120
MDS™ Master Station
MDS 05-6399A01, Rev. F
Figure 8-2. 900 MHz Bandpass Duplexer
(Adjustment generally not required for transmit changes up to 500 kHz)
8.5 Testing and Removing an Internal Duplexer
Testing
If you suspect that the internal duplexer is not functioning properly, perform the following steps
to determine if requires replacement:
1.
Measure the RF power out of the antenna jack.
-
If the power registers approxi37 dBm (5 watts), the internal duplexer is
probably functioning correctly (see
Table 9-1. dBm–Volts–Watts Conversion
Chart
for dBm-volts-watts conversion chart).
-
If the power registers significantly less than +37 dBm, proceed with Step 2.
2.
Locate the TX SMA connection on the front of the duplexer tray.
3.
Using an adapter, connect the RF power meter to the SMA Cable on the front of the unit
•
If the power reg39 dBm, the radio board is functioning correctly.
•
If the power registers less than +39 dBm, proceed with Step 4.
4.
Use the front panel to switch to the alternate transmitter and again measure the RF power
output.
•
If the alternate transmitter reg39 dBm, the internal duplexer probably needs
replacing.
5.
Before replacing the duplexer, verify that the highest or lowest frequencies marked on the
duplexer are the same as radio’s transmit and receive frequencies or within the nominal
operating range: 100 kHz for 400 MHz radios, and 500 kHz for 900 MHz radios.
Removing the Internal Duplexer
To remove the internal duplexer, follow these steps:
Disconnect the antenna cables from the back of the chassis.
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