Re: [amsat-bb] Keying the AIDC-3733 VCO

[John Harrington <johnh@xxxxxxxxxx>]

Mahlon, I don't on-off key a beacon.  There is nothing more distracting
while listening to a weak beacon and tuning a front end than have the
beacon suddenly start the CWID using on-off keying.  The best way, in
my humble opinion, is to shift the frequency slightly (300-400Hz) with
the CW.  This will have zero effect on your tuning- no interruptions-
while still complying with the 'ID every minute' rule.  I'll probably
first try a gimmick coupled to the crystal circuit via a 2N2222. After
all, you only have to move the crystal two Hz to get a 512Hz shift at
2400MHz.   By the way, I think you're right about that printed inductor
being the key to increasing the VCO range.  I'll try it when I get a
chance.  Thanks!   73 John

Mahlon Haunschild wrote:
> 
> One more thing, John:  If you are still thinking about how to key the
> AIDC-3733 local oscillator for beacon purposes, you might consider
> switching the DC feed to that "415" MMIC buffer amplifier.  I can't see
> an easy way to switch anything else in the PLL or VCO without creating a
> chirpy output.
> 
> Keying the MMIC won't be perfect.  I doubt that it would completely turn
> off the signal, but at least it will be identifiable.
> 
> regards,
> 
> Mahlon - K4OQ
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