"So when one of these waves shows up. the breakdown potential of the
air-variable cap doesn't even matter?
>
> So, having a plate tuning capacitor that breaks down at 5 kv will not
> necessarily prevent arcing at a plate switch that is rated a 6 kv.
>
... even though they both connect to the same point - the outgoing
end of the DC blocker cap.
Amazing, Colin, simply amazing."
Rich, you are good at putting words into people's mouth, then using those
words to discredit someone.
Parasitics are rare in vhf amplifiers. They are not rare in hf amplifiers.
The difference is longer leads in hf amplifiers. In hf amplifiers, the
bandswitch is not often connected directly to the plate tuning capacitor -
it is connected with finite lead. If there is a vhf oscillation, the
voltage occuring at the switch may well be different than the voltage at the
capacitor. The sloppier the construction, the greater the lead length and
the greater variation possible for a vhf oscillation.
Of course the voltage variation would not be great if the lead length was
minimal and the frequency of oscillation was in the hf range. If the lead
length is 3" and the frequency of oscillation is 144 MHz, then the voltage
difference between the two points could be 15%.
Colin K7FM
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