Hi John

A crystal set is made of a coil in parallel with a capacitor (a tuned
circuit), one side of this feeds through a diode which provides the output
relative to the other side of the tuned circuit. Changing the value of the
inductance or the capacitance changes the resonant frequency. Adding
resistance in series with the capacitor or the inductor reduces the Q
(quality factor) of the circuit. The diode may exist in the input side of
the amplifier.

You may also want to look at your amplifier to ensure that it doesn't have
any gain at frequencies higher than those in which you are interested.

regards
Mark

> Well it jumped again tonight, right on schedule.  Fortunately I was right
there listening to KOLM radio, 1570 AM.  It jumped exactly as they went off
the air.  It must be their carrier signal during the day that keeps it in
one place and then when it goes off the signal changes.  Unfortunately, my
homemade aluminum foil box shield did not work.  At least not enough.  The
folks at KOLM say they are going to get their 24 hour license soon so
perhaps I will wait till then and depend on their steady signal to keep it
centered.  I would like to shield it however.  I could add more tinfoil but
it seems unlikely to help much.  Perhaps a wire cage of some sort?


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