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Re: [Amps] AL80A PROBLEM

To: Jim <>
Subject: Re: [Amps] AL80A PROBLEM
From: Thomas Walsh <>
Date: Wed, 21 Nov 2018 10:06:01 -0700
List-post: <>
Sounds like the amp is doing it's job, amplifying whatever shows up on its 
input. You mentioned seeing a slight bump in power from the exciter, there you 
go, the amp is merely amplifying what it sees although more noticeable. Check 
your exciter with a wattmeter between the exciter and amps input. Many modern 
transceivers today put great emphasis on the receivers but still have cheap 
china crap in the tx. And transmitters are easier than receivers! The reason 
for this and alc overshoot etc., is because it is controlled by a dac, which is 
updated depending on #1 clockspeed and #2 the code that's running in the radio. 
On some radios, the default is full power and the updated dac value reduces it 
to the user setting, on every keyup! BTW, this also explains some of the alc 
overshoot problems. A byproduct of merging analog with digital.

Sent from my iPad

On Nov 20, 2018, at 10:47, Jim <> wrote:

What are you driving it with? Do you have ALC hooked up? What mode?

Jim W7RY

> On 11/18/2018 8:53 PM, BY THE LAKE wrote:
> My AL80A began acting up a few weeks ago...nothing serious but baffling. On 
> 160 and 80 mainly, when I tune up with about 30W drive, after a second or two 
> key down grid current jumps by about 50 ma, plate current by perhaps 25ma and 
> power output by about 60 watts or so. I have done all the usual maintenance 
> things and even tried my spare tube but the condition persists. It does not 
> seem as noticeable with higher drive and power output.  Watching the power 
> output meter on my transceiver, a slight increase is visible coinciding with 
> the changes in the amp's meter readings.  Sort of suggests a tube about to go 
> bad?  But two of them, one a little-used Amperex??
> The onset of this condition coincided with some reports of an echo on my 
> signal!
> Anybody ever run across this type of thing?
> Bill VE3NH
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