[FoxHunt] Fox Transmitter Plans?

[Marvin Johnston]

Hi Bruce,

The ICS chip does get turned off to stop the transmission, but it needs
to be turned on again (and reprogrammed) when it starts transmitting
again. One of the things I would still like to try is to see how quickly
and how clean the output signal is when the chip is just turned on and
off without any modulation being applied. It would also save a varactor
diode and a couple of resistors/capacitors in parts count :).

When the chip is first turned on, it starts transmitting on another
frequency for a couple of milliseconds or so until the PIC gets the
setup done.

I might add that hunting this signal with the L-Per AM receiver works
just fine. I've also tested a Ukrainian or Russian built AM DF receiver
with the signal and had no problems.

Marvin, KE6HTS

Bruce wrote:
> 
> On Thursday 13 June 2002 15:48, you scribbled:
> >
> > modulation is done by varying the crystal used to control the ICS307,
> > and seems to work quite well! We've done a little testing on the
> > units and it looks like the output is fairly clean with the 2nd and 3rd
> > harmonics down 30 dB from the main signal. It has a power draw of about
> > 33 mA while transmitting and about 5 mA in the off state. The deviation
> > seems to be running in the area of 1 - 2 KHz.
> 
> I imagine it wouldn't be too tricky to turn the clock source on an off at the
> CW rate rather than FM modulate the carrier ?  This would be more useful
> when hunting with a non-FM ARDF receiver.  Not sure how you go into the
> off state, and whether the clock source needs to be re-programmed to go on
> again.
> --
> Cheers,
> Bruce                                          ICQ: 32015991
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