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Author Topic: Choosing a Legal Limit Amp  (Read 20826 times)
K7KBN
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Posts: 2825




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« Reply #45 on: April 22, 2013, 11:02:19 PM »

Reminds me of a QST article from the early 60s.  Written by John Troster, W6ISQ (SK), it was a tongue-in-cheek look at "California Kilowatts".

One of the comments allegedly overheard on 75 meters was about the Collins KWS-1:  "It sure makes a dandy exciter for my amplifier!"

Another paragraph noted that a true California Kilowatt station uses silver dollars for key contacts...
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73
Pat K7KBN
CWO4 USNR Ret.
K6AER
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Posts: 3528




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« Reply #46 on: April 23, 2013, 12:10:45 PM »

The new Alpha amps don't go much over the legal limit. My 8410 would only do about 1900 watts. My buddies 9500 was about the same.

As for 8877 degradation, the tube will produce 1500 watts easily for 35 years. Key is not to exceed the grid current rating.

I would perfer to have an amplifier with at least 2-3 dB of head room. IMD will be much better with complex modulation.

Despite popular wisdom most 911 turbos just follow the car in front of them.
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N4ATS
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Posts: 845




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« Reply #47 on: April 23, 2013, 02:22:17 PM »

Despite popular wisdom most 911 turbos just follow the car in front of them.

Soooo true

Bill
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W5ZL
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Posts: 11




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« Reply #48 on: April 26, 2013, 01:28:32 PM »

Currently, I have 4 amplifiers.  The AL-811, a Heathkit SB-220 a converted SB-221 to 6M and an Alpha-9500 with an Alpha-4510 Power/SWR Meter which I have had for the past year and a half.  Before Alpha-9500, I had an Alpha-87A for about 3 years.  At this point, I have to force myself to use one of my other amps, otherwise, I would never turn on anything except the Alpha-9500; it is a sweet machine to operate.  The Alpha-9500 couldn't be easier to operate.  All you have to do is select the band on your Exciter, reduce power to about 15 watts out of the exciter, press the "Auto" button on the Alpha-9500, send a continuous wave signal from the exciter, bring up the exciter power to about 42 watts and you will be at 1500 watts PEP when you switch to SSB.  Turn off the "Auto" feature of the Alpha-9500 and begin to call CQ.  I know of some operators that tune/load their systems using the Alpha-9500 without starting out with low power, they set their exciter to about 45 - 50 watts and start talking SSB and let the firmware tune the Alpha-9500; personally, I don't see any reason to stress a piece of equipment just because it will take it.  I don't think you can find a better automatic tuning RF amplifier for the money anyplace.  It is my opinion that the Alpha-9500 is a lot sweeter tuning amplifier than the Alpha-87A; but, that is just one Old Man's opinion.

Good luck with the decision on the amplifer you finally decide to acquire.
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VK2ANS
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Posts: 6




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« Reply #49 on: May 01, 2013, 06:02:14 PM »

Hi Guys, re the new THP HL-2500FX model; I last visited the THP factory last October and saw they had delegated mostly one engineer for each new amplifier model's development, with five or six amplifiers being under development. THP's best RF engineer, "the RF genius", is developing their new HL-2500FX. THP chose to change over to THP2933s because using six of them should (in their opinion and experience) prove to be much more rugged and reliable than continuing to use two ARF-1500s. The added bonus is the new HL-2500FX amplifier would also operate up on 6m, unlike the HL-2.5KFX. This new amplifier should be available soon, but I haven't checked with THP for a few months in this regard.
Lee. VK2ANS.   
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KC4MOP
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Posts: 753




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« Reply #50 on: May 03, 2013, 07:47:14 AM »

I am thinking that the rage for MORE QRO is that there seems to be a lot more inconsiderate operators on the air now. The ops "playing the game" have to deal with tuner-uppers and ops who like to "Hold the Frequency". Complete silence until you ask if the frequency is in use and then they start to chatter. Or 250khz of band space and QSO's are happening within a 1kc of each other. It takes about 3-4 khz spacing for SSB, and 6khz, for an AM QSO. But no, you hear an AM QSO and there's SSB ops trying their damndest to talk over the AM QSO, either on freq or within 1 khz of the AM QSO.
I know it's a losing battle that whomever can put out the largest signal and be the channel master is the one who wins. Seems like a CB mentality.
Legal QRO, and make improve the antenna.
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AD9DX
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Posts: 1507




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« Reply #51 on: May 06, 2013, 08:33:31 PM »

Thanks for all of the comments and advice.

I bought an Alpha 8410 at the Visalia DX convention over the weekend. The show special was a free set of spare 4CX1000A tubes for the amp.

I am sure you are loving it. I have an Alpha 76a that I sent to Dick Byrd to have it converted to use a pair of 3cpx800a7 tubes and a QSK relay. My previous amp was a Heathkit SB-200 and I couldn't be happier. Unless I can some day find a Alpha 87a or 9500 for cheap, it is the last amp I will e er have to buy.

I am sure that your 8410 will suit you the same way.
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EX, KC9TRM, KB9IRZ
KA7NIQ
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Posts: 260


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« Reply #52 on: May 19, 2013, 07:41:33 PM »

8877's have a finite life based on cathode emissivity and it degrades over time regardless of being in standby or transmitting. Two tubes will last as long as one at legal limit. Also one tube can do 1.5kw 24/7 with ease if power supply is up to duty cycle too. You do not need two to do 24/7 but you do for 3kw and more 24/7.

My friend has a car that develops 600 HP -- do you think that's excessive too since the speed limit here in California is 65-70 MPH?

Not the same. I have owned muscle cars in past too and played with them on strip but they did not perform well on street legally. The is only one reason to build/have a amp with two 8877's or three 3cx800's is because you plan to use the extra power regularly but far be it for anyone to openly admit doing it. I here a guy on 40m sometimes that is clearly running excess power and splattering all over too and get away with it but it does not make it right. Sorry if I seem a downer on this but I am "old school" and play by rules even when others do not.
Thanks for saying, what needed to be said!
Too many Hams these days are running FAR in excess of Legal Power, and to make things even worse, these LIDS are widening their transmit bandwidths, all in the name of so called "Hi Fi Audio" (ESSB), and splattering away.


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KA7NIQ
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« Reply #53 on: May 19, 2013, 07:54:32 PM »

And ask them about what? What the "limit" really is? They make good money of amps that will exceed legal limit easily so what do you think they are going to say?  Duh...

I'm surprised you can still walk with a chip on your shoulder that is as big as the one you carry.

No chip, just old school and do not like companies that exploit loop holes for profit. Truth is though they pretty much gutted FCC enforcement in first part of last decade and commercialized Ham Radio by removing code requirement to boost sales and profits. If you have the coin you can by any amp you want for ham use it seems.   Funny thing is for years they slammed CB for running amps and yet amps that that can make "illegal" power for ham use are okay. Bizarre   
Yeah, they blasted CB'ers for Roger Beeps and Echo Boxes, yet some of these ESSB Lids  are using a "touch of reverb" with bandwidth so wide, they occupy BOTH sidebands!
It has gotten so bad on 75 meters here in Florida, that power outputs far in excess of legal power are openly talked about.
Though these LIDS are already S9+ with 100 watts, they will run far in excess of legal power, even when conditions do not warrant it.
Speak your mind W8JX, I hear you, loud and clear!

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ZENKI
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Posts: 980




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« Reply #54 on: May 20, 2013, 04:42:56 AM »

Nobody mentions how important  the issue of spectral cleanliness of amplifiers. Tubes and solid state amplifiers with poor IMD performance should really be placed at the bottom of your list.

You cant rely on the ARRL reviews to tell  you how clean the amp is. The ARRL simply ignores the issues and does not care if the AMP Is dirty. Every piece of crap spewing out IMD garbage is OK by them if they review it.
 An example is  the review of the Acom 1500 amp in this months QST. -27db 3rd order  and -49db 9th order. Rather unspectacular figures yet they say nothing about such amplifiers. A 8877 as comparison has superior IMD performance. The current batch of solid state amplifiers are also rather poor performers but the ARRL just keeps on reviewing like everything is well. Hear no evil see no Evil!

If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.




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AD9DX
Member

Posts: 1507




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« Reply #55 on: May 20, 2013, 05:40:21 AM »

Nobody mentions how important  the issue of spectral cleanliness of amplifiers. Tubes and solid state amplifiers with poor IMD performance should really be placed at the bottom of your list.

You cant rely on the ARRL reviews to tell  you how clean the amp is. The ARRL simply ignores the issues and does not care if the AMP Is dirty. Every piece of crap spewing out IMD garbage is OK by them if they review it.
 An example is  the review of the Acom 1500 amp in this months QST. -27db 3rd order  and -49db 9th order. Rather unspectacular figures yet they say nothing about such amplifiers. A 8877 as comparison has superior IMD performance. The current batch of solid state amplifiers are also rather poor performers but the ARRL just keeps on reviewing like everything is well. Hear no evil see no Evil!

If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.






My god this is the same topic you have posted in at least two different threads this morning. Why not try writing a letter to your senator.  The amps discussed meet or exceed FCC requirements. If you want companies to do better, petition the FCC to change their standards. 
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EX, KC9TRM, KB9IRZ
W5JON
Member

Posts: 174




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« Reply #56 on: May 20, 2013, 06:17:53 AM »

Nobody mentions how important  the issue of spectral cleanliness of amplifiers. Tubes and solid state amplifiers with poor IMD performance should really be placed at the bottom of your list.

You cant rely on the ARRL reviews to tell  you how clean the amp is. The ARRL simply ignores the issues and does not care if the AMP Is dirty. Every piece of crap spewing out IMD garbage is OK by them if they review it.
 An example is  the review of the Acom 1500 amp in this months QST. -27db 3rd order  and -49db 9th order. Rather unspectacular figures yet they say nothing about such amplifiers. A 8877 as comparison has superior IMD performance. The current batch of solid state amplifiers are also rather poor performers but the ARRL just keeps on reviewing like everything is well. Hear no evil see no Evil!

If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.






My god this is the same topic you have posted in at least two different threads this morning. Why not try writing a letter to your senator.  The amps discussed meet or exceed FCC requirements. If you want companies to do better, petition the FCC to change their standards. 


AD9DX,
Thank you , thank you, I also have become very tired of Mr. (I have no callsign), (one tune) Zenki.  To him IMD is the ONLY thing that matters, and his one man campaign of criticizing almost every amplifier made today for IMD is getting real old. Zenki, you have made your point HUNDREDS of times, give it a rest. 

John  W5JON  -  V47JA 
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W6UV
Member

Posts: 540




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« Reply #57 on: May 20, 2013, 08:03:21 AM »

If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.

Zenki,

Your comments would carry a lot more weight if you posted your call sign (as you claim to have) rather than hiding behind an anonymous screen name. If nearly everyone else on eHam posts using their call sign, why can't you? What do you have to hide?
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K5RT
Member

Posts: 160




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« Reply #58 on: May 21, 2013, 04:25:26 AM »

I'm wondering if Zenki might be WB2WIK. To me, his words (not to mention this subject), sure sound like Steve talking.
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K6AER
Member

Posts: 3528




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« Reply #59 on: May 21, 2013, 02:42:47 PM »

Trust me Steve is not Zinke. Steve is proud of his call and has been a ham for too long to go chasing windmills.
« Last Edit: May 21, 2013, 02:46:25 PM by K6AER » Logged
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