Motorola ASTRO XTS 5000 Detailed Service Manual page 63

Troubleshooting Charts: RX RF
5.14 RX RF—Page 1
Poor RX
sensitivity or
no RX audio
Inject a standard FM test signal
into the antenna port. Use CPS to
ensure that attenuator feature is
disabled. Use a spectrum analyzer
and high-impedance RF probe to
measure the IF signal at TP12
(700-800) or TP15 (VHF) on side 2
Frequency OK?
VHF: 44.85 MHz
UHF: 73.35 MHz
700-800: 109.65 MHz
IF
level about
-38 dBm?
Measure RF
input level
at TP02
RF level
about
-47 dBm?
Measure RF levels at TP02
and TP13 (UHF & 700-800)
or TP401 (VHF),
compute SW_FL loss
SW_FL
loss < 2 dB?
2
6881094C31-C
3 kHz FM deviation,
1 kHz rate, -47 dBm
No Check
RXLO
Yes
Yes
1
No
Inspect coaxial
No
antenna connector
and cable assembly
Yes
Check
No
SW_FL
Yes
Visual
No
inspection
OK?
Yes
Remove cable
assembly, measure
insertion loss
No
Loss
< 0.2 db?
Yes
Bad antenna connector.
Replace chassis
(connector is not
serviceable)
5-23
Replace
bad part
Replace
cable assembly
MAEPF-27470-B
October 14, 2003