I don't have an answer but your post and a couple others I've seen beg this
question. What is all this worrying about how many times a 3-500z is turned
on and off?
My ancient Eimacs could care less. What am I missing here?
73,
Steve wd0ct
> 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
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