Hi Dave,
I've said it many many times, as have many other people. As a
matter of fact I said it in the post where you said I didn't say it.
Despite that, I'll repeat it again.
> You seem to have eliminated all the things that DON'T cause arcs, what is
> the real cause?
Band switches primarily arc from a load fault or underloading of the
tank at the operating frequency.
That fault can be from a poorly sequenced antenna relay, a
defective component (like a lightning arrestor that breaks down
when it shouldn't), or many other causes.
As an additional note, this aggravated by excessive HV in the PA
and by the spikes or transients that occur on the leading edge of
many rigs.
It's a pretty basic concept that has always been well known.
At VHF, the tuning capacitors reactance is so low the tube is very
unlikely to ever drive enough current to develop the high voltage
required to arc a switch downstream from the cap. At the resonant
frequency, the energy storage is enough to build considerable
voltages if the antenna or load is not absorbing the power and the
bandswitch will see it all.
73, Tom W8JI
w8ji@contesting.com
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