This is in response to Martin's method for calibrating a C508. I'm
curious as to whether its possible to screen a PIC so that it cannot
be "heard" by a short wave radio receiver. Is an aluminium casing
sufficient to block the PIC's RC oscillator signal?

>         If you have access to a short wave radio receiver that tunes in the
> 4 MHZ range and has an accurately calibrated frequency display,
> you could power up the pic and tune between 4 and 5 MHZ with the receiver's
> antenna near the PIC and look for the carrier of the oscillator's signal.
> There are apt to be lots of other signals in this frequency range so you may
> have to hunt a bit before you find the PIC.  Since it is a RC oscillator,
> it will probably be a bit shaky and may change frequency with the touch of
> a finger to the chip, but once you find it, you can start changing the
> calibration number until you get it as close to 4 MHZ as practical.
>
> Martin McCormick WB5AGZ  Stillwater, OK 36.7N97.4W
> OSU Center for Computing and Information Services Data Communications Group
>