Here's something I've been pondering, and I'm wondering if it is worth pursuit:
I have an AL80A amplifier (it's stable, but thanks for asking). The 3-500Z
in it is the original Eimac tube, and does quite well. The amp has an
internal Ameritron QSK switch (works great). I don't want to cycle the
filament much, so I often turn it on and leave it in "standby" mode while I
operate, using it only as necessary, which isn't every time I
operate. While in standby mode, the filament is running at full voltage.
One of the limiting factors in filament life is hours of operation, and
they last a lot longer running at lower voltages. Of course, emission is
reduced at low voltages, so I wouldn't want to do this while actually
generating RF with the amp.
Here's the question: Would it be worthwhile to place a small resistor (say
something between 0.05 and 0.1 ohm) in series with the filament while in
standby? Or is this a no-win scenario, because the small amount of thermal
cycling would stress the filament enough to send it to an early grave?
73,
Kim Elmore, N5OP
Kim Elmore, Ph.D.
University of Oklahoma
Cooperative Institute for Mesoscale Meteorological Studies
"All of weather is divided into three parts: Yes, No, and Maybe. The
greatest of these is Maybe" The original Latin appears to be garbled.
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