Fluke 6080A - Coarse Loop Tests 6-29.; Sub-Synthesizer Tests 6-30.; Sum Loop Tests 6-31.

TROUBLESHOOTING AND REPAIR
Coarse Loop Tests 6-29.
The first three Coarse Loop Tests (see Table 6-8) program a frequency in each of the
three Coarse Loop VCO bands with the normal steering DAC value and expect the
loop to remain locked. The fourth test programs a valid frequency but the steering
DAC is set to zero. This should force the loop to unlock.
Table 6-8. Coarse Loop Tests
Sub-Synthesizer Tests 6-30.
The first Sub-Synthesizer Test (see Table 6-9) programs a valid frequency near the
center of the Sub-Synthesizer range and expects the Sub-Synthesizer to remain locked.
The next two tests force the Sub-Synthesizer to frequencies outside of its normal
operating range and expect it to go unlocked.
Table 6-9. Sub-Synthesizer Tests
Sum Loop Tests 6-31.
The first four sum loop tests (see Table 6-10) program a frequency in each of the four
Sum Loop VCO bands with the normal steering DAC value and expect that the loop
will remain locked. The fifth test programs a valid frequency but the steering DAC is
set to zero. This should force the loop to unlock.
The next two tests program 4 MHz of FM deviation at a low and a high modulation
rate and expect the sum loop to remain locked.
Table 6-10. Sum Loop Tests
6-11
CODE
320
321
322
323
COARSE LOOP
FREQUENCY
640 MHz
768 MHz
896 MHz
640 MHz
COARSE STEER DAC
Normal
Normal
Normal
0
EXPECTED STATE
OF COARSE LOOP
Locked
Locked
Locked
Unlocked
CODE
324
325
326
RF FREQUENCY
804.000000 MHz
800.000000 MHz
807.999999 MHz
SUB-SYNTHESIZER
FREQUENCY
240 MHz
120 MHz
350 MHz
EXPECTED STATE
OF SUB-SYNTHESIZER
Locked
Unlocked
Unlocked
CODE
327
328
329
330
331
332
333
FREQUENCY
550 MHz
700 MHz
830 MHz
975 MHz
550 MHz
800 MHz
800 MHz
SUM STEER
DAC
Normal
Normal
Normal
Normal
0
Normal
Normal
INT FM
Off
Off
Off
Off
Off
On
On
FM DEV
4 MHz
4 MHz
MOD
FREQ
50 kHz
63 Hz
EXPECTED STATE
OF SUM LOOP
Locked
Locked
Locked
Locked
Unlocked
Locked
Locked