Rx If-Poor Sinad Or No Audio (136-174 Mhz); Figure 5-5. Rx If-Poor Sinad Or No Audio (136-174 Mhz) - Motorola ASTRO XTL 1500 Detailed Service Manual

Digtal, vhf/uhf range 1/uhf range 2/700–800 mhz
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5-14
5.6.3
RX IF—Poor SINAD or No Audio (136–174 MHz)
easure the IF
signal level
on C3414
Level
is -4/-13dBm
referenced to the
RF input
level?
Yes
easure the IF
signal level
on C3408
Level
is +16/+5dB
relative to the RF
input level?
No
Refer to
troubleshooting
flow digram for
Receiver Back End
Figure 5-5. RX IF—Poor SINAD or No Audio (136–174 MHz)
June 15, 2005
(Std/Pre mode)
No
(Std/Pre mode)
Yes
Refer to
troubleshooting
flow diagram for
Receiver Front End
easure the DC
Bias voltage level
on transistor
Q3401
Voltage
level of
>~5.0V at Q3401
?
Yes
easure 0.7V on
LNA at Q3401
Voltage
level of
0.7V at Q3401
?
Yes
Inspect crystals and
matching networks for
missing components
and/or soldering defects
Troubleshooting Charts: Flowcharts
Inspect biasing
No
components
No
Replace
Q3401
AEPF-27809-O_VHF
6815854H01-A

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