I doubt if that has much effect on our low power tubes Mike but the "boys"
with the 10-20KW rigs might be interested.
I also never had to replace any of the WW2 era TX tubes while in the USN
and
those were cycled on only when necessary.
Much ado about nothing for this forum. When was the last time you saw a
3-500 with a bad filament?
## Those devices that rf parts sells... that go into one or both legs of
the fil xfmr have to be
in stagnant air. They normally run hot. IF there is forced air on em,
their resistance will increase.
## The triac ramp up circuit will also work, but then you have no way to
tweak the fil voltage.
A switching supply will work, but the inrush current on the tube will
cause the switcher to shut itself off.
The switcher has to be sized a lot bigger.
## W8JI claims a lot of the chinese 3-500Z tubes wont produce low imd,
unless the fil V is at least 5.1 to 5.2 V.
A simple step start will step start the B+ and also the fil..and both at
the same time...plenty good enough for amps
like L4B, etc.
** Thats more of JI's BS to meet the corporate goal of the advertised 1000W
PEP in an AL-80B.
Even Eimacs have poor IMD when pushed that hard.
When the AL-80A first hit the market it was easy to tell one as they were
IMD boxes when driven at 100W.
After awhile the Russian tube garbage hit the bands to add to the noise.
Carl
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