Date: Sun, 10 Apr 2016 14:15:10 -0400
From: "John Flood" <k4dlx@bellsouth.net>
To: <amps@contesting.com>
Subject: [Amps] warm up time for TX tubes
New to this reflector.
Hope someone can help me understand tube warm up requirements.
Specifically, What are the necessary conditions for voltages at plate ,
screen and control grid during Warm up for indirectly heated tetrode tubes.
I have seen directions that say no plate voltage during warm up, but some
amps (MLA2500) apply plate voltage and limit cathode current to a few mA by
self-bias during warm up.
What I have in mind for my amp with gu74b (4cx800) is to apply fil voltage
for 3 minutes while screen is at 0v, plate is full on and
G1 is biased to cutoff (approx. -75v).
Is my approach workable?
And What are the necessary conditions condition for the tub during warm up?..
Thanks in advance for your help
John K4dlx
## there is no requirement to shut off the B+ while the fil is heating up.
All that is required is to have the plate current biased to cut off.... just
like
RX, and no drive applied.
## with full B+, nothing will happen..as long as no drive applied, and plate
current cut off. Even Eimac sez the same thing.
Jim VE7RF
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