I am about to activate an RFPP-1000 amp which uses
1 - 8877 @ 2750v. (exactly what '5PRO recently described.)
My last remaining conversion change is to chose the Cathode
bias voltage to use. Here's what has been published:
K8RA-8877: 10Volt/1watt zener & 2N3055
" for 8.2v cathode voltage ".
Text indicates " bias for 18ma idle current."
( That can't be for the tube idle plate
current, can it ??)
W8ZR-8877: 12 volt/50watt 1N2812
150ma. idle plate current
Ameritron-AL-1500: 7.5 Zener
RA's-8877 in QST: 8.2 volt 50watt Zener for SSB
22 volt 50watt Zener for CW
(Ref: Radio Handbook W6SAI / 1996 ARRL Handbook.)
So my questions are:
================
-What bias voltage is needed for SSB ? for CW ?
-Advantages / Diadvanages of using a 50w Zener vs.
a 2N3055 & a 5 or 10watt Zener ?(Other than $$$).
Charlie - N1RR
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