Verifying Receiver Circuitry (Digital-Capable Stations) - Motorola PDR 3500 Basic Service Manual

Verifying Receiver
Circuitry (Digital-
Capable Stations)
68P81093C75-O
Step 14. Steps 14 and 15 will test the effect of duplexer
quieting on receive sensitivity. Re-enable the
transmitter by holding down the Shift button again
and pressing the Access Disable button on the SCM.
The following lights should indicate that the station is
now operating as a repeater:
• Yellow Access Disable light stops flashing
• PA Full LED on the Exciter Module lights when
the station is receiving.
Step 15. Test the 12 dB SINAD sensitivity. Depending on the
duplexer frequency spacing, this level should be no
more than 1 to 2 dB greater than the Step 13 reading
(with the transmitter disabled). If the reading is greater
than 1 to 2 dB, the station transmit frequency does not
match the duplexer receive frequency. Use a different
frequency or replace the duplexer. (Field tuning of
duplexers is not recommended.)
Step 16. If the station is not digital-capable, the Verifying
Receiver Circuitry test procedure is complete. The
receiver circuitry is considered to be operating
properly if all displays and measurements are correct.
1. Remove the test equipment.
2. Restore the station to normal service.
3. Return to the troubleshooting flow chart to resume
the troubleshooting sequence.
If the station is digital-capable, continue with the
Digital Only portion of the Verifying Receiver
Circuitry test procedure.
Introduction
While most module faults can be detected by running the station
diagnostics provided by the RSS, the following procedure provides
a more traditional method of troubleshooting the receiver circuitry.
This procedure allows the service technician to make minor
adjustments and verify the proper operation of the station receive
circuitry, including:
• Receiver Module
• Power Supply Module
• 2.1 MHz Reference Oscillator Circuitry
• Receiver-related circuitry in the Station Control
Module (SCM)
September 27, 2000 9-21