Sailor RM2042, Technical Manual, Page: 36 / 106

3 SERVICE RM2042
CHECK OF TX AF DISTORTION
The TX AF distortion is controlled by measuring the distortion of the TX AF signal at pin 4 in the 9 pole
SUB-D connector P2-1 at the interface module.
NOTE! To perform this test, it is necessary to change the operation mode of the RM2042 from user to
service mode. This change of operation mode is only allowed for trained technicians and the information
of how to do it is therefore only included in the DSC-VHF INSTALLATION GUIDE.
1. Connect a LF-distortion meter to the output of the used TX AF amplifier.
Unbalanced TX AF amplifier: use pin 4 (TX AF+) and pin 2 (GND) in P2-1.
Balanced TX AF amplifier: use pin 4 (TX AF+) and pin 8 (TX AF-) in P2-1.
2. Change the operation mode of the RM2042 from user to service mode.
3. Start the transmission of a mark signal by pressing ‘FUNC’ and selecting ‘Test’ and ‘mark’ in the
display.
4. Control that the distortion is less than 5%.
5. Start the transmission of a space signal.
6. Control that the distortion is less than 5%.
7. Change the operation mode of the RM2042 back to user mode.
3.6 ADJUSTMENT PROCEDURE
This section contains the adjustment procedures for all adjustable components in the RM2042.
3.6.1 ADJUSTMENT OF INTERFACE (MODULE 1)
ADJUSTMENT OF UNBALANCED TX AF AMPLIFIER
When the RM2042 is operating as an automatic system together with one of our VHF tranceiver, the TX
AF output is delivered as an unbalanced signal adjusted in level to give a modulation index of 2, measured
at the transmitter output. During the adjustment, the RM2042 must be connected to the same VHF
tranceiver as it is going to be installed with. This demand is motivated by the fact, that the microphone
input sensitivity may vary from one tranceiver to an other.
The unbalanced signal is amplified by the operational amplifier U3.3 and the output level is adjusted by
means of the trimpot R22-1.
NOTE! To perform this test, it is necessary to change the operation mode of the RM2042 and the VHF
tranceiver from user to service mode. This change of operation mode is only allowed for trained
technicians and the information of how to do it is therefore only included in the DSC-VHF INSTALLATION
GUIDE.
1. Connect the RM2042 to the VHF tranceiver by means of the 9 pole SUB-D connector P2-1 at the
interface module.
2. Reduce the output RF-power from the VHF tranceiver to 1 Watt.
3. Connect a modulation meter through an attenuator to the antenne terminal at the VHF tranceiver.
NOTE !
To protect the modulation meter from damages caused by the large output
voltage, it is necessary to use an attenuator of about 30dB.
4. Change the operation mode of the RT2047 or the RT2048 from user to service mode. Select a DSC
VHF channel different from channel 70 and change the operation mode back to user mode.
5. Change the operation mode of the RM2042 from user to service mode.
6. Turn the switch S1-1 at the interface (module 1) into the position: ‘1’.
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