[Heathkit] off topic question, sort of

[jeremy-ca]

Any tube can be evaluated as long as the constant current curves are 
available which it is for the 4-400.
Build up a test jig with filament, adjustable bias, screen, and a HV of 
1000-1500V. Also some form of cooling; Ive used a squirrel cage unit blowing 
on the side of the tube for up to 4-1000A's.
The bias supply will need to have negative and positive output.

If you have a SB-220 (or just about any 3-400Z/3-500Z amp) available it can 
be plugged in and evaluated as GG in the CW position. Drive it with 40-50W 
for a short period ONLY as the cooling fan is insufficient for the seals 
hidden behind the metal shell.

Carl
KM1H

----- Original Message ----- 
From: "Murray Grandy" <mgrandy at telus.net>
To: "HEATHKIT LIST" <heathkit at mailman.qth.net>
Sent: Sunday, October 07, 2007 2:55 AM
Subject: [Heathkit] off topic question, sort of


DOES ANYONE KNOW OF A WAY OF TESTING TRANSMITTER TUBES SUCH AS 4-400. WAS 
THERE EVER ANYTHING IN ANY OF THE ARRL HANDBOOKS. SEEMS LIKE THERE MUST BE 
SOME WAY TO JERRY RIG SOMETHING THAT WOULD DO A BASIC KINDA TEST.
Murray
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