Yes
No
7
Is current less
than 350 mA?
Use a spectrum
analyzer and high-
impedance RF probe.
Measure RF_IN_1 at
C1601.
Is the frequency
correct?
Is the power
level about 3
dBm?
Is the power
appoximately 37
dBm?
See FGU
troubleshooting
charts.
Check U1110 and
see FGU
troubleshooting
charts.
Measure power at
C1625.
Replace U1602.
Measure power at
C1822, and calculate
harmonic filter loss.
Is the loss less
than 1 dB?
Repair any issues
with 1400 series parts
in the harmonic filter.
PA and harmonic
filter are functioning
properly.
Measure TX current
at UHF1 test
frequencies.
If power issue is not
resolved.
4
No
No
No
Yes
Yes
Yes
Yes
Yes
No
Yes
Replace Q1601
Is current
approximately
500 mA?
Is current
greater than or
close to 2A?
No
Yes
Is voltage
approximate 6 V?
Measure DC voltage
at pin 4 of U1601
Measure voltage at
pin 5 of U1601
Is voltage
approximate 7 V?
Replace U1601
Measure voltage at
pin 3 of Q1101
(UHF1/7800) or
pin 3 of Q1102
(UHF1/VHF) or
pin 3 of Q1101
(UHF1/UHF2).
Measure voltage at
pin 1 of Q1101 (UHF1/7800) or
pin 1 of Q1102 (UHF1/VHF) or
pin 1 of Q1101 (UHF1/UHF2).
Measure DC voltage
at pin 4 of U1601
Is voltage
near 7.5 V
Is voltage
near 3 V
Trace voltages and check
for solderability issues on
R1102, Q1101, and Q1103.
Replace parts as necessary.
Check E1101 for
solderability issues
and replace as
necessary.
Check L1603 for
solderability issues
and replace as
necessary.
Check L1606 under
sheild SH10 for
solderability issues
and replace as
necessary.
With the radio in RX
mode, measure the
DC voltage on
both pins of L1603
Is voltage
near 7.5 V on
both sides?
Is there 7.5 V
on C1608?
With the radio in RX mode,
measure the DC voltage
on the drain of Q1601.
Measure voltage at
pins 2 and 3
(UHF1/7800) or
pins 7 and 6
(UHF1/VHF) of U1119 or
pin 2 and 3
(UHF1/UHF2) should be
5 V and 2.775 V
respectively.
Measure voltage at
pin 1 of Q1101 (UHF1/7800) or
pin 1 of Q1102 (UHF1/VHF) or
pin 1 of Q1101 (UHF1/UHF2).
With the radio in RX mode,
measure the resistance
on the node shared by
C1616 and R1605.
Is the resistance
near 9.4k
Ohms?
Check resistors R1601,
R1602, R1603, R1604, and
R1605 for resistance and
solderability issues and
replace as necessary.
If resistance is very low, in the
100's of ohms,and there are no
issues with the resistors then
there is a gate short on the PA.
Clear short or replace Q1601.
In TX mode, measure
the voltage on pin 4
of U1601.
Is the voltage
near 6 V?
Is the TX current
between 300
and 900 mA?
The PA is likely
damaged. Replace
Q1601.
Is the TX current
above 900 mA?
Lift shield SH10 and check
for solderability or part
issues on all 900 series
parts. Replace parts as
necessary.
If no issues found, lift shield
SH13 and check for solderability
or part issues on all 1200 series
parts. Replace parts as
necessary.
4
Is TX current just
above standby
current?
If power issue is not
resolved.
The PA and Driver are likely
damaged. Replace Q1601
and U1602.
Is the voltage
below 4 V?
8
8
If the voltage is between 4 and 5.5 V then
the control loop should be working and
power should be available. Check the
coaxial cables and surface mounted
coaxial connectors
Are the
connections
OK?
3
Replace cables, or
connectors J101 or
J102.
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Is voltage
near 7.5 V?
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
No
Yes
Is voltage
approximate 0 V?
Replace
Q1103 (UHF1/7800) or
Q1104 (UHF1/VHF) or
Q1103 (UHF1/UHF2).
No
No
Is voltage
greater than 1.5 V?
Measure voltage at
pins 2 and 3 (UHF1/7800) or
pins 7 and 6 ( UHF1/VHF) or
pins 2 & 3 (UHF1/UHF2) of U1119
No
Are
pins 2 and 3,
or pins 7 and 6,
close to 5V and 2.775V
respectively?
Yes
Replace Q1101
(UHF1/7800) or
Q1102 (UHF1/VHF) or
Q1101 (UHF/UHF2).
Yes
Replace
U1119
Yes
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