Sailor RM2042 Technical Manual page 39

3 SERVICE
ADJUSTMENT OF TRIGGER LEVEL FOR CHANNEL-70 CARRIER DETECT
The channel-70 carrier detect circuit is constructed as a noise triggered squelch and the trigger level is
adjusted by the trimming resistor R36-3.
1. Apply an unmodulated carrier with the frequncy 156.525 MHz to the antenna terminal and adjust
the output level of the RF-signal generator to -126 dBm (EMF: -13 dB/µV).
2. Connect a multimeter or an oscilloscope to the output of the voltage comparator, pin 14 at U4.3-
3, for measuring the DC-voltage.
3. Turn the trimpot R36-3 counter clockwise until the output goes high.
4. Increase the RF-input level to -125 dBm (EMF: -12 dB/µV).
5. Now adjust R36-3 clockwise until the output goes low.
6. Increase the RF-input level to -122 dBm (EMF: -9 dB/µV) and control that the output goes high.
ADJUSTMENT OF TRIGGER LEVEL FOR VHF CARRIER DETECT
The VHF carrier detect circuit is identical to the corresponding carrier detect circuit for the build-in
channel-70 receiver and the trigger level is adjusted by the trimming resistor R93-3.
1. Connect the RM2042 to the VHF tranceiver by means of the 9 pole SUB-D connector.
2. Apply an unmodulated carrier with the frequncy 156.525 MHz to the antenna terminal at the
connected VHF tranceiver and adjust the output level of the RF-signal generator to -126 dBm
(EMF: -13 dB/µV).
3. Connect a multimeter or an oscilloscope to the output of the voltage comparator, pin 13 at U4.4-
3, for measuring the DC-voltage.
4. Turn the trimpot R93-3 counter clockwise until the output goes high.
5. Increase the RF-input level to -125 dBm (EMF: -12 dB/µV).
6. Now adjust R93-3 clockwise until the output goes low.
7. Increase the RF-input level to -122 dBm (EMF: -9 dB/µV) and control that the output goes high.
ADJUSTMENT OF 10V
The 10V power supply is used by the build-in channel-70 receiver and the FSK encoder/decoder.
1. Connect a voltmeter to the output of the 10V power regulator, pin 1 at U10-3.
2. Adjust the DC voltage to 10V ±10mV.
3.7 REPLACEMENT OF COMPONENTS
When replacing integreted circuits, transistors, diodes, resistors, capacitors and similar components you
must use a small "pencil" soldering iron with a maximum temperature of 300°C (572°F). The soildering
must be performed rapidly to avoid superheating and the use of a desoldering wire is recommended, as
otherwise there is a risk that both the components and the printed circuit will be spoiled.
3.8 REPLACEMENT OF MODULES
If a fault has been located to a single module, it may often be worth-while to replace it and then repair it
later on.
9403
RM2042
PAGE 3-9