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Re: Variable Capacitance and Inductance
Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>
Tesla list wrote:
> Original poster: "David Thomson by way of Terry Fritz
> Hi Gary,
> Radios are tuned to crystals precisely because inductor/capacitor only
> circuits do drift.
SOME radios are tuned by crystals. Many are not.
cf any book of radio design, rf design, radio history.
With one _not_ tuned by crystals I routinely leave it
on, volume down, turn it up, and there is the BBC on
SW, 'just where i left it'. With another such, even
older, i was listening to 'Radio Australia' (Properly: ABC
Australian Broadcasting Company But that confuses people
in the US, with the OTHER ABC) one day. Next day i snapped
it on and there they were. (Both to a site in Eastern MA,
Capacitors can and do change value, as many people have
advised. Formulae for all (?) these effects are known
and routinely used. Similarly for inductors.