TECHNISONIC INDUSTRIES LIMITED
www.til.ca
TFM-30 Installation & Operating Instructions
TiL 98RE244 Rev n/c Issue 9
3-12
3.13 MAIN AND GUARD SQUELCH ADJUSTMENT
The squelch, on both the main and guard receivers, is factory set to open at approximately
1.0 micro volts. This adjustment can be made or altered to suit local conditions as follows:
1.
Set the main receiver of the transceiver to 39.500 MHz. Connect a signal generator
to the antenna input of the transceiver.
2.
Set the signal generator to produce a ± 3 kHz deviation with a 1 kHz tone on
39.500 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 potentiometer, R3 through the access hole
located on the bottom of the transceiver chassis (see FIGURE 3-5).
4.
Repeat the above procedure to adjust the guard receiver squelch setting using guard
receiver squelch adjustment potentiometer, R4 (see FIGURE 3-5).
3.14 TRANSMITTER DEVIATION ADJUSTMENT
1.
Remove and retain the eight #4-40 screws securing the top cover of the transceiver
to its chassis. You should now have access to the Main Rx/Tx Module.
2.
Set the transceiver operating frequency to 40.000 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.
3.
Key the transmitter and input a +13 dBm (3.46 VRMS), 2.5 kHz audio signal into
the microphone input.
4.
Adjust the wideband deviation limit potentiometer, R21 on the main Rx/Tx module
(see FIGURE 3-6) to produce a ± 4.2 kHz deviation. Adjust the narrowband
deviation limit potentiometer, R16 on the main Rx/Tx module to produce a ± 2.1
kHz deviation.
5.
Verify that the deviation does not exceed ± 5 kHz for wideband and ± 2.5 kHz for
narrowband on the following frequencies: 30.000 MHz, 40.000 MHz and 50.000
MHz. Readjust R21 or R16 as required, if the deviation exceeds ± 5 kHz or ± 2.5
kHz, respectively.
6.
Place top cover on transceiver chassis and secure all eight screws.
3.15 GUARD RECEIVER AUDIO LIMIT FEATURE
Upon special request, 1 mW of guard receiver audio bleed with the guard volume control in
the fully CCW (OFF) position, can be provided. This feature can be disconnected as follows:
1.
Remove and retain the seven #4-40 screws securing the bottom cover of the
transceiver to its chassis.
2.
Find the jumper located at the bottom of the front panel is connected between the
CCW position of the guard audio potentiometer (R2) and ground. Remove this
jumper.
3.
Replace the bottom cover of the transceiver and secure with the seven screws
removed in step 1.
