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Author Topic: What Changes Would You Do To Your Ameritron 811/811H?  (Read 28239 times)
MM0IMC
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Posts: 218




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« on: April 05, 2015, 09:54:22 AM »

If you could make changes to improve your Ameritron 811 or 811H, what would it be? Huh

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K7MH
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Posts: 455




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« Reply #1 on: April 05, 2015, 10:14:56 AM »

What I did was SELL my AL-811 and buy an AL-80B!!

Actually I was the third owner of the AL-811 and never had any problems with it other than replacing the power switch once. I had it for several years.
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N9AOP
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Posts: 1119




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« Reply #2 on: April 05, 2015, 10:31:14 AM »

I sold mine and bought a KPA500.
Art
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KQ6PJ
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Posts: 15




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« Reply #3 on: April 05, 2015, 11:17:14 AM »

What I did was SELL my AL-811 and buy an AL-80B!!



What's not good about the 811?
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W1QJ
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Posts: 2893




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« Reply #4 on: April 05, 2015, 12:01:25 PM »

What I did was SELL my AL-811 and buy an AL-80B!!



What's not good about the 811?

The tubes that are avaiable
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KM1H
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Posts: 4722




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« Reply #5 on: April 05, 2015, 02:15:28 PM »

Plus the quality control and on the fly fixes at the factory; its all hit or miss.
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KK5DR
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« Reply #6 on: April 05, 2015, 04:08:13 PM »

Ask anyone that owns a Collins 30L-1. A set of four is only good for a reliable 500 watts out, running with 1500 volts on the plate.
The Ameritron runs them at 1800, and claims far too much power out of them. Not reliable in those conditions.
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N4ATS
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Posts: 1274




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« Reply #7 on: April 05, 2015, 04:22:43 PM »

"If you could make changes to improve your Ameritron 811 or 811H, what would it be? "

Dump it , get an FL-7000
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AD4U
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Posts: 2536




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« Reply #8 on: April 05, 2015, 05:40:30 PM »

Ditto on the AL-80B. With a single 3-500 and only a muffin type fan blowing across the tube, it is a GREAT 750 watt amp.  IMO it is a very over rated 1000 watt amp. Yes it will "do" 1000 watts but only by driving the single 3-500 way past its design parameters.

Dick AD4U
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W8JX
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Posts: 13268




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« Reply #9 on: April 05, 2015, 06:10:00 PM »

If you could make changes to improve your Ameritron 811 or 811H, what would it be? Huh



As others have said, SELL IT and get a real amp. It is a over rated design that requires you exceed tubes rating to make rated output and it is possible to melt/damage tubes in mere seconds on tune-up because of limitation of design of 811's. A used AL80 is thrice the amp a new AL811 is. (the single 3-500z in a AL80 has 3x the rated plate dissipation of all 3 tubes combined in a AL811) Generally speaking you want to have at least a rated dissipation equal to 1/2 half rated power output for a reliable amp that will not have a melt down during tune up and operation as finals have to dissipate at least 1/3 of input power (ie for 800 watts out you have at least 400 watts being dissipated key down  A AL811 has about one half of needed dissipation at its "rated" output.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
N3QE
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Posts: 5559




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« Reply #10 on: April 06, 2015, 06:14:50 AM »

The 811H is already the most refined 811A-based amp ever. But to deal with arc-over faults of Chinese tubes the past couple years, make sure it has W8JI's suggested mods (these may be present in recently manufactured units already): http://www.w8ji.com/al811_important_modifications_changes.htm

Keep a bag of spare fuses and diodes. Almost certainly in an arc-over, D16 on the metering board will fail shorted to save the meters.
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W8JX
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Posts: 13268




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« Reply #11 on: April 06, 2015, 06:23:16 AM »

The 811H is already the most refined 811A-based amp ever. But to deal with arc-over faults of Chinese tubes the past couple years, make sure it has W8JI's suggested mods (these may be present in recently manufactured units already): http://www.w8ji.com/al811_important_modifications_changes.htm

Keep a bag of spare fuses and diodes. Almost certainly in an arc-over, D16 on the metering board will fail shorted to save the meters.

I would not use the word "refined" here as it implies a quality item when it is not. Any way you cut it, it is a marginal amp that is easy to toast it's tubes tuning because of its marginal design. If you run it at about 75% or less of its rated output you will get longer life from tubes. Some use 572's but since amp lacks power to properly heat plates to getter tubes they could have a shorter life than 811's.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
MM0IMC
Member

Posts: 218




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« Reply #12 on: April 06, 2015, 08:03:30 AM »

I've been eyeing up the AL-80B, but not sure of the quality given my previous dealings with Ameritron/MFJ.  Does it work okay on 10m/12m with a low input SWR and it stable?  I want something that could run 400W PEP all day without issues on those bands.

My other option was to trade the 811H in against an Alpin 100, which seems to be far more reliable and can be used on 6m as well (a bonus).
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KF7CG
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Posts: 1212




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« Reply #13 on: April 06, 2015, 09:46:00 AM »

I personally have found no problems with my AL-811H.

It works well on 10-12 meters and all the other band segments it covers. Is it fancy, sexy, most modern; no it just works.

Tuning, no problem; I came up with sweep tube rigs that required the same care when tuning the transceiver. Remember, dummy loads are marginal during long tuning sessions. It won't take your amp to long to toast a cantenna if care isn't used and the dry ones die faster.

I will admit one problem with my AL-811H, the set screws on the loading capacitor had vibrated loose in shipment. I fixed those at the same time I activated the Aux (10-12 meter) bandswitch position.

Would have to run 240 VAC to the shack if I were to go anything higher, so I will stay with what I have. it works.

KF7CG
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W5WSS
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Posts: 2283




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« Reply #14 on: April 06, 2015, 09:47:03 AM »

The changes that Tom Rauch W8JI The Design Engineer recommends. They can be found at W8JI.com

73
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