[Top] [All Lists]

Re: [Amps] 8877 - HV with heater, or later?

To: Jim Barber <>, Amps group <>
Subject: Re: [Amps] 8877 - HV with heater, or later?
From: gudguyham--- via Amps <>
Reply-to: "" <>
Date: Mon, 23 Jan 2023 17:56:49 +0000 (UTC)
List-post: <>
The 3cx800 tubes are in the same class of tube as the 8877 and no ham amplifier 
using it holds of the plate voltage.  Same goes for 8877 except for the the 
Ameritron AL1500.  s long as the cathode does not see drive until warmed up 
that’s the only requirement.  K don’t think Eimac even suggests holding g of 
plate voltage but of course that are definite about no drive power being 
applied.  I suppose if you hold off the HV it could be considered an extra 
precaution measure.  

Sent from the all new AOL app for iOS

On Monday, January 23, 2023, 12:26 PM, Jim Barber <> wrote:

I'm overhauling a vintage 8877 amp, and it occurs to me that I've never
seen a definitive answer to this question:

Should HV be held off on a 8877 until the heater warm-up timer expires?

Not that I claim any particularly deep or insightful knowledge of such
things, but it seems to me that if the cathode has cutoff bias that it
wouldn't make any difference when B+ is applied.

I did find a reference to this question in the amps archives, but every
design I've looked at recently holds the HV off until the cathode is ready
to go.

Maybe there's more to it than I'm seeing? I may use a separate HV switch on
the front panel anyway just to allow for gettering, but I'd still like a
consensus on the question.

Amps mailing list

Amps mailing list
<Prev in Thread] Current Thread [Next in Thread>