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Author Topic: ameritron al-811 problem  (Read 8335 times)
AE2DX
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« on: October 04, 2011, 08:43:52 AM »

I purchased a used al-811 which upon checking found a tube broken so I replaced all three with new, checked over complete set soldered a few poor solder joints otherwise unit looks great now the problem, am only getting the max of 200 watts out with about 25 watts drive, power supply is steady at about 1600 volts on transmit, 1700+ standby,  grid current 150 ma, increasing drive and the output goes down as grid current goes up. Does this on all bands although 80 meters I can get little over 225 + watts out. Antenna tuner works OK with just exciter running full 100 watts from my transmitter. in line the tuner is full power rated tried running amp without tuner in line to a 80 meter loop I have which is flat on 3.60 kHz still only little over 225 watts with about 25 watts drive. have spoken with tech at Ameritron told me to check some things and walked me through on the operation but they cant figure it out. I don't have the ALC plugged in to the rig in fact I unsoldered the circuit from the amp figuring maybe something in circuit causing the problem but works the same. I have tried adjusting the coils on the band switch per the manual from the rear of the unit did originally improve the output by about 10 watts on each band so I am at a dead end right now as to why I can only get 200 watts out. anyone have this problem before or can help me in any way to fix this. I am beginning to wonder if the tubes I bought might be bad. I also am running this on 220volts as the tech at ameritron said  my origanal line voltage 110 might not have enough power as their were other things on line so I had a 220 volt separate line direct into shack did help on light dimming on meters but still only 200 watts.
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W8JI
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« Reply #1 on: October 04, 2011, 09:55:57 AM »

Try using paragraphs to separate thoughts or topics!!!

I purchased a used al-811 which upon checking found a tube broken so I replaced all three with new, checked over complete set soldered a few poor solder joints otherwise unit looks great now the problem, am only getting the max of 200 watts out with about 25 watts drive,

What power meter do you have? That output sounds OK depending on the tuning.

Quote
power supply is steady at about 1600 volts on transmit, 1700+ standby,
 

That indicates the power line is probably OK.

Quote
grid current 150 ma, increasing drive and the output goes down as grid current goes up. Does this on all bands although 80 meters I can get little over 225 + watts out.


None of that makes any sense. Grid current cannot go down as drive power goes up. Do you mean you are changing the load control? Did you read and follow the manual for tuning?

Quote
Antenna tuner works OK with just exciter running full 100 watts from my transmitter. in line the tuner is full power rated tried running amp without tuner in line to a 80 meter loop I have which is flat on 3.60 kHz still only little over 225 watts with about 25 watts drive.

OK

Quote
have spoken with tech at Ameritron told me to check some things and walked me through on the operation but they cant figure it out. I don't have the ALC plugged in to the rig in fact I unsoldered the circuit from the amp figuring maybe something in circuit causing the problem but works the same.


Why would you "unsolder the ALC"Huh? That clearly shows you are doing things you should not be doing. Once the ALC is unplugged, it is unplugged and has NO effect. Unsoldering is foolish.

Quote
I have tried adjusting the coils on the band switch per the manual from the rear of the unit did originally improve the output by about 10 watts on each band so I am at a dead end right now as to why I can only get 200 watts out. anyone have this problem before or can help me in any way to fix this.


You are on your way to ruining the amplifier, and maybe hurting yourself in the process. Why would you adjust the coils for no reason??? You unsoldered the ALC for no reason, and you are adjusting coils for what reason??


Quote
I am beginning to wonder if the tubes I bought might be bad. I also am running this on 220volts as the tech at ameritron said  my origanal line voltage 110 might not have enough power as their were other things on line so I had a 220 volt separate line direct into shack did help on light dimming on meters but still only 200 watts.


Since you said HV only drop 100 volts at 200 watts out, the power line is good. There is no reason to guess.

I'm thinking you need to get someone over to help you, and keep your hands out of the equipment until you get more experienced help. There was no reason for you to unsolder the ALC inside the amp, probably no reason to run a 240 volt line, and no reason to adjust the input slugs.   

If you keep going the way you are going you will either ruin the amplifier or hurt yourself.

73 Tom
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CBISBACK
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Posts: 37




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« Reply #2 on: October 04, 2011, 10:37:35 AM »

What kind of dummy load are you using?

Are you "really" an Extra Class ham?

Your trouble shooting techniques would indicate you don't know what you're doing.

You better send this amp back to Ameritron before you kill yourself.

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AE2DX
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Posts: 5




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« Reply #3 on: October 04, 2011, 01:09:56 PM »

Tom, Yes I am a Extra class, I have been a electronic tech working on home entertainment equipment for RCA and Sears comp.for over 40 years as for the tuning of the coils this was suggested by the Ameritron techs having gone over all I have stated here on this site. I am quite capeable of working on this unit but have reached a dead end to go any further I was hopping to maybe find someone else who might have had this problem  that I am overlooking. Ameritron themselves were also stumpted but didn't want me to ship it to them because they feel I have gone through all the suggestions  they stated and between the 2 or 3 tech working there all agreed. As for the power meter its on the Antenna tuner I have which is a Yaesu model Fc-102 and works fine with the Transmitter I am using which is a Icom IC 729 the meter is very accurate on all three scales 0-20watts-0-200watts and 0-1200 watts as I also stated My 80 meter loop is almost flat at 3.60MHz and running the amp without the tuner in line and having the same results I have eliminated the Ant tuner. I am not going to ruin my amp or put myself in harms way trying to find the problem. Like I said I was grasping at straws by disconnecting the ALC circuit from the amp which was reconnected to satisfy myself that its not the circuit causing the problem and it wasn't. Their is no arcing marks on any of the switches or tuning caps the amp tunes like the instructions state but can only get out 200 watts When I adjust the drive the grid current does go up but the power goes down that's what I am trying to figure why. I don't need to be ridiculed for what I am trying to do. I am not familiar with working on power amplifiers as this is my first but am quite capable of troubleshooting but this problem has me and others I have spoken with stumpted as to what is happening
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W8JI
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« Reply #4 on: October 04, 2011, 01:49:19 PM »


Quote
Tom, Yes I am a Extra class, I have been a electronic tech working on home entertainment equipment for RCA and Sears comp.for over 40 years

 I never asked if you were an extra. Who cares? Class of license has nothing to do with technical ability or basic knowledge.

Quote
as for the tuning of the coils this was suggested by the Ameritron techs having gone over all I have stated here on this site. I am quite capeable of working on this unit but have reached a dead end to go any further I was hopping to maybe find someone else who might have had this problem  that I am overlooking. Like I said I was grasping at straws by disconnecting the ALC circuit from the amp which was reconnected to satisfy myself that its not the circuit causing the problem and it wasn't

There was never a reason for you to unsolder the ALC system. Once ALC is unplugged, it is off.

There was never a reason to change to 240 because you can't get over 200 watts. Only change voltage if when driving the amp you see excessive plate voltage loss.

There was never a reason to adjust the input slugs unless input SWR was high. You do NOT peak input slugs for maximum power, especially when you can only get 200 watts.


Quote
   Ameritron themselves were also stumpted but didn't want me to ship it to them because they feel I have gone through all the suggestions  they stated and between the 2 or 3 tech working there all agreed.


I have no idea what you told them, but what you are saying here can't help anyone help you. You have to stop, and answer some questions one at a time.

When you say you advance drive, does the power in the radio go up? You are saying grid current goes up but power output goes DOWN?

This is the drive control on the radio, is that correct?

What is the plate current and how does it change?

Where did you get the tubes?

How much power does your radio run into the tuner when the tuner is on the 1.2 kW meter scale?

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WX7G
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« Reply #5 on: October 04, 2011, 02:29:55 PM »

To see if the problem is caused by the new tubes: Remove them and install the two left over old tubes. Run the amp and if it puts out 400 watts with 50 watts of drive the new tubes are the culpret.
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KA5N
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Posts: 4380




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« Reply #6 on: October 04, 2011, 03:41:11 PM »

Have you checked the input SWR on your amplifier?  If it is too high, when you advance drive your transceiver will automatically cut back on its output power.  So when you increase the
drive you may actually decrease it (depending on how the tranceiver operates internally).

Unless you monitor your amps input swr, and work into a good 50 Ohm load (preferably a
dummy load) you may just chase your tail.
Allen
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AE2DX
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Posts: 5




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« Reply #7 on: October 04, 2011, 05:03:43 PM »

To see if the problem is caused by the new tubes: Remove them and install the two left over old tubes. Run the amp and if it puts out 400 watts with 50 watts of drive the new tubes are the culpret.


Thank you for the information I was going to try that but not knowing that much about amps I didn't want to maybe cause more problems , but I have the old tubes and will try it tomorrow many thanks for the fast responce to my inquiry.

Fred
AE2DX
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AE2DX
Member

Posts: 5




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« Reply #8 on: October 04, 2011, 05:10:20 PM »

Have you checked the input SWR on your amplifier?  If it is too high, when you advance drive your transceiver will automatically cut back on its output power.  So when you increase the
drive you may actually decrease it (depending on how the tranceiver operates internally).

Unless you monitor your amps input swr, and work into a good 50 Ohm load (preferably a
dummy load) you may just chase your tail.
Allen


the meter on the driver does advance to 50 watts with no problem to the amp because of the problem I am having I havent gone over 30 watts till I find the reason thanks for the responce will be trying the old tubes which I received with the set but one was broken in transit but will try using only the 2 left. Thank you for your fast responce.
Fred
AE2DX

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W8JI
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« Reply #9 on: October 04, 2011, 07:22:02 PM »

Have you checked the input SWR on your amplifier?  If it is too high, when you advance drive your transceiver will automatically cut back on its output power.  So when you increase the
drive you may actually decrease it (depending on how the tranceiver operates internally).

Unless you monitor your amps input swr, and work into a good 50 Ohm load (preferably a
dummy load) you may just chase your tail.
Allen

the meter on the driver does advance to 50 watts with no problem to the amp because of the problem I am having I havent gone over 30 watts till I find the reason thanks for the responce will be trying the old tubes which I received with the set but one was broken in transit but will try using only the 2 left. Thank you for your fast responce.
Fred
AE2DX

This will get even more confusing with everyone stirring the soup.

Fred never has answered any important questions, like

When you say you advance drive, does the power in the radio go up? You are saying grid current goes up but power output goes DOWN?

This is the drive control on the radio, is that correct?

What is the plate current and how does it change?

Where did you get the tubes?

How much power does your radio run into the tuner when the tuner is on the 1.2 kW meter scale?
 
73 Tom

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K0ZN
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Posts: 1544




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« Reply #10 on: October 04, 2011, 08:17:14 PM »

To AE2DX:

I read your comments and thought I would give you some "hard numbers" as I have an AL-811.  This is what I see on my AL-811:
Power readings are accurate, confirmed by TWO power meters.

3.600 Khz:  560 Watts output.  Drive is 50 watts input.  Ip is 470 ma.  Ig is 125 ma.  Load control = 6.4   Plate control = 4.1

7.150 Khz:  540 Watts output.  Drive is 38 watts input.  Ip is 380 ma.  Ig is 90 ma.    Load control = 5.0   Plate control = 7.4

14.200 Khz: 550 Watts output.  Drive is 42 watts input.  Ip is 470 ma.  Ig is 110 ma.  Load control = 3.0   Plate control = 8.7

Note that the above are just "tune up" numbers. i.e. the amp is "key down" for just a FEW SECONDS to obtain correct tuning and
these RF output numbers. DO NOT operate any continuous carrier or CW modes at these power levels!!! DO NOT hold the amp
"key down" at these power levels for more than a few seconds at a time and allow a cool off period between tuning. READ THE
OWNER's MANUAL ! These would be SSB settings only.  I operate mostly CW and use moderately reduced output to keep the
tubes within ICAS ratings.

I just wanted to pass these numbers on to you for a reference.  Your results probably WILL vary somewhat from these.

In the not too recent past, I have had several problems with the tubes. This amp is about two years old and I have gone through
6 tubes to get three (what I hope are good ones). Previous tube failures were: one catastrophic short, and two went gaseous. One of
the gaseous tubes also developed a hole in the plate. Q.C. of the Chinese tubes varies HUGELY from what I can see. I have had best luck
with "Taylor" tubes from RF Parts. They also give a decent warranty.

Based on what I read in your comments, I would spend the money to buy a matched set of FOUR tubes. Matching is a controversial
subject, but I think in this case they actually test them in *some* fashion, which at least weeds out some initial failures.  My experiences
with RF Parts has been quite good. The reason to buy four 811A tubes is because the reality is that you stand a pretty high chance of
having one tube go bad...... that is just reality. FYI gassy tubes will develop and irridescent glow, typically.

TAKE W8JI's advise !!   That said, DO go through it and look for poor solder joints and loose screws and nuts. Check EVERY fastener for tightness.

For what it is worth, I do not use the ALC, but I also don't over drive it and understand tube amplifier operation. My AL-811 is also set up for
240 V operation. I typically see about 1,900 volts (per meter on amp) under NO LOAD conditions.  I have a stiff 240 V line, so there is not much drop
in the plate voltage at Key Down.

The only INPUT circuit tuning slugs I re-tuned were the 30/20 and 17/15 slugs to obtain 1:1 on 20 and 17 M. I do not use the amp on 30 M....no
point with the power limit on that band. I found the input SWR unacceptable on both 17 and 15, so I elected to "move" the amp to 17 and
"delete" 15 M. From what I could see, you cannot have acceptable SWR on both bands....so I chose 17 M.

As W8JI said: you do NOT tune the input circuit for max. output.....it is just a MATCHING network between the 50 ohm coax from the rig and the input
impedance of the tubes. If you "must" tune the input circuits, tune it/them for lowest SWR/best match on the band/bands desired.

You MUST have an accurate RF power meter to tune up/load this amplifier correctly.

I had some initial "infant mortality failures" with my AL-811, but once those were sorted out/fixed, it has been very reliable, easy to tune and stable.

When operated PROPERLY and not abused, the AL-811 is a pretty neat little box for what it is. From the threads I have read on here (eHam) I
suspect a lot of the problems with this amplifier are USER induced ! The 811A tubes are a weak link, but improper and abusive tuning techniques are
very hard on them too.

Good Luck.....

73,  K0ZN
« Last Edit: October 04, 2011, 08:28:00 PM by K0ZN » Logged
AE2DX
Member

Posts: 5




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« Reply #11 on: October 05, 2011, 06:04:20 AM »

To AE2DX:

I read your comments and thought I would give you some "hard numbers" as I have an AL-811.  This is what I see on my AL-811:
Power readings are accurate, confirmed by TWO power meters.

3.600 Khz:  560 Watts output.  Drive is 50 watts input.  Ip is 470 ma.  Ig is 125 ma.  Load control = 6.4   Plate control = 4.1

7.150 Khz:  540 Watts output.  Drive is 38 watts input.  Ip is 380 ma.  Ig is 90 ma.    Load control = 5.0   Plate control = 7.4

14.200 Khz: 550 Watts output.  Drive is 42 watts input.  Ip is 470 ma.  Ig is 110 ma.  Load control = 3.0   Plate control = 8.7

Note that the above are just "tune up" numbers. i.e. the amp is "key down" for just a FEW SECONDS to obtain correct tuning and
these RF output numbers. DO NOT operate any continuous carrier or CW modes at these power levels!!! DO NOT hold the amp
"key down" at these power levels for more than a few seconds at a time and allow a cool off period between tuning. READ THE
OWNER's MANUAL ! These would be SSB settings only.  I operate mostly CW and use moderately reduced output to keep the
tubes within ICAS ratings.

I just wanted to pass these numbers on to you for a reference.  Your results probably WILL vary somewhat from these.

In the not too recent past, I have had several problems with the tubes. This amp is about two years old and I have gone through
6 tubes to get three (what I hope are good ones). Previous tube failures were: one catastrophic short, and two went gaseous. One of
the gaseous tubes also developed a hole in the plate. Q.C. of the Chinese tubes varies HUGELY from what I can see. I have had best luck
with "Taylor" tubes from RF Parts. They also give a decent warranty.

Based on what I read in your comments, I would spend the money to buy a matched set of FOUR tubes. Matching is a controversial
subject, but I think in this case they actually test them in *some* fashion, which at least weeds out some initial failures.  My experiences
with RF Parts has been quite good. The reason to buy four 811A tubes is because the reality is that you stand a pretty high chance of
having one tube go bad...... that is just reality. FYI gassy tubes will develop and irridescent glow, typically.

TAKE W8JI's advise !!   That said, DO go through it and look for poor solder joints and loose screws and nuts. Check EVERY fastener for tightness.

For what it is worth, I do not use the ALC, but I also don't over drive it and understand tube amplifier operation. My AL-811 is also set up for
240 V operation. I typically see about 1,900 volts (per meter on amp) under NO LOAD conditions.  I have a stiff 240 V line, so there is not much drop
in the plate voltage at Key Down.

The only INPUT circuit tuning slugs I re-tuned were the 30/20 and 17/15 slugs to obtain 1:1 on 20 and 17 M. I do not use the amp on 30 M....no
point with the power limit on that band. I found the input SWR unacceptable on both 17 and 15, so I elected to "move" the amp to 17 and
"delete" 15 M. From what I could see, you cannot have acceptable SWR on both bands....so I chose 17 M.

As W8JI said: you do NOT tune the input circuit for max. output.....it is just a MATCHING network between the 50 ohm coax from the rig and the input
impedance of the tubes. If you "must" tune the input circuits, tune it/them for lowest SWR/best match on the band/bands desired.

You MUST have an accurate RF power meter to tune up/load this amplifier correctly.

I had some initial "infant mortality failures" with my AL-811, but once those were sorted out/fixed, it has been very reliable, easy to tune and stable.

When operated PROPERLY and not abused, the AL-811 is a pretty neat little box for what it is. From the threads I have read on here (eHam) I
suspect a lot of the problems with this amplifier are USER induced ! The 811A tubes are a weak link, but improper and abusive tuning techniques are
very hard on them too.

Good Luck.....

73,  K0ZN


k0zn thank you very much for the information, the tubes were bought through Ameritron but they arrived in a MFJ box the tubes were in a plain white box with CHina stamped on top I will keep your chart for referance and do appreaciate the help in this matter I have been checking out other tubes and Taylor seems to be a good choice according to others so I will most likely go that route thanks agaain best 73
Fred AE2DX
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K0ZN
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« Reply #12 on: October 05, 2011, 12:07:51 PM »

 AE2DX:

I'm glad that info was of some help.  This comment won't win me any friends, but from all I can see and have heard, your experiences are not horribly unusual.
I had some issues with my AL-811, but once past them, it has been a good little amp. You have to understand that that amplifier is built to a price point....it is not and Alpha and you did not pay Alpha prices. "It is what it is."....but that does not mean it can't or won't be a good, reliable amp with proper care and TLC. It is also easy and cheap to repair if you have to.

Go to W8JI.com and carefully read the comments about amplifier tuning. WELL worth your time.

One other last caution, if you are not intimately familiar with tube type amplifiers; Keep a small mirror in the shack !!  You NEED to periodically look in the amp at the tubes
(during a transmission now and then) to make sure the color of the tube plates is acceptable. Typically, on SSB you won't see much if any color on the tube plates....maybe a tiny bit of very dull red....that is OK. On CW or data modes you MUST reduce the power output to keep the tubes within their heat dissipation ratings. On CW, typically,
with about 325 watts output, I can see a dull red to slight dull orange glow over PART of the plate....that is also "OK".  BRIGHT orange, or even a lighter color is NOT OK and you are on the way to damaging the tubes. If you operate CW, the best way I have found to minimize plate heating is to tune and load the amp to about 375 watts output, then REDUCE the drive to give about 325 watts output. I don't operate data modes, but they would require even lower output as the tubes would be operating closer to CCS ratings than ICAS. Too many people try to squeeze the last watt out of their amps and it is absolutely pointless...if you run an amp at 10% reduced power output, NOBODY listening to your signal can tell the difference on their S-meter, but your tubes will last longer and be happier. The best way to operate that amp on SSB is to load it to full power output...or just SLIGHTLY less....(i.e. the point where increased drive does not result in more power out), then REDUCE the drive about 5 to 10%. This keeps your signal clean and the tubes happy. Over driving an amp is one of the worst things you can do: it can distort your signal...making it HARDER for the other station
to hear you clearly and it creates splatter on either side of you signal. (I look at splatter as guys "advertising" that they DON'T know much about amplifiers or how to tune them!)

Again...good luck.

73,  K0ZN
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N4ATS
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« Reply #13 on: October 05, 2011, 12:12:41 PM »

Per a previous thread I responded to.. I actually seen a few that this symptom came up on and this fixed it...

Replace D-16 (in some cases marked other) (right behind the meters) located on the step board. I wrote a thread about it and many said they fixed theirs as well. Its a typical flaw in design. It will be shorted.
« Last Edit: October 05, 2011, 12:14:23 PM by N4ATS » Logged
W8JI
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Posts: 9304


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« Reply #14 on: October 05, 2011, 12:41:43 PM »

Per a previous thread I responded to.. I actually seen a few that this symptom came up on and this fixed it...

Replace D-16 (in some cases marked other) (right behind the meters) located on the step board. I wrote a thread about it and many said they fixed theirs as well. Its a typical flaw in design. It will be shorted.


The diode protects the meters.

The only time the diode blows is when a tube shorts.

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