Closed Loop Power Test - Motorola MTH500 Service Manual

Troubleshooting
Replace LNODCT, perform
Open Loop Power test and
Close Loop Power test.
3 - 20

Closed Loop Power Test

This test should be carried out only after the successful completion of the previous tests.
Check the elements: coupler U806, R815, R818,
R825, R826, C817. Replace if faulty and repeat the
Close Loop test.
No
OK
Measure the LO power on pin 24 MVCO
of the LNODCT U803 (800-400 mVp-p
(single ended) swing into a 50Ohm load).
Yes
Check R838, C814 replace if faulty, repeat
Close Loop Power test. If the problem still
exists replace LNODCT U803 and repeat
Open Loop Power test and Close Loop
Power test.
Tune the radio on PATS.
Is the
radio close loop
No
output power <28dBm
or >31 dBm?
Yes
Does the
close loop power
problem still
exists?
Yes
Is the LO power OK?
No
OK
68P02963C70-O