I have been reading lately on this Reflector allot of great information about
High Power Transmitting tubes, and about the good and bad about the Russian
tubes.
I have an Amp that uses a pair of the 3cpx80A7 tubes , They are about 1 year
old, and are Eimac brand. They are working perfectly!
I thought it would be a good Idea to have a pair of spares, for the amp. I
put out a few Want Ads, and received several responses , for New OLD stock
(NOS), and some for Medical Pulls.
A pair of these tubes NOS or Medical Pulls were quoted to me in the $600-$800
range and more.
I asked about any kind of warranty and ,only one fellow would guarantee that
they would work, the rest of the offers were essentially AS IS!
After reading the info here in AMPS about Conditioning Tubes, I have a few
questions:
1. Upon receipt of a set NOS or Medical pulls , how should the average Ham
with limited test equipment test the tubes before placing them in the
amplifier?
I am thought that maybe an Ohmeter should be used to first test the tubes
for shorts, grid to filament and then maybe a 220 Variac connected to the
Amplifier AC Input lines . But I am not sure of the voltages or timing to
condition the tubes?
2. If the tubes work OK, and the original tubes are put back, what would be a
reasonable time to rotate the Med Pulls or the NOS tubes purchased as spares? I
have read that the tubes need to used occasionally to burn off any air that may
have been leaked into the tube?
Your comments would be appreciated>
rob
Sincerely, Rob, Peggy , and Maggie Sue Papillion
"The Venerable dead are waiting in my library to entertain me and relieve me
from the nonsense of surviving mortals."
Samuel Davies
1725-1761
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