[Amps] Henry 1KD-5 Bias

[Michael J. Tubby B.Sc. (Hons) G8TIC]

----- Original Message ----- 
From: "Randall DuCharme" <ad5gb@yahoo.com>
To: <amps@contesting.com>
Sent: Friday, October 04, 2002 3:38 PM
Subject: [Amps] Henry 1KD-5 Bias


> Greetings Gurus,
> 
> Wondering if someone knows for sure where the idling
> current for a single 3-500Z based amp should be.  My
> 1KD-5 has a ZSAC of about 32mA (3300V Ep) but in
> looking at an Eimac datasheet for the 3-500Z, this
> appears to be too low for AB2.  Am I mis-understanding
> something or do I have yet another problem with this
> thing?
> 
> 
> Many thanks!
> 

I run single 3-500 amps with around 70-90mA depending
on HT, etc.  Assuming that the tube is good, check the heater
volts are in spec. then if they are check the voltage acorss
the bias zener.

If you have a 12-15V zener consider replacing it with a 6-9V
zener. If you have a 6-9V zener consider replacing it with a
short circuit...

I have two 3-500 amps on 6m the tubes are from the same
batch but one has seen a lot more service than the other. With
3700V on the Anode one needs a 12V zener and the other
nothing at all to stay in the ZSAC of about 70-90mA.

Mike G8TIC/M0VHF