Motorola ASTRO XTL 5000 Basic Service Manual page 83

Radio Alignment Procedures: Transmitter Alignments
4. Left-click the PTT Toggle button on the screen to enable transmission. The screen indicates
whether the radio is transmitting. Wait approximately 5 seconds until the voltage shown on R-
2670, or the deviation shown on the 8901 Analyzer, stabilizes.
5. Measure and record the AC voltage value from the R-2670 Analyzer or the deviation value
from the 8901 Analyzer.
6. Left-click the PTT Tone High button.
7. Adjust the softpot value until the measured deviation/voltage, when using the high tone, is
±
within
8. Repeat steps 3-7 for the remaining frequencies.
9. Left-click the Program All button on the screen to dekey the radio and save the tuned values.
10. Left-click the Close button on the screen to return to the Tuner Main Menu.
6.4.9 Tx Deviation Limit
NOTE: This alignment is required after replacing (or servicing) components on the transceiver board.
The Tx Deviation Limit alignment procedure limits the modulation of a baseband signal. It is used for
primary modulation limiting. 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.
This test can be done with either the R-2670 Communication Analyzer or the Agilent 8901
Modulation Analyzer. The method of choice is the R-2670 Analyzer.
• Initial setup 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 tuner
screen. Move the cursor to the "B/W" setting and select "WIDE
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."
• Initial setup using the 8901 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.
1. Select TX Deviation Limit from the Tuner Main Menu. The screen will indicate the transmit
frequencies to be used. See
6871769L01-A
1.5% of the value observed when using the low tone.
Figure 6-13 on page
±
100 kHz" on the soft key
6-18.
6-17
October 30, 2006