RF "sniffer" side tone generator

[Keith Harvey]

Recently exchanged posts re a "side tone generator"
that will work with boat anchors led me to offer this
solution.

I built a variety of RF sniffing devices using the
"RF drive On-Air Indicator" circuit in QST by 
Keith Austermiller KB9STR. My On-Air indicator
works very well using his design, and I find that
even a h/t will light it up. Depending on stray RF 
in your shack (or lack of) you may need to pick up
enough RF to drive it via a small coupler.

Anyway, it is no large challenge to use this circuit to
drive a small audio oscillator to give you a "side tone"
noi matter what rig you are keying. I suggest a small
reed relay to fire up the audio oscillator as carrier is
detected. A reed relay is quiet and the whole thing can be
powered by a 9volt battery.

The January QST also contains an article on a derivative
of this circuit. RF Activated Timer by Allen Poland Jr. K8AXW.


73 de Keith Harvey  VA3KRV
Campbellford, Ontario, Canada
Grid FN14ci
keith.harvey at sympatico.ca   or  va3krv at rac.ca

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