[Lowfer] Hifer FSK?

[Ed Phillips]

Bill Ashlock wrote:
> 
> John D and group,
> 
> >Any of the designs using the Epson programmable oscillator ICs can be
> >frequency shifted with a relatively small variation of Vcc.  Might be worth
> >a bit of experimentation.
> 
> Thanks to Eric for the reference to Lyles good Epson Oscilator article.
> Turns out that a drop in Vcc from 6v to 2v produces an increase of ~ 0.3
> ppm. This is ~0.5 Hz at 1.704 MHz for the Medfer application and ~5 Hz at
> 18.572 which approximates the Hifer application.
> 
> Lyle: Was this a quick change in frequency or one relating to an internal
> heating effect (or both)? I noticed that the input power drops considerably
> for the 6v to 2v Vcc change.
> 
> Bill A

	At best that's a lousy way to FM a crystal oscillator.  For the small
shifts which would probably be employed in a beacon a varicap in series
with the crystal would be preferred.  You might have to build the
oscillator but that's no big deal.

Ed