Motorola VRS750, Service Manual

Page: 71 / 104

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d. Switch off the VRS Communications Analyzer RF.
6. Take the VRS out of test mode:
a. Turn off mobile control head and set the dipswitch S1 pins 1,
2, 3, and 4 to ON.
b. Turn on the mobile control head and re-enable the VRS.
7. Tuning is complete.
Transceiver Board Tuning
Procedure
The transceiver board can be tuned using the Global Tuner when the
VRS750 is in ATE Test Mode. Connect the VRS750 to the test box
(RLN5394A) instead of the ASTRO Spectra mobile using the VRS750
ATE Cable (3080384N02) as shown in Figure 33. Before applying
power, set dipswitch S1 pin 1 to ON and pins 2, 3, and 4 to OFF. This
configures the VRS750 for ATE Test Mode. Make the appropriate
connections to the VRS750 test box for power and audio. Once this is
complete the VRS750 can be tested and tuned using the Global Tuner.
Front End Filter Tuning
NOTE: Tuning is normally not required for VHF radios. It
should only be performed if a radio has poor
sensitivity. VHF radios are only tuned at one softpot
frequency (F3: The values for the untuned frequencies
are determined by adding the offset, calculated by
subtracting the default softpot value for frequency F3
from the tuned softpot value for frequency F3. The
default softpot values are listed in Table 9.)
Figure 33. ATE Test Mode Configuration
VRS750
VRS750
TEST BOX
(RLN5394A)
VRS750
PROG. CABLE
RX AUDIO
AND EXT MIC
CONNECTORS
SRIB
DC SUPPLY
VRS750 ATE CABLE
(3080384N02)
CONNECT TO THE PCs
COM PORT