Ramsey Electronics COM3010 User Manual page 55

STEP-2 TUNING THE TRANSMITTER SIDE OF THE DUPLEXER (TX PASS)
1. The transmit side of the duplexer is tuned to reject noise at the receiver frequency.
2. Set up the COM 3010 to generate and monitor the repeater receiver frequency.
3. Attach the 50 Ohm load directly to the duplexer receiver port as shown in Figure-2.
4. Connect RF OUT to the duplexer antenna port as shown. This is done in order to inject
each signal for the test. -50dbm output is a good starting point.
5. Connect the RECEIVE IN to the duplexer transmitter port. The generator should be in the
RSSI mode.
6. Start tuning the cavity closest to the RECEIVE IN connection for minimum signal or
greatest notch. This will also be the noisiest signal (maximum negative RSSI indication).
Next do the same for the other cavities in line.
7. You may need to increase the Generator output level. Readjust all the in line cavities to
get the best tuning points as the rejection is increased.
Property of Ramsey Electronics, Inc.
8. You can determine the rejection in db by adding the generator db value to the RSSI
value. Example Generator - 40 dbm and Receiver RSSI -110 dbm = 70 db rejection. It
should be close to the manufacturers specifications.
9. The locking nuts on the Cavity tuning shafts should be hand tightened and the rejection
Do not reproduce or distribute.
tuning re-measured.
IMPORTANT: REPEAT STEPS 1 AND 2 UNTIL NO FURTHER IMPROVEMENT IN DUPLEXER
ISOLATION CAN BE ACHIEVED.
SET COM3010 TO REPEATER TX FREQ
TX PASS
TUNE TO NOTCH RX
50 OHM LOAD
TYPICAL TEST PROCEDURES
FIGURE-2
TX PASS – TRANSMITTER SIDE
TX PASS RX PASS
TUNE TO NOTCH TX
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RX PASS