6
DESCRIPTION OF INPUT/OUTPUT
Channel Select (pins 3,2,1)
Three lines control the channel selection; CS2, CS1, CS0. The inputs have binary weighting of 4, 2 and 1
respectively. Tying an input to ground gives it a zero weighting. Thus, if no inputs are tied low channel
eight is selected.
Power Input (pin 6)
A power source of 8 to 15 VDC with 0.5 Amp capability should be connected here. Once power is applied
to pin 6 of the radio the microcontroller will start and load the receive frequency of the channel
designated by CS2, CS1 and CS0 (pins 3, 2 and 1). The radio will beep out the channel number on the
speaker line.
Auxiliary Output (pin 8)
An output loading of 600 ohms or greater should be applied to this output. With a 600 ohm load the
output exhibits a frequency response of 6 Hz to 3000 Hz. Higher load impedances will lower the low end
frequency response. The output is adjustable with an internal potentiometer. It is preset at the factory to
give 1 volt peak to peak output when receiving a +/- 1.5 kHz (+/- 3 kHz for WB) deviated signal. If the
correct CTCSS or DCS tone is present the radio will unsquelch the SPEAKER and AUX_OUT lines.
Programming Port (pin 9)
This line is a bi-directional programming port to be connected to a RITRON programming cable. The
other end of the programming cable connects to the PC’s serial port 25 pin D-sub connector. The
appropriate DR-142 programming software must be run for configuring the transceiver.
Auxiliary Output Monitor Input (pin 11)
Bringing this input to ground will switch the auxiliary and speaker outputs on. Normally the AUX_OUT
and SPEAKER_ OUT are switched on only when a carrier with required tone is detected. This pin can be
used as a tone enabled carrier detect output. It will be pulled to ground if a carrier with the proper tone is
detected. Otherwise, it will be pulled to Vcc via a 1.5 k ohm resistor
Speaker (pin 12)
A speaker with 8 ohms or higher should be connected to pin12. A nominal 1 watt of audio power at 10%
THD is expected. If the correct CTCSS or DCS tone is present the radio will unsquelch the SPEAKER
and AUX_OUT lines. The speaker volume is preset by an internal potentiometer (R350) to yield 2 volts
RMS into 8 ohms. If your application requires a different audio level two options exist. One is to open the
transceiver unit by removing the 4 corner screws on the connector end of the radio case, pull out the
PCB and reset the volume potentiometer (R350). The second is to place a power resistor or
potentiometer in series with the output and speaker to reduce or adjust volume.
Carrier Detect Output (pin 13)
This line will be pulled to 5 volts through a 390 ohm resistor when a carrier is present.
