21
AS-3 Audio Squelch Board
Pin 1
High impedence Rx audio input from receiver. Input can range from 0 to 2v
peak-to-peak. Anything around 1 v p/p works great. Rx audio may be
unsquelched.
Pin 2 COR ("Carrier Operated Relay"), an active low signal. When the carrier is
present, the COR pin must be pulled to ground.
Pin 3 Ground
Pin 4
PTT ("Push To Talk"), an active low signal. This is an open collector output that
pulls to ground when the controller wants to key the transmitter. The output
can sink a maximum of 250 ma.
Pin 5 Low impedence audio output to the transmitter. Nominal 1v p/p output. Can
be adjusted from 0 to about 4v p/p.
Pin 6 PL decode input active low. Pull this input pin low to indicate the presence of
the proper PL or DPL tone being decoded.
Pin 7 Serial data input. TTL level ASCII input used with serial programmable remote
base radios.
Pin 8 Serial data output. TTL level ASCII input used with serial programmable
remote base radios.
Pin 9
Fan control output. This is an open collector output which is pulled to ground
to actuate a relay that will turn on the cooling fan on the transmitter. The output
can sink a maximum of 250 ma.