to 'prove' something. Sigh.

Let us do a comparison of high-power RF on HF for communications, comparing 1953 to, say 2003. Note: HF is that part of the EM spectrum enclosing frequencies of 3 to 30 MHz. We can narrow that down a bit to just 4 to 18 MHz to pick the most-used part of HF in 1953 and also in 2003 (a few sunspots still around then).

In 1953 there were NO communications satellites. None. There was NO fiber-optic cable. AT&T was beginning the pioneering of wideband microwave communications via microwaves on land. The "shortwaves" or HF were *IT* for long-distance over-water radio communications. There were NO transistors that would work at HF using power levels above even a single Watt; vacuum tubes were used for such high power levels. EVERYONE who did long-distance HF communications used tubes to get high power...just like they did in the 1920s when vacuum tubes were first being improved. Transmitter designs generally used narrowband techniques for tuning in 1953 for some alleged "efficiency." General architecture of high power stages didn't vary a great deal between manufacturers. ANYONE who tuned up HF transmitter finals would "dip the plate and peak the grid" [currents]. Amateurs, commercials, military, government...all the same in tuning them. "Dip that plate, peak that grid"...and be sure to neutralize them power triodes!

Some HF transmitters had "add-on" power amplifiers back in 1953...just like some did back in 1933. Those add-ons could run at all sorts of input/output power levels, like 100 Watts to 10,000 Watts of RF output. A few up to 40 KW.

In 2003 radio amateurs had "add-on" RF power amplifiers too. The boat-anchor afficionados of 2003 to 2008 had vacuum tube power amplifier circuitry with relatively narrowband tuning. Each and every one of those vacuum tube PAs were/are tuned by "dipping the plate, peaking the grid" [currents]. What has changed in 50 years between 1953 and 2003 insofar as tube architecture HF power amplifiers? Only some peripherals...cabinetry, paint, logos, manual controls...it is still "dipping of the plate and peaking of the grid."

Now, you've ALLEGED that 'some' (meaning ME, really) people's military experience didn't count in radio. Okay, let's look at what I had to do in my assignement to a large (but not the largest) HF communications transmitter site beginning in early 1953. Regardless of having NO formal training on high-power RF equipment, I worked two years of nine days on a twelve day cycle, eight hours a shift of operating 36 HF power transmitters whose output ranged from 1 KW to 15 KW. Every transmitter got a QSY order at least once during each shift...to accommodate the varying ionospheric conditions. That's at least three dozen QSYs of (mostly) RTTY mode. RTTY back then needed each (separate) Exciter tuned as exact as possible for Mark and Space frequencies as monitored by a Frequency Standards group at the distant receiver site of that station. If the carrier frequencies weren't within tolerance, we would have to retune a transmitter. Everyone on the TTY order-wire loop (three different sites) saw everything the same...QSY order, acknowledgement, transmitter tuning completion notice, frequency standards measurement, acknowledgement by Control and notice that it was put into active status carrying traffic. Then the operating team would wait until the order-wire TTY would jingle again for another QSY order.

In the 1953 to 1954 period the transmitter site was on the edge of Tokyo Bay and used Japanese commercial electric power. The AC demand meter for the station read around 350 KWe on a regular basis, any shift. It was NOT a reliable electric service and we would have an AC power outage suddenly at least once a month, usually a bit oftener than that. We did have enough motor-generator sets to supply our own AC power for such contingencies. When a power outage happened, EVERY transmitter had to be checked and frequency standards had to verify each carrier frequency and spread (for RTTY)...any out-of-tolerance reading and we had to do retuning again. The new station northeast of Tokyo center had its own 600 KWe motor-generator sets for 24/7 service, no outages, but by 1955 there were now about 43 HF transmitters ranging from 1 KW to 40 KW. In both places ALL the HF antennas were wire, no fancy beams or log-periodics or anything else, just wires held up by tall wood poles, the same as for telephone lines.

In 2003 lots of (retro technology) radio amateurs use nothing but wire antennas and a few insist on using only open-wire balanced feedlines...as was done in 1953 (and before) by everyone on HF...few hams deviate from HF amateur radio bands and remain on HF until their ticket expires. It is time-stood-still (in HF radio) for those retro hams. Let them enjoy it. Been there, done that.

After a few months I got picked for HF transmitter maintenance. We had about 5% of transmitters powered-down but could be powered-up quickly if a transmitter failed. Such failures were rare and almost always as a result of one of the final's tubes going bad. Not unusual since they were on 24/7. Maintenance wasn't hard but we were always hands-on to everything inside, looking for signs of pending trouble whenever a transmitter was down. Once maintenance was finished we had to TEST it on-the-air using spare frequencies, another tuning just like any QSY. We on the maintenance team also had to go back to regular operation with the rest of the shift crew when maintenance was done.

In two years of 1953 to 1954 I estimated about 4,100 hours of HF high-power transmitter operation and maintenance at 8 hours a shift...discounting from an exact 4,320 hours for other communications equipment work at lower powers. That's roughly equivalent to 2 years of WORK of 50 weeks a year, 40 hours a week. Very few licensed radio amateurs use their radios 40 hours a week, 50 weeks a year in amateur radio communications...in 1953 and any time later.

Now you say that NONE of my particular Army radio experience is applicable? The 4 to 18 MHz frequency range is heavily used by amateurs for long-distance communications...when the ionosphere allows it. In 1953 I was operating on 4 to 18 MHz frequencies, although specifically NOT on amateur band allocations of that time, just above or below all of those. Today's amateur boat anchor power amplifiers use tubes...just like everyone did in 1953. Those boat-anchor finals STILL tune up by "dipping the plate and peaking the grid." That's the SAME for 2008 or 2003 or in 1953. Vacuum tube transmitter basic technology of 1953 is the SAME as what it is now. SAMENESS applies to everything about HF WIRE antennas now as for 1953...even for so-called broadband wire antennas touted by many now.

Yes, the Army station had MORE RF power allowed than radio amateurs did, but that concerned the designs of transmitters ONLY for beefiness of some components for higher voltages and currents plus reliability. Lose a PA in amateur radio and - at most - one licensee is inconvenienced. Lose a transmitter during a time of the Cold War and it is a direct threat to this nation's defense. Operate out of band, even slightly, in amateur radio of 1953 or 2003 and one MIGHT get a NAL mailed to a licensee days later. In the military there are a number of ways REAL enforcement makes one operate RIGHT and NOW. Such military penalties can be MUCH MORE than just the forfeiture of an amateur license.

You have stated that you were in the USAF. You've never said what you did. I've asked you, you haven't responded. I made a photo essay of my first experience in REAL radio communications on HF, given links twice to their availability by the public. Not only that, I have a witness who not only knew me then but worked at the SAME station at the SAME time, doing the SAME things I did there in the beginning: Gene Rosenbaum, N2JTV. I have other witnesses, too, but they aren't amateur radio licensees. Would they be 'applicable?'

I'm still not an 'expert' on high-power RF amplifiers, don't claim to be. I do have some experience on operating old boat-anchor tube PAs. Got that 55 years ago. Tube PAs' basics haven't changed in 55 years. The most used part of HF for long-distance communications is still that 4 to 18 MHz span, then as well as now. I've got lots more experience in designing electronics in order to get a regulary salary check. Since Army service the highest-power in RF that I've worked on was a 5 KW experimental UHF transmitter-oscillator...years ago. Doesn't count, you say? Of course not, 'real' hams STAY in HF and make fun of any amateur radio use above 30 MHz. Much of what I've done for a salary is under a blanket of trade secret stuff so I can't make nice photo essays of that. The corporations that funded them did their own publicity. I don't need the 'image' bling of that stuff...was there IN that, hands-on and all. I'm content with that.

You've sluffed it all off as 'not applicable.' I say to that, "You are FOS. Show me what YOU did that is even close to what I was assigned to do...and did for 3 years."

Now, on Biblical quotations: I'm not going to argue any of that. I don't see how it is remotely applicable to the possible design of a small, lightweight, 700 W RF power amplifier. As far as I know, GOD didn't invent radio...or even morse code. Sometimes, in reading ARRL literature, especially their PR, it sounds like the ARRL 'invented radio' or maybe H.P.Maxim 'invented CW.' That's their appearance sometimes...

I could go 3 blocks down my street and get Rev. Ralph Midtlyng's assistance on Biblical quotes. He officiated at our wedding at the same church. All I can offer is a non-denominational tagline: "Time flies like the wind but fruit flies like bananas."

Will you feel MORE 'insulted' and 'ridiculed' by that tagline quote? <questioning look>

I don't really think you have ANYTHING to offer IN the article subject, but you seem to have lots of OTHER things not on the subject. Try holding off on all that thinly disguised managerial-style back-peddling to soothe your own 'wounded' self-image. Amateur radio is supposed to be FUN, isn't it? Relax. There's LOTS of normally-unheard-from TALENT out there. I'd rather hear from THEM, possibly learn something new in the wonderful technology of electronics. That would be a treat!

Relax. "Today is the tomorrow you worried about yesterday" - anon. :-)

AF6AY
af6ay@arrl.net







 
Perhaps you will mellow in time.  
by AI2IA on June 11, 2008 Mail this to a friend!
Well now, AF6AY, you certainly have the verbosity to make a champion ragchewer type ham, if you get the necessary therapy to acquire courtesy, patience, good will, and a few additional civilities!

I have neither the time nor the interest to wade through all the blab in your most recent post, but hang in there, you will soon find your own kind here on eHam.net. There are a lot to choose from. You'll find your buddies.

As for me, well I'll just post whatsoever I wish to post. You can't censor me on here. I'll continue to contribute what I feel is relevant and simply ignore your personal comments about me in the future. You are spunky for a newcomer, but time will work on you.
 
RE: Perhaps you will mellow in time.  
by K6LHA on June 12, 2008 Mail this to a friend!
AI2IA tried to get the last word in on 11 Jun 08:

"Well now, AF6AY, you certainly have the verbosity to make a champion ragchewer type ham, if you get the necessary therapy to acquire courtesy, patience, good will, and a few additional civilities!"

Hey, up yours too... :-)

No sweat, self-righteous person, I can be civil to those who treat me with civility instead of self-righteous pomposity of a typical order-giving long-timer. :-)
..........

AI2IA: "I have neither the time nor the interest to wade through all the blab in your most recent post..."

Of course you don't. Often the REAL truth HURTS. Holding a mirror up to what you've written is never kind to the self-righteous. <shrug> Too bad, but no apologies.
.........

AI2IA: "You'll find your buddies."

Sonny, if I were looking for "buddies" I would NOT do it only on the Internet. I've used the computer-modem mode for communications for 21 years now, first on BBSs (local ones where one could meet others in-person and discuss things in more detail), then via the Internet. The Internet is for getting INFORMATION and possibly SHARING IDEAS, especially about technological subjects. Finding "buddies" solely via the Internet is NOT a good way to do it.
.........

AI2IA: "As for me, well I'll just post whatsoever I wish to post. You can't censor me on here."

I wasn't trying to do that. Do you have paranoid tendencies? Insecure? I'm not. But, you sure are trying to do the personal-insult thing to me, hoping I would be 'shamed' into leaving. Does NOT work, senor. :-)

Sonny, I KNOW lots of the tricks that the pompous and self-righteous use over computers. I've seen them try it, have met many of those in-person. In-person, they ain't all that nice. :-)
.........

AI2IA: "I'll continue to contribute what I feel is relevant and simply ignore your personal comments about me in the future."

Let me know when you 'contribute' something in-line with an article, huh? So far, in the last month, I've NOT seen anything from you in that regard. Lots of pompous poop about other personalities though. <shrug>

Can you do ANYTHING in technology? <eyebrows raised in question>
........

AI2IA: "You are spunky for a newcomer, but time will work on you."

Dang, you did it AGAIN. 'Newcomer,' huh? :-) :-) :-)

A mere 75 years of existance is what 'made' me, sonny. Time HAs 'worked on me' but even moreso, the existance of just enough self-righteous pompous poopers to show me their salesroom-smiling-civility-that-is-all-rehearsed-lines which they don't really feel nor express when they get away from their environment. :-)

"Spunky?!?" Sonny, I've been HOLDING BACK. Don't mess with either the tiger or dragon. I can be both...with or without subtitles. I have the experience. I have been tested in the formal crucibles more than once. :-)

Here's a factoid. If you want to see how "spunky" is really done, go over to the FCC website and search for my name on any of the dockets pertaining to the elimination of morse code testing for US amateur radio licensing. Just use my formal name in the Search window. Any year from 1999 to 2007. I was for elimination of the code test. Ya know what? That's what the FCC actually did, announcing its coming in a notice of December of 2006. I know its an awful lot to ask of someone who can't stomach more than a few lines of text, but you will get the gist of How It Can Be Done...and WON.

No, I'm not taking any credit. Enough folks wrote the FCC wanting the code test done. From the already-tested came barrages of vitriol heaped on all of us seeking its elimination. They thought they were Strong and In-Control. They weren't. That's legislative processes at work, sonny. It ain't the local ham clubhouse where all the Extras think they own everything and look down on lower classes. That's the REAL world arena where laws and regulations are done. Tough stuff. Either ya got the brass ones to tackle it or ya ain't.

I live in the Los Angeles area. This is the world center for the entertainment business. We've got more actors than one can shake a stick at...and some here DO that. :-) I know a few journeyman-class actors, maybe twice that number who work 'behind the camera.' Actors off-camera have plenty of EGO and, to others in the entertainment biz, they heap extravagent (even gratuitous) PRAISE about them. They call that 'civility.' To persons-in-power they express profound respect since Good Words may mean future work! It is almost always FALSE respect. They usually demean their bosses privately. They will admit that to 'earth people' (those NOT in entertainment in any way and NOT in journalism). Their public civility is usually false, their public respect is usually an act. They are, after all, ACTORS. :-)

Ya know what? I see a LOT of that same 'acting' going on in forums. I see lots and lots of pretense by a few. Anyone doing anything simple is elevated in 'praise' to be Nobel-Prize-worthy! Geez, are weekender projects in ham magazines as complex as 'rocket science?!?' Must be...all that gratuitous praise 'must' have a reason, ey? :-) :-) :-)

Now, I doubt you can submit anything TECHNOGICAL to this article's subject. You are probably one of those hams who just likes to play with your radio, yes? [note: that's an expressed Opinion followed by a Query...if you take that as 'ridicule' or an 'insult,' you have much too thin a skin to continue...sign off, go someplace else]

TECHNOLOGY means ya gotta know Laws of Physics to make things work for you. Laws of Physics aren't touched by human psycho tactics, human emotions, or human desires. Certainly not human Laws. That's a relief from the usual pshrink-rap stuff of pompous poopers pushing out Personal Insults and Control Statement Edicts. On the other hand, its a burden because one has to LEARN a heckuva lot more, stuff that is NOT necessarily intuitive. Tougher task, takes both brass ones AND skull-work, brain-wracking. Been there, done that. Still doing it. Don't expect any prize. It's for something strange: Pure personal satisfaction.

Here's a "spunky" challenge to you: Write something about the technology of making a small, lightweight 700 Watt RF HF power amplifier. Try not to deviate into being some kind of hall monitor in a kiddies' school. Too many do that. Such us unproductive. Got some brass ones?

AF6AY
 
RE: Perhaps you will mellow in time.  
by G4ZOW on June 13, 2008 Mail this to a friend!
I've yet to completely finish reading this thread but I though I had to add my 2p to the anti transistor lobby.

Where do you get your 60c per watt price from?

I know 50v is not suitable for many of the modern higher voltage fet's but 20c is nerarer the mark for mass produced switching supplies.

We use this one from Murata: http://tinyurl.com/6ortl9

The 1600w output version of this switcher runs our 1kw output FM broadcast PA in continuous duty cycle without complaint.

Cost $250.00

Phil G4ZOW
www.broadcastwarehouse.com
www.bwbroadcast.com

 
10-Pound 700-Watt Automatic Amplifer  
by NO9E on June 15, 2008 Mail this to a friend!
Giorgio IN3IEX wrote:

This is what I have made in the field of portable HF power amp:

http://www.elmarx.com/fontana/liexnear.pdf

It is tube based. The power supply is almost weightless, and perfectly safe.
The power supply concept is very good and rugged, the insulation is on the RF side.
The output impedance of the six tubes is low, usually I do not retune when roaming a band.

For MOSfets we could produce 50 V from 110 or 220 with SCRs, then some filtering and inductive power factor correction on the 110 (220) V only with capacitors. Insulation must be on the RF side like in my tube amp.

Every time I move my HF linear from one place to another and I recall in my mind that it "handles" 2 kW I am always surprised.

Yes, It works !

Best Regards

Giorgio IN3IEX
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by N7DC on June 16, 2008 Mail this to a friend!
I havent gone thru the multitude of responses, but what is wrong with simply buying an Ameritron (or a couple of other manufacturers) small solid-state amps? They are small, light weight, and some even come with 1 kw outputs. My als500 runs all the power I need, and I simply run it, in the house, on a deep-cycle battery, which I recharge about once a week. Have only had it online for about a year now, and with 336 countries worked, havent had much chance to put it to use for a new one, but it does just fine for 160 and makes a difference in a big way, on that band.
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by AB2JL on June 16, 2008 Mail this to a friend!
someone should investigate using IGBT's in a power amp. these things are easy to drive and are dirt cheap,

phil AB2JL
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by AC5WA on June 18, 2008 Mail this to a friend!
Finally, at long last, someone gets back to the subject of the discussion.

Insulated gate fets are a great candidate. They are becoming cheaper and gaining higher voltage and frequency specs.

What we should be talking about is using FETs in other than the old standard amplifier classes. It would be a shame to restrict ourselves to the old A, B, AB & C classes.

What about high efficiency types like class D & E? Those allow the use of much smaller heat sinks and are perfectly usable with FETs.

If the available devices will only work on 160~40M then why not build for those bands? We ARE at the bottom of the sun spot cycle after all.

The switching noise should be as easy to dump as the harmonics. The technology for automatic tuning is readily available. Roll in these new technologies and you can have a KW in a IC-706 size box.

I don't give a fig about incentive licensing, this discussion is supposed to be about amplifiers and that is what it should be about.

Have FUN!
Gerald
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K2ACB on June 22, 2008 Mail this to a friend!
Several years ago SGC advertized in QST and other HAM periodicals a mini amplifier.It was modular and compact and operated in class E.
I actually saw a prototype of that amplifier at the Dayton Hamvention. I asked the SGC people when they would market this amplifier. They said they were having some technical difficulties and they hoped to market it within the next few months.

I later heard that the owner of SGC had died and the new owners of the company had decided that they did not want to market this amplifier.Perhaps they felt that it was too difficult to overcome the technical difficulties or that it was not economically feasible.I do not know the answer.

I understand that the Class E type amplifier was developed by a radio amateur WA1HOC in 1976 and he has the patent. Today it is used in satellites.

Was the SGC mini hf amplifier that was advertised several years back ahead of its time? Can a mini amplifier like the one SGC advertised be made for the radio amateur market? Can such an amplifier be used for mobile operation? I do not think the SGC amplifier could be used for mobile operation.Could such an amplifier be made to run more than 500 watts and still be small, lightweight and compact? I

I am curious if anybody has any input on small class E amplifiers for the radio amateur market. I have also posted a similar message in the forum section on amplifiers on e ham.net. 73-Alan-k2ACB
 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K2ACB on June 22, 2008 Mail this to a friend!
I made a mistake. I understand the person who holds the patent on the class E amplifier is Nathan Sokol. His call is WA1HQC.I cited his call incorrectly. He patented the class E amplifier sometime in the mid 1970's.
The SGC mini amplifier was modular.You had to put in a module for each band. It was a 500 watt amplifier and SGC indicated it could not be used for mobile operation.

Again I wonder why other amplifier manufacturers for the radio amateur market have not pursued marketing a small, light compact class E amplifier running a minimum of 500 watts? Is it not technically feasible or economically not worth it?

I have also posted a similar post in the amplifier section on e ham forums. 73-Alan-K2ACB

 
RE: 10-Pound 700-Watt Automatic Amplifer  
by K6LHA on June 22, 2008 Mail this to a friend!
K2ACB posted on Class E PAs on 22 Jun 08:

"I made a mistake. I understand the person who holds the patent on the class E amplifier is Nathan Sokol. His call is WA1HQC.I cited his call incorrectly. He patented the class E amplifier sometime in the mid 1970's."

You will find that the Sokols (plural) were granted several patents on the method. The time frame might also include the 1980s. [been a while since I perused those...]

All are technically interesting but require active components/switches that work much faster than the period of one RF cycle at desired frequency...and in handling power. Those two requirements tend to be mutually exclusive.

In today's consumer market, audio power output stages use transformerless Class D finals, a very (relative) high frequency squarewave modulated in width by the audio, that followed by a simple lowpass filter. Inexpensive, on the scale of transformerless Class B biased solid-state amplifiers but having less power demand therefore less cost for cooling and in a smaller size. Class E is a refinement of Class D.

The Class D technique isn't new. In a 1950 microwave radio relay terminal, GE channel demodulators had a width-modulated 8 KHz pulse output that was sent directly into a lowpass filter with 3 KHz cutoff. Filter output was the reconstructed audio with very little overall distortion. With 24 channel demodulators per terminal the method proved less costly than comparable techniques. Audio is one thing, RF is considerably faster.

One way to run Class E is to start with a pulse having a repetition rate of the RF carrier, then amplitude-modulate it by pulse-width modulation or frequency-modulate it by variation of the pulse repetition rate. At 20m, the repetiton rate of an RF cycle is 71.4 nanoSeconds (or 0.0714 microSeconds) and one degree of the carrier wave cycle is 198 picoSeconds (0.000 198 microSeconds). That's a bit beyond the times involved with common (but fast) digital logic devices.

The refinements with Class E can 'play tricks' with integrating other devices such as passive filters of a specific kind and the connection of gates in the active devices. What is possible is an RF output v. DC input power efficiency better than Class C. But, there is still the harmonic output problem where, however efficient the design may be, harmonics can be beyond FCC limits for USA use.
...........

K2ACB: "Again I wonder why other amplifier manufacturers for the radio amateur market have not pursued marketing a small, light compact class E amplifier running a minimum of 500 watts? Is it not technically feasible or economically not worth it?"

A Class B RF power amplifier of the conventional solid-state design is already small and simple, having fewer components (as of right now) than either Class D or E presented designs. Linear amplification is straightforward and more understandable to the average amateur potential customer than some 'newfangled' IC-managed non-linear technique. The amount of efficiency improvement versus extra cost doesn't seem to be worth it...at least at the present state of the design art in this area.

The cooling needs and life expectancy of conventional Class B Linears is now well known and cooling can be handled with a great variety of low-cost air movers available in the consumer computer market products. It would make more marketing sense to go with what is known and dependable in making a profit than to try something radically different with little improvement over the present profit margins.

A better area for improvement is the DC power supply for such a Linear (of any type) and that can be accomplished via a variety of techniques, primarily using switchers. Switchers allow better control over the AC primary power input's power factor (green techniques) that has less of an effect on the remainder of a residence AC power distribution. Theory on that is now well-known and components plentiful on market.
..........
On your previous message, the major RF amplifier technique in communications satellites is the TWT or Traveling Wave Tube. Those work at microwave frequencies but can cover a whole octave of bandspan. Efficiency of RF power output v. DC power input is poor but the amplified output is linear and it can work directly into any low-impedance system over an octave and not need any extra RF filtering. All commsats work at microwave frequencies.

73, Len AF6AY
 
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