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

Paul Christensen w9ac at arrl.net
Mon Jan 23 16:19:50 EST 2023

The most recent Eimac 8877 datasheet from CPII shows a 3-minute filament
warm-up time:


The 07/01/1975 datasheet revision that Vic referenced shows 90 seconds:


Typical operation of the Alpha 77 series amps is to step-start filament and
1/2 plate voltage together (approx. 2KV).  Then after the warm-up period
completes, the operator may engage full HV at 4 KV.  

Paul, W9AC

-----Original Message-----
From: Amps <amps-bounces at contesting.com> On Behalf Of Colin Lamb
Sent: Monday, January 23, 2023 4:06 PM
To: Fern Rivard <crc at cyberlink.ca>; amps at contesting.com
Subject: Re: [Amps] 8877 - HV with heater, or later?

I recall that Eimac said 90 seconds was ok for the 3cx800 tube.  Then they
published a later publication that said 180 seconds was right.  I think the
90 seconds was too short.

Colin  K7FM
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