18
Radio Control Board (RCB) Connections
Basic Checklist
Make sure you connect each radio, computer or other external device to the control
system RCBs using the DB9 connector on the front of the RCB.
DB-9 radio connections
The control system has a female DB-9 connector which
is used to connect to an external device including a
repeater, link radio, remote base radio or computer
system. The cable should have a male connector.
This picture is the DB-9 connector as seen on the front of
the control system.
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.