Rx Rf; Rx Rf—Page 3 - Motorola ASTRO XTS 5000 Detailed Service Manual

6-22
6.23 RX RF—Page 3
2
Measure RF levels
at TP13 and D401-3.
Compute filter loss
Loss < 3 db?
Yes
Measure RF levels
at D401-3 and TP402.
Compute LNA gain
Gain
about
+12 dB?
Yes
Measure RF levels
at TP402 and TP403.
Compute FL402 loss
Loss
< 3 dB?
Yes
Measure RF levels
at TP403 and TP404.
Compute mixer gain
Mixer
gain about
4 dB?
Yes
April 15, 2002
No
6
No
Check
LNA
No
8
No Check
mixer
Troubleshooting Charts: RX RF—Page 3
3
Measure
control voltage
at TP502
Fvco
No
< 107.4 MHz?
Yes
TP502 No
5
= 5 Vdc?
Yes
Remove SH501,
inspect 2nd
LO VCO
Visual
No
examination
OK?
Yes
Replace
Varactor D550
Measure RF levels
at TP404 and TP12.
Compute IF filter loss
No
Loss
< 3 dB?
Yes
No problem
found
TP502 TP501
(Vdc) (MHz)
Fvco
0.00 101.0
1.85 107.4
4.30 111.9
5.00 113.0
No
TP502
5
= 0 Vdc?
Yes
Repair
defects
7
MAEPF-27472-O
68P81094C31-O