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No
Go to synthesizer
troubleshooting.
PA RF SECTION FAULT
No
Check CR6501, Q6506,
Q6501, L6503, L6502.
Check U6502, R6520,
No
L6519, L6504 ,L6505,
L6506,VR6501.
No
Replace U6501.
No
Check CR6502, CR6503,
CR6504, R6538, R6539,
R6537.
No
Check L6513, L6513,
C6543.
Replace Antenna
connector.
Troubleshooting Flow Chart
for Power Amplifier
8-6
Troubleshooting
Yes
No
Is PA control
at ~0V?
Is there 5V at
Is synt out
>2dBm?
PA_ENABLE?
Yes
there ~2V
Is RF at
at U0702-2
U6501
(PA_PWR_SET)
~2dBm?
Yes
Are voltages
Is there ~ OV at
at U6501*
U0701-7?
OK?
Yes
Is RF
at U6501
U0701-14
output ~24dBm?
at <4.5V?
Yes
Is RF after
Tx switch
at <4.5V?
at ~24dBm?
Yes
Is RF after
U0701-10
Harmonic Filter
at ~23dBm?
Yes
Faulty integrator.
Replace U0701.
START
No
Yes
Is Red light on?
Is control head
OK?
Yes
Yes
Is K9.1 OK?
Yes
Go to controller
troubleshooting.
No
PA LOGIC SECTION FAULT
Is
No
Faulty power setting DAC
or software
?
Yes
Faulty coupler.
No
Check CR6509, R6515,
CR6506, R6514, L6516,
R6512.
Yes
Is
Check R6519, U0701,
No
L6515, R0725, R0721,
R0722, R0723.
Yes
Faulty current sense
Is
No
mechanism. Check
U0701-1
R6520, U0701 DAC
(U0702-11).
Yes
Is
Faulty REF voltage.
No
Check R0251, R0252,
~4.6V?
U0251.
Yes
Go to
No
control head
troubleshooting.
Is there
No
No
Go to controller
5V at
troubleshooting.
K9.1 ENB?
Yes
Is there
No
Replace
9.3V at Q0741
Q0741 and Q0742.
or Q0742?
Yes
Go to
synthesizer
troubleshooting.
Levels were measured with an
RF probe in series with 0.5pF
capacitor.
*U6501 DC voltages:
Pins 3 and 4: A+-0.1V
Pin 2: 9.1V (during Tx only)
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