Unit installation

1-3

Step #3: Connecting Your Receivers to the RLC-3

The radios connect to the RLC-3 using a male DB-9 connector (included). The pin-outs are listed

below.

Pin Number Description

1 Ground

2 PL Input (From your PL Decoder)

3 PTT Output (To the Transmitter)

4 Audio Output (To the Transmitter) 600

5 Audio Input (From the Receiver) 10K

6 Ground

7 COR (From your Receiver)

8 Ground

9 Ground

Connecting the Receiver COR

The first step in connecting your receiver is to locate an active receiver signal. If the voltage goes

from a voltage above 5 volts to ground when a signal is present, the signal is active low. If the

voltage goes from a ground to a voltage above 5 volts the signal is active high. Either polarity of

COR signal will work if the switch #2 (labeled "CR") is switched correctly. The signal must be able

to sink 4mA to ground. The input impedance of the RLC-3 COR input is 10K and it is diode

clamped with internal pull-up resistors. This allows it to handle input voltages of up to 40 volts

without damage to the controller. The COR input must not go below 0V (ground); this

would damage radio card's COR/PL input. Using one of the supplied DB-9 Male connectors,

connect your COR signal to pin #7. If the signal is active low, turn switch #2 on; if the signal is

active high, turn the switch off. The LED labeled RX will light when a correct activity signal is

received. If the LED lights at the wrong times, you probably have switch #2 set wrong. If the

LED does not light at all, the RLC-3 is not detecting your COR/PL input correctly. Use a volt

meter to make sure that the signal from your receiver changes from ground to above 5 volts (or

vice versa) when the receiver goes active.

Connecting a PL Input (optional)

If you wish to use a PL (CTCSS) decoder on any of the receivers, its detect line can be connected

to pin #2 of the appropriate connector in the same fashion as the COR input. You can select the

PL polarity with switch #3 (labeled "PL"). You will probably also want to use the audio filter on