TECHNISONIC INDUSTRIES LIMITED
www.til.ca
TAF-550 Installation & Operating Instructions
TiL 96RE187 Rev D
2-6
2.2.5
Transmitter Sidetone Level Adjustment
(1)
Set the transceiver operating frequency to 156.000 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 -10 dBm (0.25 VRMS), 1 kHz audio signal into the
microphone input.
(3)
Adjust the sidetone level potentiometer (R37 on MCU module) through the access hole
located on the left side of the chassis (see Figure 2.3) to produce a +3.0 dBm (1.0
VRMS) 600 ohm audio output.
2.2.6
Main And Guard 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 made or altered to suit local conditions as follows:
(1)
Set the main receiver of the transceiver to 156.0 MHz. Connect a signal generator the
antenna input of the transceiver.
(2)
Set the signal generator to produce a ±3 kHz deviation with a 1 kHz 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 potentiometer, R3 through the access hole located
on the bottom of the transceiver chassis (see Figure 2.3).
(4)
Repeat the above procedure to adjust the guard receiver squelch setting using guard
receiver squelch adjustment potentiometer, R4 (see Figure 2.3).
2.2.7
Transmitter Deviation Adjustment
(1)
Remove and retain the eight (8) No. 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 156.000 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 +10 dBm (2.5 VRMS), 1 kHz audio signal into the
microphone input.
(4)
Adjust the wideband deviation limit potentiometer, R30 on the main Rx/Tx module (see
Figure 2.4) to produce a ±4.45 kHz deviation. For TFM-138B only: Adjust the narrowband
deviation limit potentiometer, R76 on the main Rx/Tx module to produce a ±2.2 kHz
deviation. (All narrowband adjustments for TFM-138B only).
(5)
Verify that the deviation does not exceed ±5 kHz for wideband and ±2.5 kHz for
narrowband on the following frequencies: 138.000 MHz, 162.000 MHz and 174.000 MHz.
Re-adjust R30 or R76 as required, if the deviation exceeds ±5 kHz or ±2.5 kHz,
respectively.
(6)
Place top cover on transceiver chassis and secure all eight (8) screws.
