>
>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.
>
smoke
>
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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