99RE255
TDFM-136 Installation & Operating Instructions
3-6
Technisonic Industries Ltd.
3.7.8 Memory Up/Memory Down
Remote scrolling through the 25 memory positions can be achieved by providing a ground to pins 4 (up)
and 5 (down) through a momentary contact cyclic switch.
3.7.9 Data Input/Output
Channel data may be transferred to and from the unit using RS-232 communications protocol via pins
2 and 11.
3.8 Transmitter Side Tone Level Adjustment
The sidetone level is set at the factory; however, this level can be altered to suit local conditions
as follows:
1.
Set the transceiver operating frequency to 155.000 MHz and connect an appropriate test
receiver to the RF output connector. Ensure that the output of the transceiver is terminated
into a proper dummy load.
2.
Key the transmitter and input a 1kHz audio signal @ -10 dBm (0.25 VRMS) into the
microphone input.
3.
Select the side-tone adjust command and then adjust the side-tone level using the guard
volume control to produce a +3.0 dBm (1.0 VRMS) 600 ohm audio output.
3.9 Main and Guard Noise Squelch Adjustment
The squelch on both the main and guard receivers is factory set to open at approximately 0.5
microvolts. This adjustment can be altered to suit local conditions as follows:
1.
Set the main receiver of the transceiver to 155.000 MHz. Connect a signal generator to the
antenna input of the transceiver.
2.
Set the signal generator to produce a
?
3 deviation with a 1kHz tone on 156.000 MHz.
Increase the signal generator RF level from 0.1 uV until the squelch indicator LED is on.
Verify the receiver SINAD ratio is between 12 and 14 dB.
3.
If not, re-adjust main receiver squelch via the main receiver squelch software command.
4.
Repeat the above procedure to adjust the guard receiver squelch setting using guard
receiver squelch adjustment software command.
