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Author Topic: Ameritron AL-811 'fixes'  (Read 17564 times)
N8FVJ
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Posts: 900




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« Reply #75 on: January 19, 2018, 03:47:30 PM »



Quote
Amp applies approximately 1.3 amps ripple current at capacitors with 700ma dead key load. PS without any C applied is zero ripple current.

How did you derive that 1.3A?

Carl
[/quote]

Power supply software simulator.
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KM1H
Member

Posts: 5511




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« Reply #76 on: January 19, 2018, 06:04:31 PM »

Which one?
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N8FVJ
Member

Posts: 900




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« Reply #77 on: January 19, 2018, 06:16:01 PM »

PSU Designer II. Download here-   http://www.duncanamps.com/psud2/download.html
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N1RND
Member

Posts: 57




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« Reply #78 on: January 25, 2018, 04:59:01 AM »

How about a quieter fan. 
I have a Papst 8800N on the way.   From what I gather is this was fan first used in these amps and was quieter.   The Mechatronis one they use now is considerably cheaper price wise.
I will post my results.

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W8JX
Member

Posts: 13268




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« Reply #79 on: January 25, 2018, 05:05:39 AM »

How about a quieter fan. 
I have a Papst 8800N on the way.   From what I gather is this was fan first used in these amps and was quieter.   The Mechatronis one they use now is considerably cheaper price wise.
I will post my results.

Not sure what fascination is with need for quieter fans. On a amp, if you cannot hear it it as most likely not moving enough air. Lower RPM whisper fans tolerate less back pressure and reduce flow with slightest restriction vs a higher RPM fan.
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
N8FVJ
Member

Posts: 900




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« Reply #80 on: January 25, 2018, 05:43:49 AM »

Fan is not noisy in the AL-811 amplifier. You hear it in the background is all.
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K4RVN
Member

Posts: 261




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« Reply #81 on: January 25, 2018, 12:52:25 PM »

To all those who get a feeling to look the other way on an AL811 amp with 811A tubes, I owned one three years no problems and used it almost daily. A great entry level amp, simple and not costly. So many appear to want to pay little and expect much. The AL 811 has an oversize power supply, same as used in the H model with four tubes. Most are bought by new hams operating their first amp who abuse the tuning process thus the blown tube and bad amp reputation. That's my opinion as a previous owner who ran about 500 watts SSB only, no CW etc. As others have said I subscribe that an AL 80B is a much better amp for the money.

Frank
  
« Last Edit: January 25, 2018, 12:55:10 PM by K4RVN » Logged
N1RND
Member

Posts: 57




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« Reply #82 on: January 25, 2018, 04:06:01 PM »

How about a quieter fan. 
I have a Papst 8800N on the way.   From what I gather is this was fan first used in these amps and was quieter.   The Mechatronis one they use now is considerably cheaper price wise.
I will post my results.

Not sure what fascination is with need for quieter fans. On a amp, if you cannot hear it it as most likely not moving enough air. Lower RPM whisper fans tolerate less back pressure and reduce flow with slightest restriction vs a higher RPM fan.
I'm not expecting it to become "silent" but it can be heard from the shack all the way down the hall into the kitchen.
OEM Mechatronics fan specs.  3000 rpm, 29 cfm, 36 db.
        Papst 8800n fan  specs.  2500 rpm, 27.7cfm, 28db.
Even if it is only a little quieter I'll be satisfied.
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N8FVJ
Member

Posts: 900




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« Reply #83 on: January 25, 2018, 04:24:00 PM »

How about a quieter fan. 
I have a Papst 8800N on the way.   From what I gather is this was fan first used in these amps and was quieter.   The Mechatronis one they use now is considerably cheaper price wise.
I will post my results.

Not sure what fascination is with need for quieter fans. On a amp, if you cannot hear it it as most likely not moving enough air. Lower RPM whisper fans tolerate less back pressure and reduce flow with slightest restriction vs a higher RPM fan.
I'm not expecting it to become "silent" but it can be heard from the shack all the way down the hall into the kitchen.
OEM Mechatronics fan specs.  3000 rpm, 29 cfm, 36 db.
        Papst 8800n fan  specs.  2500 rpm, 27.7cfm, 28db.
Even if it is only a little quieter I'll be satisfied.

My fan is rather quiet. I could not hear it out of the radio shack in hallway.
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W8JX
Member

Posts: 13268




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« Reply #84 on: January 25, 2018, 04:28:33 PM »

How about a quieter fan.  
I have a Papst 8800N on the way.   From what I gather is this was fan first used in these amps and was quieter.   The Mechatronis one they use now is considerably cheaper price wise.
I will post my results.

Not sure what fascination is with need for quieter fans. On a amp, if you cannot hear it it as most likely not moving enough air. Lower RPM whisper fans tolerate less back pressure and reduce flow with slightest restriction vs a higher RPM fan.
I'm not expecting it to become "silent" but it can be heard from the shack all the way down the hall into the kitchen.
OEM Mechatronics fan specs.  3000 rpm, 29 cfm, 36 db.
        Papst 8800n fan  specs.  2500 rpm, 27.7cfm, 28db.
Even if it is only a little quieter I'll be satisfied.

You cannot hear 36 db all the way down the hall. If you do it has a bad bearing. Also on CFM  rating that is with no back pressure and a lower RPM fan flow decreases quicker with back pressure than a higher RPM one so flow difference will be greater than you think. You should never decrease airflow on a amp, any amp.
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
K4RVN
Member

Posts: 261




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« Reply #85 on: January 26, 2018, 09:09:42 AM »

That's good advice from JX as the middle tube runs quite hot on the AL 811. The little fan on the back is a smaller diameter thus runs at a higher RPM than some Ameritrons to provide the cooling. My AL 80A and B were much quieter. My AL 800H with its' blower is much louder. I use headphones for less noise so the fans don't bother me now. You can use an infrared thermometer from Harbor freight to check the existing temperature with the amp in use, then with another fan if you decide to go that route. The thermometers can be bought for around 20 bucks.
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W8JX
Member

Posts: 13268




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« Reply #86 on: January 26, 2018, 10:12:15 AM »

That's good advice from JX as the middle tube runs quite hot on the AL 811. The little fan on the back is a smaller diameter thus runs at a higher RPM than some Ameritrons to provide the cooling. My AL 80A and B were much quieter. My AL 800H with its' blower is much louder. I use headphones for less noise so the fans don't bother me now. You can use an infrared thermometer from Harbor freight to check the existing temperature with the amp in use, then with another fan if you decide to go that route. The thermometers can be bought for around 20 bucks.

My Dentron Cliperton QRO is very loud and moves a lot of air. I placed it on a shelve 30 inches above bench and I have a cloth towel between it and wall so sound from fan does not reflect back off wall. Those two things reduced noise to point nobody has ever mentions fan noise during a QSO.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
KM1H
Member

Posts: 5511




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« Reply #87 on: January 26, 2018, 11:29:24 AM »

I replaced my Clipperton L original fan with an EBM Papst 4600X when I updated it and started using it mostly for AM.
All metal and very tight tolerance German engineering. No complaints of noise even with just the carrier plus I most always wear headphones, a habit since 1955.

No problem running 1200W PEP after a bias change and just slight color on the well gettered Chinese 572B's on voice peaks.

Carl
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W8JX
Member

Posts: 13268




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« Reply #88 on: January 26, 2018, 11:45:15 AM »

I replaced my Clipperton L original fan with an EBM Papst 4600X when I updated it and started using it mostly for AM.
All metal and very tight tolerance German engineering. No complaints of noise even with just the carrier plus I most always wear headphones, a habit since 1955.

No problem running 1200W PEP after a bias change and just slight color on the well gettered Chinese 572B's on voice peaks.

Carl

I reversed flow to suck air out and also rotated top cover 180 degrees some vent holes are in front not back and front panel never gets warm even after many hours. Tubes never get beyond a dull red at 1000+ watts.
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
KB4MNG
Member

Posts: 354




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« Reply #89 on: January 26, 2018, 05:20:12 PM »

The AL-811 at 700 watts PEP output does not tax the transformer in the least.

You are being a bit to generous here. That transformer is not that stout.

He's being very generous regarding his total position. Dumping money in a bad thing. Get an al-80b and forget it. i see them used for about $800. Take care of the tube and will last a lifetime. Mine is still going strong, original to the al 80a built in the mid 80s.

When quality 811s were abundant, it was a marginal viable amp, not the case anymore not matter what you mod.
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