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Author Topic: Suggestions for a 100 Watt Class amplifier for a FLEX-1500?  (Read 22690 times)
ZENKI
Member

Posts: 906




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« Reply #45 on: April 13, 2013, 08:19:18 PM »

We should really be optimizing amplifiers for  optimum occupied bandwidth rather than  best 2 tone numbers.  A spectrum mask should be used under voice or white noise loading for minimizing higher order IMD products.
This is essentially what the ITU and FCC uses for their type acceptance standards.

There are  a number of ham transceivers with excellent 2 tone 3rd figure yet they could not even pass the FCC part80 marine standards because they have such lousy high order IMD suppression. The suppression of high
order IMD and problems like  ALC induced splatter overshoot is the issue that needs to be addressed in  ham transceiver design.  Even if we did have the perfect transceiver what point  would it be having such ideal equipment when we have hams who have every intention of using their CB equipment on the ham bands.

We have these idiotic practices now creeping into the ham service that causes massive amounts of interference. Badly adjusted  ESSB equipment and  the use of CB amplifiers  is a malaise  that is causing a lot of interference.
Its just unfortunate that these two bad operating practices seem to appeal to many new hams and CB'ers. ESSB as practiced today is the CB equivalent of running excessive microphone gain. CB'ers were at least smart enough to do it with equipment that was worth 50 dollars. ESSB users cause the same amount of splatter and do it with  equipment  worth 1000's of dollars.


I've done a lot of experimentation with homebrew HF amplifiers and, across all of the designs, one thing stands out. The higher the source drain voltage (or emitter collector) the cleaner the amplifier. I don't know the theory behind this but empirical results have shown that a 48V amplifier is a much better beast than a 12V one.

One other thing helps. About half of the amplifiers have a center tap on the output transformer and use this to feed the DC into the amp, this increases IMD by a small amount but reduces costs and PCB board space. A separate DC feed through a bifilar transformer is the only way to do it.

Tanakasan
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WD5GWY
Member

Posts: 391




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« Reply #46 on: April 13, 2013, 09:51:13 PM »

ZENKI, thank you for posting the numbers(finally).  I understand what you are
trying to say. It was never my intention to defend the use of RM Italy amps.
I simply wanted to know what your measurements were and how you arrived at
them.
   I know that if someone is using one of those amps, that the temptation to drive
it to full output would probably be quite high. But, I will say this, that on their website
that the input stated for them (HLA-300) is 2 to 20 watts, not 20 to 25 watts. So, at
at anything over 20 watts you were overdriving it. And creating even more splatter. And, if I understand things correctly that would skew the results of your tests. I have heard them on
the air in the past and have tuned up and down the band from them and could not hear any
splatter from them. Nor could I see it on my Flex 1500's bandscope. I know that using the
1500 as a means to try and see something like that is limited, but, I have seen splatter from
people using other amps that were overdriven and had things like the mic gain set too high.
 So, I know that I can see that sort of thing with my current setup.
Oh, and I have heard someone using the HLA-300 and overdriving it too. But, only once. And
when I mentioned it to him, he did get a bit upset about it. Not surprising really. But, he eventually did back the drive down and it did seem to clean up pretty good. At least, I could no
longer detect(hear and see) splatter that I could actually ID as being from the same station,
while tuning up and down from his signal. Of course, he probably ran the drive back up at some
point later on!
   As for the FCC's Marine Standards for HF radio being applied to Amateur equipment, do you
really think that will happen? It would be nice. But, I wonder if the FCC even cares about that?
As long as the Amateur Service does not interfere with other services, I doubt they do.
It would be up to Amateurs to insist that manufacturers provide better quality transmitters.
IF they cared about that. But, my bet is that won't happen either. One reason being that it
would add to the cost of Amateur gear.
   I don't know about where you live, ( I have thought you lived in Europe) but, here in this
country, I rarely ever hear of anyone using CB equipment(amplifiers) on the ham bands.
Companies like Amertron make inexpensive, but well designed amplifiers that work well on
the ham bands when used properly. And then there are even more expensive amps that do
even better. BUT, again, I have heard hams using some of the most expensive equipment
out there and have horrible signals because of poor setup. There are a lot of hams now that
do not know or understand how to properly set up their radios. I believe that is more of a
problem than the few who try to use amps such as the RM Italy.
The RM Italy amps, ( HLA & BLA) are not that easily available and are known to not handle
very much in the way of high SWR without going into bypass mode. Amps like the Ameritron
811H are much better. Even Ameritron's solid state amps are better. But, like anything else
driven with a transceiver that is not set up correctly, it will create problems.
  I think the biggest problem is lack of education in the Amateur community.
It would be nice if Amateur clubs would offer classes to new hams that helped them understand
their equipment better. And how to use it properly. That would do more to clean up the bands
than anything else.
james
WD5GWY

Again, thanks for your input. I was not accusing you of running away. But, it has seemed to me
in the past that if someone asked you a more pointed question you would not answer. I'm glad
you decided to respond to my questions.
   
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AD6KA
Member

Posts: 2232




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« Reply #47 on: April 13, 2013, 10:02:37 PM »

Quote
I think the biggest problem is lack of education in the Amateur community.
It would be nice if Amateur clubs would offer classes to new hams that
helped them understand their equipment better. And how to use it properly.
That would do more to clean up the bands than anything else.


I don't mean to be a curmudgeon, but based on the
questions we see posted on forums by Newbies (and some
others) it seems that most won't even RTFM!  Grin
So you think they would actually take the time
to attend a class?
It's a good idea, and I wish it were so, but.......I have my doubts.
73, Ken  AD6KA
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WD5GWY
Member

Posts: 391




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« Reply #48 on: April 13, 2013, 10:23:31 PM »

Quote
I think the biggest problem is lack of education in the Amateur community.
It would be nice if Amateur clubs would offer classes to new hams that
helped them understand their equipment better. And how to use it properly.
That would do more to clean up the bands than anything else.


I don't mean to be a curmudgeon, but based on the
questions we see posted on forums by Newbies (and some
others) it seems that most won't even RTFM!  Grin
So you think they would actually take the time
to attend a class?
It's a good idea, and I wish it were so, but.......I have my doubts.
73, Ken  AD6KA
That may well be true. If some clubs were to offer classes, it might
just work, but, if no one ever does, then no, it will never work.
The license classes offered by several local clubs seem to be well attended.
So, why not give classes on setting up radios, antennas etc.?
And as far as newbies asking questions, answer them. I know some are really
basic and make you scratch your head and say," didn't you learn that when you
studied for your test?" But, with no one even trying, then there will never be any
change at all.
Thanks for your input. All curmudgeon's are welcome!!!
james
WD5GWY

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K6AER
Member

Posts: 3488




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« Reply #49 on: April 14, 2013, 09:11:41 PM »

“When i  measured the HLA300 not  with 2 tones using white noise loading using a IC706 and  HLA300 the IMD was disaster at fully output. The IC706 was putting out between 20 and 25 watts for about 300 to 400 watts across all the bands. Thats  about the manufacturers ratings and where most hams would be running them not at 200 watts. Why would spend money on a 400 watt amplifier and run it at 200 watts?  No normal ham would do this. Its a nice feel good argument for hams who buy this CB splatter garbage  and then run the amp at full power. Everyday on the ham bands we hear these crap boxes spewing out splatter and  occupying 20 khz of bandwidth with splatter  when they drive to the full rated output.”

The HLA-300 uses 4 SD1446 80 watt transistors. Why would you try to get 300-400 watts out of an amplifier that is in compression at 300 watts out?

What was your Amplifier Vcc voltage during the test?

What was the occupied bandwidth from the driving  transceiver?

How did you mesure that bandwidth?

What instrument did you measure the bandwidth with?

I still don’t see any hard numbers.
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ZENKI
Member

Posts: 906




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« Reply #50 on: April 20, 2013, 06:50:48 PM »

All good questions Mike.  I can  answer all of them.

 Your original contention was that the amp was "clean" at 200 watts. Maybe in your hands only! You have technical ability others dont.  My point was that the typical ham does not run this amp anywhere near 200 watts from a mobile or home station. They always drive these amps to the limit because they looking for a cheap amp with high output. I can  almost guarantee that every ham using one of these amps is driving this amp to a power output level of between 300 and 400 watts. They will even describe their RM power output on their QRZ profile. In Europe this is the output power that most hams are running these amps for mobile or home station use. Every  time I hear splatter and query the stations who use these amps this is the power they running the unit at. Saturation, do you think  anyone who buys this amp can actually measure  and drive this amp  below the saturation point? I dont think so. Its nice for you and me with test equipment. The only piece of test equipment that most hams have is a SWR/wattmeter, especially those who buy a CB amp! You being way too optimistic about ham skill levels.

Here is a link and review of this amplifier. It even mentions your callsign in the review of this amp. Even here you recommend 300 to 400 watts not 200 watts of output.

http://pa0fri.home.xs4all.nl/Lineairs/HLA300/hla300eng.htm

Again here you can see how users want to use their favorite little amp not at 200 watts but at 300 to 400 watts of output power. When these amps are driven as per this review the splatter is  horrendous just like
you hear on the CB band. You can also get an excited idiotic  mobile ham who thinks that cranking up the mic gain a bit helps, and   by golly the band is awash with crud. I hear these Turkeys every day doing this.

The typical ham who buys  this kind of amp is not considered and measured like  yourself. They will not even consider, supply voltage, saturation, ALC overshoot etc etc. They will drive the amp and look at the wattmeter, smile and say all is well. This is unfortunately how most users of these amps operate. They dont check to see if the amp is saturating. They dont use a second receiver or SDR to actually check the quality of their signals etc etc. The end result
is  that other users have to put up with the splatter collateral damage because of ignorance.

This kind of splatter does not happen if they use was using an Ameritron AL811, FL2100Z or any other good tube amplifier. When there are so many good cheap ham amps available that dont cause such high levels of splatter why even bother to use this CB junk? There are so many hams who cant even tell if a signal is dirty or splattering, or simply dont want to offend their QSO partners. While there are a few hams who stick their necks out and inform stations that they are splattering most hams dont bother these days because of the attacks that they suffer from offending stations, Attacks about your poor receiver, your ears, your NB, your wife, you a idiot etc etc.

 If I got a splatter report on my signal. I simply ask the reporting station what my signal strength was on their receiver, their radio brand/model and thank them for the report. I would then go off air connect my SDR or second good receiver and check my signal. This  what most hams should do rather than acting tough because they ignorant, dont want to know or like acting like the tough big mouth on the air. New hams especially those from the CB band seem to have a Pitt bull attitude on the ham bands, that is that their attitude is to destroy or humiliate any ham who criticizes  their operating practices. In this climate its difficult trying
to help stations reduce mic gain or drive for a clean signal. I would  gladly recommend any piece of commercial equipment if hams  had a better attitude and  a technical approach towards using this equipment. If  hams who use this equipment cant understand what splatter and IMD is,  and then want to  launch  personal attack   because of their ignorance then the best bet is for most hams to not use this kind of equipment.

 My view is  ham radio is no longer a technical fraternity  that fosters and cares for fellow amateurs, its  just become of hobby of selfish people buying equipment and selfishly doing whatever they want  with very little regard of how they are behaving.  I get this argument  time and time again I spend 10,000 dollar on  brand X and I dont splatter. I would have  preferred to hear I spent 10,000 dollars on a spectrum analyzer and I see no splatter or IMD. The ignorance around the use of CB amplifiers is indication of the poor standards that have infiltrated  the ham service from the CB band.

 I am not against  CB'ers or new hams. I know many CB'ers who have become great hams. However when people use ignorance and poor technical skills as a defense argument  and that they think that they have every  right to use  operating practices that causes harm to other users of the band this  I dont agree with. This includes criticizing selecting equipment that is poor like CB amps.

Hams should have the right  to criticize any ham who operates a CB solid state amp or any amp for that matter like they do on the CB bands by driving the crap out of the unit and taking out 20khz. Unfortunately their many CB hams who think that obtaining a ham licenses gives them the right to tell old hams how they did it on the CB band and that  they are expert radio operators  with 30 years experience  on radio. If I had 1 years of radio experience  I would expect that I can operate my station in a clean manner.  What good is 30 years of experience on radio if all you ever learned is how to drive the crap out of equipment and use equipment that has poor technical standards?

In the past  years in ham radio when equipment building was routine, and there was a lot of splatter around like the old AM days, hams expected signal quality reports. Splatter reports were routinely done and nobody took offense
at any ham who criticized or gave a signal quality report that was bad. Hams appreciated splatter reports. The attitude today is  much difference, because  telling a ham that his equipment is splattering means telling a ham that his equipment that he has bought is crap and that he has no idea what he or she is doing. In the case of someone causing splatter, they  dont really know what they are doing this is the sad reality. Even radios with relatively poor IMD performance can be used on the air with  little harm to other users. This is before we even start with operating practices like ESSB which causes excessive splatter regardless of the skill level of the operator. If your signal is not brick wall on a SDR receiver you are splattering  and this splatter is easy to see on any SDR. We have tools  that are readily available unfortunately most hams dont want to acknowledge that technology has moved ahead and that splatter reports are not personal attacks.

I tested the amp  and radio using  several methods.

1. Installed in the car with the amp in the car with second battery. Nominal voltage 13.8 in all cases. Voltage drop was minimal.
2. Installed in the car with the amp on the second battery  and a Voltage boost regulator on the IC706 which maintained the voltage  on the  IC706 at 13.9 volts. I did not have a regulator big enough for the amp.
3. Tested on the work bench with  a 200 amp DC telecommunications  for both the amp and the radio. The figures that I quoted above was on the DC supply not even on the mobile. I am sure that in the mobile
the figures would have been far worst. 
4. I used 2 X R&S  spectrum analyzer one was a real spectrum analyzer one with  a onscreen dynamic range of more than 100db. My main analyzer is a R&S FSU All these analyzers have ITU compliant
pass fail IMD mask software suites. I believe in dynamic IMD measurements not 2 tone figures which are are a static indicative test that  has little relevance to how a ham transmitter works in the real world.

The average ham who installed a mobile radio and a RM italy amp is not going  to go through all the motions of testing for saturation, IMD at various drive levels, IMD versus voltage levels etc etc. Asking hams to do
all this before getting on the air is just never going to happen. We should just accept the fact that  ham radio today is a clas service no different to other HF users who buy and operate radio equipment without technical skills. We
should have  Type acceptance standards that are written into law. These type acceptance standards should define the IMD standard based on the ERP of the ham station just like the ITU and FCC standards require by law for commercial users.  Its just unfortunate that hams dont have the skills nor the equipment to drive a poor piece of equipment like the RM300 within acceptable limits. Thats why I dont agree with recommending  such equipment for the ham service where we have to be vigilant  and considerate of other users of the ham bands.



“When i  measured the HLA300 not  with 2 tones using white noise loading using a IC706 and  HLA300 the IMD was disaster at fully output. The IC706 was putting out between 20 and 25 watts for about 300 to 400 watts across all the bands. Thats  about the manufacturers ratings and where most hams would be running them not at 200 watts. Why would spend money on a 400 watt amplifier and run it at 200 watts?  No normal ham would do this. Its a nice feel good argument for hams who buy this CB splatter garbage  and then run the amp at full power. Everyday on the ham bands we hear these crap boxes spewing out splatter and  occupying 20 khz of bandwidth with splatter  when they drive to the full rated output.”

The HLA-300 uses 4 SD1446 80 watt transistors. Why would you try to get 300-400 watts out of an amplifier that is in compression at 300 watts out?

What was your Amplifier Vcc voltage during the test?

What was the occupied bandwidth from the driving  transceiver?

How did you mesure that bandwidth?

What instrument did you measure the bandwidth with?

I still don’t see any hard numbers.

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N4CR
Member

Posts: 1655




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« Reply #51 on: April 21, 2013, 12:23:01 PM »

Well stated, Zenki. Spot on in every example.
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
WV4I
Member

Posts: 136




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« Reply #52 on: May 12, 2013, 06:48:21 AM »

When i  measured the HLA300 not  with 2 tones using white noise loading using a IC706 and  HLA300 the IMD was disaster at fully output. The IC706 was putting out between 20 and 25 watts for about 300 to 400 watts across all the bands.

First of all, the HLA300 is rated at 12W input max, or -3db attenuator must be switched on. Above 16-17W input this attenuator is automatically switched on. Above that at some point the driver(s) usually fail.

Being designed for low power out radios like the Flex 1500, IC-703, FT-817, all 5W, the HLA-300 will easily achieve rated output with <=5W input. Why use more?

Just trying to follow the discussion here.
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WD5GWY
Member

Posts: 391




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« Reply #53 on: May 12, 2013, 10:00:14 AM »

ZENKI, I'm sorry I missed your last post here. This has to be one of the best,
most thought out, reply's that I have ever read from you. Thank you for your
VERY informative post. I would think that anyone who reads this could not
help but understand your position about this amp and others like it. And your
reasons(well founded) for being so (forcefully) against it.
  I hope that this post will give other hams who are considering using an amp
like the RM Italy HLA-300, reason to reconsider their thoughts before spending
money on one. I agree, that most hams, that buy one would in most cases want
to use it to it's fullest potential(output). With low drive, ( 5 watts or less) it might
not be so bad. BUT, even on the link you posted to, there is a mod to allow the amp
to put out nearly 500 watts with only 5 or so watts of drive. Something that a lot
of people might be tempted to do.
  Again, thank you for this post.
james
WD5GWY
 
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K6UJ
Member

Posts: 305




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« Reply #54 on: June 09, 2013, 10:24:11 AM »

ZENKI   are you a ham ?  If so what is your call sign ?

Bob
K6UJ
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TANAKASAN
Member

Posts: 933




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« Reply #55 on: June 11, 2013, 08:14:43 AM »

Given the level of expertise shown in Zenki's posts I don't care if he's a ham or not. This site needs a lot more people like Zenki and I admire his stance on clean transmitters. As for myself, if I receive a report of spatter I shut down and investigate the problem, I also check my output on a regular basis although this depends on spectrum analyzer time at work.

White noise for IMD testing though, I remain to be convinced. My preferred method is three-tone testing but I know that opinions differ.

Tanakasan
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W5JON
Member

Posts: 161




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« Reply #56 on: June 11, 2013, 11:04:58 AM »

Zenki,

ABOVE YOU SAY:  "They will not even consider, supply voltage, saturation, ALC overshoot etc etc'.


Therefore, on your IC-706, what did you do to prevent the very well documented, full power leading edge spike? It is known when the IC-706 is adjusted down to the 10-50W (or so) needed to drive an amplifier, a several millisecond 100+ watt RF pulse is output on initial key down, this "power spike" is not caught by ALC. This is a major design fault with the ALC circuitry inside the ICOM IC-706 and many other ICOM and other transceivers.

What was your correction for this "spike" while testing the RM amplifier?  What was the IMD data result of this "power spike" before and after any correction while testing the RM amplifier?

John  W5JON
« Last Edit: June 11, 2013, 11:26:16 AM by W5JON » Logged
TANAKASAN
Member

Posts: 933




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« Reply #57 on: June 11, 2013, 11:06:01 PM »

There are two possible solutions to the IC706 ALC overshoot problem:

a) Use an external 1M pot and a 9V battery to provide a variable ALC voltage to the rig, use this as your power control. This overrides the ALC circuit and changes its characteristics

b) Always run the rig at 100% and use a power attenuator on the output to reduce it to the correct drive level.

Tanakasan
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WX7G
Member

Posts: 5920




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« Reply #58 on: June 12, 2013, 06:52:49 AM »

ZENKI   are you a ham ?  If so what is your call sign ?

Bob
K6UJ

ZENKI is not a ham. His name is listed at eham.net as Zenki Shingen which is not in the QRZ database.
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N0YXB
Member

Posts: 303




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« Reply #59 on: June 12, 2013, 09:45:19 AM »

Maybe not, but his arguments have merit.
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Vince
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