Tom says
>Unless you have a very high Z in the shunt components of the HF
>tank at VHF, or some pretty poor wiring or connections, it is
>impossible to have a VHF parasitic arc across a bandswitch.
I'll play devil's advocate here.
Assume that the parasitic circuit consists of the tube output capacity in
series with the inductance of the connection between the plate and the tune
capacitor (and the inductance of any parasitic suppressor) and the tuning
capacitor. Bit like we used to 'series tune' things like 6146s and 5763s on
2 metres. Now, when we are on 10m especially, and the tune C is getting low
(in Jon's case, to the same order as the tube output capacity), is it not
possible that a parasitic under those circumstances could have a voltage
high enough at the tune Capacitor to exceed the bandswitch rating? If the
tune C is equal to the tube output C, then the voltages would be about
equal, while the 'parasitic' tank would be effectively unloaded, and could
thus be of high Q.
I offer it as a possible explanation. Start shooting!
73
Peter G3RZP
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