User's Manual

6881094C31-C October 14, 2003
Troubleshooting Charts: TX RF (VHF) 5-29
TX RF (VHF)—Page 2
MAEPF-27420-B
RAWB+
about
7.2 Vdc?
Measure
RAWB+
at Q107-drain
No
No
No
Ye s
Ye s
Ye s
Check
continuity
V.gate
about 2 to
3 Vdc?
Check
continuity
DC bias is OK,
control is OK,
RFIN is OK,
PA has low gain
Replace
Q107
No
Ye s
Measure RF
level at
pin 6 of Q107
Is
unit
VHF?
No
Ye s
Remove SH101
and check for
parts off pad
Level
about
+35 dBm?
Replace U102.
For VHF, check under
SH101. if all parts soldered,
replace U102.
Measure
gate bias
at L108
RAWB+
about
7.2 Vdc?
Measure
RAWB+
at U102-6
No
No
Ye s
Ye s
TX7V
about
7.2 Vdc?
Check
continuity
Measure
Vgate at TP111,
normally 4 to
5.5 Vdc
Measure
TX7V at
U102-14
DC bias is OK,
control is OK,
RFIN is OK, driver
has low gain
Vgate
> 4 Vdc?
2
1
3
4