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Re: [Amps] Triode Amps

To: <>
Subject: Re: [Amps] Triode Amps
From: "Paul Christensen" <>
Date: Fri, 3 Dec 2021 09:29:24 -0500
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> "My favorite triode for 1500 watts all day is a single 8877. 4KV and 30 
> watts drive."

Over the years I've managed to squirrel away three NOS Eimac 8877s.  Of the few 
tube failures since owning an Alpha 77Dx amp, most were related to Eimac's heat 
dam alignment issue with some 1980s date code tubes -- and, excessive filament 
voltage from high utility mains.  The latter was solved with the inclusion of a 
filament choke that drops voltage to 5.0V from AC mains that typically runs 
130V/260V.  I probably have one of the very few 77Dx amps that has not been 
converted to an Sx.  I've never seen a need for the conversion.

New list members may want to take note of a post long ago from Dick Ehrhorn, 
founder of ETO/Alpha.  In the link below, Dick describes 8877 failure dates 
along with meeting notes with Eimac personnel during the time ETO was in the 
MRI manufacturing business.  When purchasing a used 8877, I would refer to 
Dick's timeline.

Paul, W9AC 

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