Installation manual
XR6/XR3 Installation Manual Commissioning tasks
Issue 3.0 2009-07-15 Page 11-5
Modulation checks
Verify that the RF output is appropriately modulated when audio is applied:
23. Connect an appropriate modulation monitor to the remote interface PWB’s RF MONITOR
connector (J8). The modulation monitor should have an impedance of 50 Ω. to obtain
accurate readings.
24. Verify that forward power is selected for display on the RF KILOWATTS meter.
25. Select the highest preset RF power level and verify that the RF output, displayed on the RF
KILOWATTS
meter, is the desired forward power level.
26. Verify that an audio signal generator is connected between TB2-1 (+) and TB2-3 (-) on the
remote interface PWB, and that its output is preset to 1,000 Hz at a zero output level (turned
off).
27. Turn off the audio signal generator and increase the output level of the audio signal
generator until a modulation depth of 100% is attained, as indicated on the modulation
monitor. The audio signal generator's output level should be +10 dBm.
28. Verify that the RF output's modulation envelope is acceptable.
29. If the program audio can be set to +10 dBm when 100% modulation is required, it is
recommended the AUDIO GAIN potentiometer on the interphase PDM driver PWBs be left
at the factory setting.
30. If the program audio cannot be set to +10 dBm when 100% modulation is required, the
AUDIO GAIN potentiometer on the remote interface PWB must be reset as follows:
– Determine the program audio level (in dBm) that will be applied when 100% modulation
is expected. (It must be between 0 dBm and +12 dBm.)
– Set the audio signal generator's output to the level that will be applied by the program
audio when 100% modulation is expected.
– Adjust the
AUDIO GAIN potentiometer on the remote interface PWB for 100%
modulation, as indicated on the modulation monitor.
31. Set the output level of the audio signal generator to zero (turned off).
32. Turn off the RF power stage: press and release the RF OFF switch. The RF OFF lamp will turn
on and the
RF ON lamp will turn off.