Having seen what may happen to the geometry of a cold filament because of an
inrush current, I wouldn't like to switch on an off many times my amplifier.
On the other hand, even modern TV sets have a st-by feature that keeps warm
cinescope filament when the TV set is not used between short periods.
Considering the typical amateur use in which the tube life time (hours)
isn't practically ever the reason to replace it because other aging factors
(expecially with ceramic) and failures generally came earlier than pure
"consumption", I wouldn't mind to keep the amplifier on when receiving.
Merry Christmas & HNY.
73,
Mauri I4JMY
----- Original Message -----
From: "Chuck Counselman" <ccc@space.mit.edu>
To: <amps@contesting.com>; <henry@contesting.com>
Sent: Sunday, December 24, 2000 5:49 PM
Subject: [AMPS] On-off, or leave it on?
>
> My amp uses an Eimac 3CX3000A7, whose cathode is directly heated. (It's a
> thoriated-tungsten filament, IIRC.) An often-touted virtue of such a tube
> is that it requires just a couple of seconds of warmup time; in other
> words, it's "instant-on."
>
> My usual mode of operation is "search-and-pounce" DXing. In this mode I
> may spend 30 minutes scanning the band for a "new one," and then use the
> amp for a QSO lasting just a minute or two.
>
> What's best for the tube? Should I leave the amp on all the time? Or
shut
> it off when I finish a QSO, and switch it back on when I'm about to make a
> call?
>
> Merry Christmas es 73 de Chuck W1HIS
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