[FoxHunt] IF out for foxhunting

[Michael J. Miller]

   A few years back, I built a 'sniffer', similar to the one in
"Transmitter Hunting Simplified".  It was basically a simple tank
circuit, a detector, and a high gain op-amp driving a meter.
   I got very frustrated with it's lack of sensitivity. Worse, I got
stuck one time chasing a powerful pager transmitter ( around 150 MHz)
that got past the tank circuit.
   I use a IC-2AT for hunting, which has no meter.  I didn't have the
active offset attenuator yet.
   My answer was to add a FET source-follower after the Icom's 1st IF.
This signal was coupled to the mic jack of the radio, since it is not in
use when hunting (mic jack function is maintained).  I added a 10.7 MHz
tank circuit in series with the 2M one in the sniffer, and a cable to
hook the sniffer's BNC to the mic jack.  I now have a linear 'S-meter'
that will give indications on any signal big enough to break the squelch
(or even AM or SSB).  When I get close enough, the antenna goes direct
to the sniffer.

73,

Mike
WB6TMH

---------------------------------------------------------
Jerry, WB8WFK wrote:

My home made AM receiver brings out the 10.7 Mhz IF to a front panel BNC

connector. I always monitor it using a CW detector (A HF RX in CW mode)
connected
to the monitor port. If any carrier is on frequency I know it because of
the beat
note produced in the CW receiver. Using this setup I can detect signals
that the
LPER can not copy.

Sometime ago we had an ELT mission  where the ELT was not modulated and
this
setup detected it. By the way several of the LPER guys where reporting
"no
signal".

Jerry