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RLC-4 V1.79 Copyright © 1998 Link Communications Inc. 9/18/98
Connecting the Receiver Audio
- 2 types of audio can be used on the RLC-4 controller:
Type 1: De-emphasized audio (Speaker Audio)
Type 2: Discriminator audio (Raw Unsquelched Audio)
- If type 1 audio is used, remove the audio jumper for the radio port. This removes the
de-emphasis filter from the circuit. If you are using discriminator audio, connect the jumper across
the 2 pins. The filter will not allow PL to pass through the controller. Contact Link
Communications Inc. if you need to pass PL through the controller (it is better to filter it out and
re-inject it).
- The audio input is connected to pin #5 of the male DB-9 connector
- The audio adjustments will be described in Step #4.
Jumper J7 - Port 1 Audio Filter De-emphasized jumper
Jumper J8 - Port 2 Audio Filter De-emphasized jumper
Jumper J9 - Port 3 Audio Filter De-emphasized jumper
Jumper J10 - Port 4 Audio Filter De-emphasized jumper
Step #4: Connecting Your Transmitters to the RLC-4
Transmitter PTT
- The RLC-4 produces an active low PTT signal (ground when PTT is active). This output is
buffered with an open collector type driver capable of sinking 150mA. There is a built in 30V zener
clamping diode to protect the PTT MOSFET from the high voltage spikes that can be caused by
interfacing to a PTT relay coil. Your transmitter PTT input should be connected to pin #3 of the
DB-9 connector.
Transmitter Audio
- The RLC-4 provides a 10K output impedance to your transmitter’s audio input.
- The transmitter audio is connected to pin #4 of the DB-9 connector.
- If it is not already, the DB-9 plug can now be plugged into the appropriate jack on the controller.
- You may need to adjust the mike level pot on your transmitter to give the controller more range
in its adjustments. A good rule is to set the transmit pot on the controller mid scale in its
adjustment. Then set your transmitters mike level pot to obtain the correct deviation.
Step #5: Adjusting the RLC-4 Controller
- Locate connector J1 on the RLC-4's main board. (It is the 10 pin female connector located near
the tone level adjustments). This test bus will provide the signals that we need to adjust the audio
inputs on the RLC-4. In order to maintain audio deviation during channel switching, all of the
receiver inputs must be set to the same level. These signals can be measured with an oscilloscope
or an AC voltmeter. If you are using an AC voltmeter, remember that it reads AC signals as RMS
values (1 volt peak-to-peak equals 0.35 volts RMS). In order to obtain an audio signal on J1, a
valid COR or PL must be received. Once a valid access signal is received, the RLC-4 will un-
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