[Amps] HV/Tune-up Procedure for AL-80A

[jsb at digistar.com]

On Fri, 12 Nov 2004, Scott Manthe wrote:

> I just got a very nice Ameritron AL-80A, which seems to be in very nice
> shape- certainly excellent cosmetically. Unfortunately, the fellow I
> bought it from neglected to pack the manual with it and I'm expecting it
> in the mail in a day or two. In the meantime, I'm wondering if anyone
> can let me know what I should see for high voltage (I'm seeing about
> 3000-3100 volts, on a 115 volt line)

It's not so much the idle HV but what the voltage drop is between ZSAC
(key down but no signal from exciter) and full output - if it drops 500V
or more you should connect it to 220VAC.  A 500V drop in HV will cause a
detuning effect and splatter.

Tune for max output at 20W from the exciter, then increase exciter output
until plate current reaches around 350mA.  You should also turn the LOAD
control a tad to the right (I believe that is the direction to rotate the
knob so that the AL-80A load cap unmeshes, you should verify) which will
reduce grid current and buy yourself a little linearity.  About 50 watts
decrease in power output is sufficient to lower grid current and improve
linearity.

If you run CW and notice 400-500V drop, tune for max out and do not use a
key pulser - as long as you are very close to max output you can hold the
key down for 3 or 4 seconds to touch up the tuning.

If you run SSB and have 400-500V drop in plate voltage you should do the
same as for CW but keep in mind that you will be better tuned for full
output and less optimally tuned for softer voice.

The short answer is to get 220V into the shack if you've got that much
drop in plate voltage.


No one is going to notice the difference between 800 watts and 1600 watts
except you when you are looking at the wattmeter, and perhaps the people
near your frequency when you're splattering on them hi no need to squeeze
every milliwatt out of the amp!


73 Jason N1SU