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Author Topic: AL80A vs. AL80B Differences.  (Read 2756 times)
5R8GQ
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Posts: 203




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« on: November 29, 2008, 08:40:21 AM »

Greetings to all the amp experts!

I own an AL80A, which I purchased new from AES many years ago. I love this amp and it has always served me
exceedingly well and has travelled around the globe with me in a Pelican 1620 case. I am a RTTY contester, so I do put it through a lot of %100 duty cycle
use. It came with an Eimac tube, which still works, but started to get soft after about 15 years, so I replaced it with an Amperex 3-500ZG.
( I still travel with the Eimac as a spare!)

Aside from the larger cabinet, dimensions, weight, different meters, inrush current limiting, and the bias that, according to ad copy "completely turns off the 3-500ZG tube between words", what are the other differences between these two amps?

Does the AL80A use the same PS as the two tube 3-500z amp? Was the fact that they needed a smaller PS (for only one 3-500z and less expensive cabinet & chassis) the reason they came out with the "B" model?

Seeing how well the amp has served me, do you think I really need one of the "Step Start Inrush Protectors"?
I don't see the need, but will defer to those more knowledgeable than myself.

Is there any period maintenance I should be performing in an amp this age besides cleaning?  (I know, I know...."If it works, don't fix it!".;>)
I am not comfortable nor qualified to be working on HV circuits.

tnx es 73, Ken 5R8GQ/AD6KA
"Work is the curse of the drinking class!"-Oscar Wilde
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W1QJ
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Posts: 1521




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« Reply #1 on: November 29, 2008, 06:23:26 PM »

No, the AL-80B does not use the same transformer as the 2 tube Al-82, but the transformer is pretty husky for a single tube.  Basically the same parameters as the AL-80A with some upgrades like the electronic bias and the meters are different.  The basic RF deck layout is also different and the input network is located in the rear of the amp seperate from the tank circuit like the AL-80A.  The performcance is pretty much equal however.  It's basically a new version of the Al-80A and a good performer like the Al-80A.  Both amps use the 3-500Z to its max potential so there is no gain really in that area.  Both very good amps.
Lou
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5R8GQ
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Posts: 203




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« Reply #2 on: November 29, 2008, 08:56:13 PM »

I guess I worded my original question poorly. Sorry, my bad.

Does the AL80A use the same transformer as the AL80B?

"Both amps use the 3-500Z to its max potential so there is no gain really in that area."

Really? I run the AL80A 900-950 watts all weekend long in RTTY contests with no ill effects. So I can do that with the "B" model too? (usng 220v)

The reason I ask is that at 48 pounds, the AL80B would be a lot easy to travel with than the AL80A at 60 pounds + Pelican case +packing, which usually puts me over the International weight limit.

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W1QJ
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Posts: 1521




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« Reply #3 on: November 30, 2008, 06:12:14 AM »

"Specificly" I really don't know if they use the "same" transformer, I don't think they do, however I do know that both amps perform equally as well with power output.  The plate voltage and current abtainable with both are pretty equal.  Specificaly running 900 watts out with an AL-80B.....I don't know that for sure.  I don't think the Al-80A operating manual recommends running that kind of power on rtty, I don't think the Al-80B does either.  If you say the Al-80A can do that fine, but I don't know if the AL-80B will with no ill effects.  Surely it will do it, but for how long, I don't know.  I DO KNOW THIS... the tank circuit design is pretty much different on the Al-80B than the AL-80A.  The "B" model has alot of the HF coils mounted on a PC board whereas the Al-80A has them "floating" as you must well know.  From a matter of physics it might seem that the AL-80A would have better heat dissapation of coils not being on a PC board, which would matter greatly on RTTY mode.  I do think however that the transfomrers are equal, but may not be the same one.  Though I do not think either manual allows for 900 watts of rtty, calling the company and asking them would I assume net you a "no" answer.  I guess if someone else has done that power on rtty with an Al-80B they can report on that, the next best thing would be to have an opinion from Tom W8JI.
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W8JI
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« Reply #4 on: November 30, 2008, 03:12:49 PM »

The AL80B has a slightly larger transformer. It has better cooling, and has a true peak reading directional coupler that reads SWR as well as power accurately.

The transformer has more taps allowing wider range of input voltages.

It should handle RTTY just as well.

I think that was all you asked.

73 Tom

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K0CWO
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Posts: 419




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« Reply #5 on: December 01, 2008, 06:15:33 AM »

What accounts for the 12lbs difference between the AL-80A and B model?
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VR2AX
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Posts: 595




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« Reply #6 on: December 02, 2008, 04:48:59 AM »

Saphire and Steel.
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