Troubleshooting
68P81096E17-E
39
09/30/05
Varactor-Tuned Preselector Tuning Procedure
The Receiver Module may contain a varactor-tuned preselector which
must be retuned whenever the Receiver Module CLN1211 replaced in the
field. The tuning procedure requires application of an RF signal into the
receiver and use of the RSS
Service
menu to set the high and low align-
ment values of the varactor-tuned preselector. Either the Received Signal
Strength Indicator (RSSI) value (if available) or SINAD is read and peaked
by changing the preselector alignment values via the RSS. The alignment
values 132.025 MHz, 146.025 MHz, 160.025 MHz, and 173.975.025 MHz
are stored in memory (within the Station Control Module).
These four alignment values are the only information required to interpo-
late the tuning voltage of the preselector to any frequency within the 132
to 174 MHz band. To retune this preselector, perform the Varactor-Tuned
Preselector alignment procedure located in the RSS
Service
menu Online
Help facility.
The RSSI can be monitored at pin C11 of the Systems connector (J5) on the
station backplane (refer to Figure 10 for the location).
Figure 9. Location of Tuning Screws and Cavity Probe Holes
Preselector
Assembly
To antenna
connector
To Receiver
Module
Tuning
Cavities
HI
H2
H3
Tuning
Screws
H4
5
4
3
2
1
Note
Summary of Contents for MTR2000 T5544
Page 56: ...Description THIS PAGE INTENTIONALLY LEFT BLANK 68P81096E36 H 13 06 28 05 ...
Page 160: ...VHF Receiver Module 6 68P81096E19 B 09 30 05 THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 167: ...VHF Exciter Module 6 68P81096E22 C 09 30 05 THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 259: ...DLN6622 500W Power Supply Module 6 68P81011Y31 O 03 10 06 THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 271: ...DLN6624 250W Power Supply Module 6 68P81011Y29 O 03 10 06 THIS PAGE INTENTIONALLY LEFT BLANK ...