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[Amps] AL-80A - Grid Meter Replacement

Subject: [Amps] AL-80A - Grid Meter Replacement
From: Bill Coleman <>
Date: Tue, 17 May 2016 21:02:35 -0400
List-post: <">>
OK, I’ve got an AL-80A that works pretty well. Last April, I was tuning up on 
17m and I heard a SNAP, and suddenly the meters read all wacky. The Grid 
current meter would pin when keyed, and the plate meter was clearly off as well.

Long story short, I finally took the meter board out yesterday, and the 1.5 ohm 
3 watt grid shunt resistor clearly took a transient and failed open. That’s the 
reason for the funny meter readings. 

I’ve got a good handle on that fix, and also adding a protective diode as 
outlined by W8JI in order to prevent future failures.

NOW, to my question. Even though the meters were all wacky, I, like an idiot 
continued to USE my amplifier on occasion. Yes, with a little practice, I could 
safely tune it up even without working meters. Eventually, the pinning of the 
grid current meter, caused the needle to bend off.

How can I replace this meter? Ameritron doesn’t carry the AL-80A part any more, 
and the AL-80B uses a different cross-needle meter that won’t work. However, I 
see that the AL-572, the AL-811, the AL-82 and the AL-1200 all appear to use 
very similar metering circuits, and single-needle grid current meters. It could 
be that the meter movement is exactly the same, it just has different scales.

Does anyone know if any or all of these units can replace the Grid Current 
meter in an AL-80A??

Bill Coleman, AA4LR, PP-ASEL        Mail:
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

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