[AMPS] 2 x 3-500z amplifiers

[Martin Ellis]

Good morning,
While activity is quiet on the reflector, I would like to raise
a question about the TL922 amplifier:

How can we assess the performance of individual tubes in a TL922?
For example, after a major event is one tube faulty or do we need to
replace both tubes?
Or if output is slowly going down, is one tube carrying the work load,
or are both tubes getting "soft".

It does not help to view the anode color, as one tube seems
to get more cooling air than the other. 
As the filaments are in series, you cannot pull one tube,and all
metering is of course for both tubes.  Is it permitted to lift
one plate cap and operate the amp?

Regards,
Martin ZL1ANJ

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