TECHNISONIC INDUSTRIES LIMITED
www.til.ca
TFM-550 Installation & Operating Instructions
TiL 99RE262 Rev A Issue 9
3-8
3.9 TRANSMITTER POWER ADJUSTMENTS
The transmitter power is adjusted to a maximum of 10 watts in high power mode, and 1
watt in low power mode over the transceiver operating bandwidth at the factory. If
transmitter RF power readjustment is required, perform as follows:
1.
Select the band that you wish to adjust on the band select switch.
2.
Connect an RF through-line watt meter to the appropriate antenna connector. Set the
operating frequency to 156.000 MHz for VHF or 457.000 MHz for UHF and key the
transmitter.
3.
In low power mode, set the low power adjustment potentiometer on the left side of the
chassis to produce 1.0 watt of RF output power (See Figure 3.4).
4.
In high power mode, set high power adjustment potentiometer on the left side of the
chassis to produce 9.5 watts of RF output power.
5.
Verify that the RF output power is between 9 and 10 watts on 138.000 MHz, and
174.000 MHz for VHF or 403.000 MHz, and 512.000 MHz for UHF.
3.10 TRANSMITTER MICROPHONE 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 microphone level potentiometer (Mic Level 1) through the access hole located
on the right side of the chassis (see Figure 3.5) to produce a 2.7 kHz deviation.
4.
Verify that the deviation is at least 2.3 kHz on the following frequencies: 138.000 MHz,
162.000 MHz and 174.000 MHz.
5.
For UHF, perform the same procedure using the Mic Level 2 pot on the left side of the
transceiver and use the following frequencies: 403.000 MHz, 457.000 MHz and
512.000 MHz.
3.11 SQUELCH ADJUSTMENT
The squelch on all receivers is factory set to open at approximately 22 dB SINAD. This
adjustment can be made or altered to suit local conditions as follows:
1.
Set the receiver to 157.000 MHz for VHF, 457.000 MHz for UHF or 41 MHz for VHF
Low band. Connect a signal generator to the antenna input of the desired band.
2.
Set the signal generator to produce a ±3 kHz deviation with a 1 kHz tone on 157.000
MHz, 457.000 MHz or 41.000 MHz. Increase the signal generator RF level from 0.1 uV
until the squelch indicator LED is on. Verify the squelch opens at the desired level.
3.
If not, re-adjust receiver squelch potentiometer through the access hole located on the
bottom of the transceiver chassis (see Figure 3.5).
Summary of Contents for TFM-550
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