Alek Petkovic wrote:
> G'day Rob
>
> It is not any "camp" that makes the claim of shortened emissive life
> due to high filament voltage. It is Eimac, in its "Care And Feeding"
> book. For every 3% increased in filament voltage, the life is
> shortened by 50%. In the case of Ameritron's 10%, one would expect
> around 12% of normal tube life. (Didn't someone recommend Ameritron
> here a couple of days ago on a different thread? Ha ha)
>
Don't forget, that line voltages can vary over quite a wide range and
there are taps on many transformers to adjust for the proper output
voltage. Line voltage can easily vary up to around 10%. I don't know
what the specs are now for AC, but it "used to be pretty tight". Still
I remember a couple of times back in the 60's and 70's of calling the
power company because we were going through light bulbs like crazy. We
were at the head end of a very long line so we ran near the upper limit
just to get enough voltage to the other end.
Current line voltage right now is 118/236. I've never seen it go outside
115-118 except for some failures.
73
Roger (K8RI)
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