> From: "jeg" <jackg@one.net>
> I had a Kenwood TS-922A that had a bandswitch arcing problem.
> Keying the amp while running VOX would result in an arc
> typically once per 20 transmissions.
> Upon investigating, I found that the problem was that the RF input
> and output DPDT relay was a large, SLOW, contactor style relay that
> was energized at the same time as another smaller, faster relay that
> controlled the bias and indicator lights. I replaced the RF
> input / output relay with a P&B 3PDT relay, and used the third
> pole to switch the bias.
> After this change, all bandswitch arcing ceased completely. I
> replaced the burned bandswitch, and never had an arc again over a
> period of about 6 years of use with VOX.
That's a common cause Jack.
Another common cause is an antenna system fault, or incorrect
loading.
I remember one guy who sells nichrome kits claimed a certain K5's
TL-922 problem was a VHF "parasitic", and the guy popped up and said
"No, it was a bad lightning arrester. I replaced it and the tank
arcing stopped".
By far the most common cause of tank arcing is improper tuning, or a
sudden lack of proper load.
When the PA is trying to crank out 1000 watts, and the power suddenly
has no place to go, the voltage gets pretty darned high in the tank.
73, Tom W8JI
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