User's Manual

4
SUB D 15 PIN CONNECTOR
The DR-145/445 is equiped with a 15 pin female sub D connector with the following functions:
Pin#
Function
1 Least significant channel select bit (CS0)
2 Channel select 1 (CS1)
3 Most significant channel select (CS2)
4 N/A
5 N/A
6 + 9 to 17 VDC input
7 N/A
8 Auxilary ouput
9 PC programing port
10 Volume control (RSSI option)
11 Auxilary monitor input (pull to ground to open squelch). Can be used for tone detect, see below.
12 Speaker output
13 Carrier detect output (pulls to 3.3 VDC through internal 390 ohms)
14 N/A
15 Ground
Channel Select (pins 2,1,0)
Three lines control the channel selection; CS2, CS1, CS0. The inputs have binary weighting of 4, 2 and 1 respectively.
They are internally pulled up in the microcontroller. Tying an input to ground gives it a zero weighting. Thus, if no inputs
are tied low, channel eight is selected (7 binary).
Power Input (pin 6)
A power source of 9 to 17 VDC with 2 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).
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 12 Hz to 2500 Hz. Higher load impedances will lower the low end frequency response. The
output is adjustable via the programmer. It is preset at the factory to give 1 volt peak to peak output when receiving a +/-
3 kHz (1.5 kHz for narrowband channel) deviated signal. Output range is 0 to 3 V peak-to-peak. It is suggested keeping
it below 2 V pp since the IF output is DC coupled and a frequency error of 1 kHz will cause a 0.2 V shift on narrowband.
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-145/445 programming
software must be run for configuring the transceiver (See programming the radio on page 10).
External Volume Potentiometer (pin 10)
Connecting a 10K pot to ground at this point will allow the speaker volume to be adjusted. For maximum range the
internal AUX_OUT gain should be set to a value that allows maximum volume with acceptable distortion when the pot is
set at 10K. Optionally, this pin can be used as an RSSI output. If desired, contact the factory.
Monitor Input (pin 11)
Normally the AUX_OUT and SPEAKER_ OUT are switched on only when a carrier with required tone, if
programmed, is detected. Bringing this input to ground will force the auxiliary and speaker outputs on. Alternately,
the monitor input can be used as an output. It gets pulled low when a carrier with correct tone is detected. The
following circuitry can be used as a carrier and tone detect output. Pin 11 can still be pulled low to monitor the
channel. Notice the high impedance 470 k ohm buffer resistor. Too low of resistance will turn the audio on.
Pin 11
470 k
15 k
Tone detect = 0
Vdc
15
k
Tone detect = Vdc
External circuit to use AUX_MON input as Tone Detect output