How To Verify Vhf Duplexer Isolation; Vhf Duplexer Post Tuning Checks; Tuning A Uhf Duplexer - Motorola GTR 8000 Manual

5.9.4.7.1 How To Verify VHF Duplexer Isolation

Procedure Steps
1 Connect test equipment as shown in
2 Observe and note the level in dBm as shown on the service monitor.
Connect the test equipment to the duplexer as shown in
3
4 Observe and note the level in dBm as shown on the service monitor. (If no number is displayed, consider
isolation to be greater than 105 dB, which exceeds the specification.)
5 Subtract the absolute number noted in step 4 from the number noted in step 2. The difference should be
less than 75 dB to meet specification for Isolation.
Repeat steps 1 through 5 for Low-Pass/High-Notch cavities with the following exceptions:
6
a. Set service monitor tor Rx or Tx frequency, whichever is HIGHER
b. Connect service monitor to Low Pass duplexer input (cavity #1)
c. Connect terminator to cavity #6.

5.9.4.8 VHF Duplexer Post Tuning Checks

Procedure Steps
1 Make sure all locking screws are tight. Re-install dust covers on all trimmer capacitors.
Make sure all tuning rod locking screws (6) are tight.
2

5.9.5 Tuning a UHF Duplexer

The following procedures are most easily performed with the duplexer module removed from the rack or cabinet. Be
sure to make note of the transmit and receive frequencies for the particular base radio before beginning.
If the duplexer module is tuned according to instructions and does not meet specifications for return loss, insertion
loss, and/or isolation, you must return the duplexer for repair.
6871022P86-A - November 2012
Figure 5-10.
Figure

5.9.4.7.1 How To Verify VHF Duplexer Isolation

5-11.
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