Motorola ASTRO SPECTRA Service Manual page 93

Radio Alignment Procedure: ASTRO Digital Spectra and Digital Spectra Plus Tuner Software
This procedure needs to be performed at multiple frequencies to allow for proper alignment across
the entire RF band. The RF band is divided into frequency zones with a calibration point (value) in
each zone.
Proper alignment requires a modulation analyzer or meter with a frequency response to less than
10Hz modulating frequency. The modulation analyzer settings during this test should be set for
average deviation, a 15 kHz low-pass filter, no de-emphasis, and no high-pass filter, if these settings
are supported.
This test can be done with either the R-2670 Communication Analyzer or the 8901_ Series
Modulation Analyzer. The method of choice is the R-2670 analyzer.
1. Initial set up using the R-2670 Communication Analyzer:
- Connect a BNC cable between the "DEMOD OUT" port and the "VERT/SINAD DIST/DMM
COUNTER IN" port on the R-2670.
- Press the SPF key on the R-2670 to display the "SPECIAL FUNCTIONS MENU." Move the
cursor to "High Pass," and select 5 Hz on the soft key menu. Select 20 kHz for the "Low
Pass" setting.
- In the "RF Control" section of the R-2670, enter the frequency displayed on the RSS
screen. Move the cursor to the "B/W" setting and select "WIDE +/- 100 kHz" on the soft key
menu.
- Place the R-2670 cursor in the "Display" zone. Select "AC VOLTS" on the soft key menu.
Move the cursor to the "Range" setting and select "AUTO."
2. Initial set up using the 8901_ Series Modulation Analyzer:
- Press the FM MEASUREMENT button. (The "Error 03-input level too low" indication is
normal until an input signal is applied.)
- Simultaneously press the Peak – and Peak + buttons. Both LEDs on the buttons should
light.
- Press the 15 kHz LP filter key.
3. Select the TX Deviation Balance alignment screen. The screen will indicate the transmit
frequencies to be used. See
4. Left-click the desired frequency field (starting with the highest frequency shown).
5. Left-click the PTT Toggle button on the screen to make the radio transmit. The screen
indicates whether the radio is transmitting.
6881076C20-E
Figure 6-16 .
6-19
February 3, 2003