Motorola MTP700 Detailed Service Manual page 199

TRANSCEIVER 800 MHz
Open Loop Power Test
This test should be carried out only after the successful completion of the previous tests.
Measure the Open
Loop Power by
using PATS.
Is the output
power less than
28dBm?
Yes
Is the output
Are voltages 2.775V_RF,
5V_RF, RAW_B+_RF and
2.5V_TX supplied to the
Transmitter components?
Yes
Is there -2.5Vdc of
ANT_EN signal on Q806
pin (or C830) during TX
slot?
No
Using a Power Probe, measure
RF power at the ldmos driver
U800 input (pin 16).
Is power <-5dBm?
Yes
Using a Power Probe, measure
RF power at the LNODCT
U803 outputs (pins 51, 52).
MTP700 Portable Radio / Detailed Service Manual
No Is the output
power above
31dBm?
No
Check the battery
regulators Q801, Q805,
U907, Q806, U802
No
elements on 2.5V_TX
lines. Replace if faulty.
Check voltage across
R816 and R805. Perform
the Open Loop Power test
again.
Check E810. Perform
Yes
REDCAP2 test.
Repeat Open Loop
Power test.
Using a Power Probe test TX line up
(starting from RF ldmos driver U800
output: pins 6, 7) by measuring output
power after every component of
No
Transmitter till Antenna.
It should be as specified in the spread
sheet, otherwise replace the damaged
components.
Perform the Open Loop Power test again.
A
Yes
Is the radio in
oscillation?
Yes
Check RF PA U800, Q800.
Isolator FL801, Coupler U806.
Components:E808, C924, C926,
C951, C964, L917, L900, L901, C907,
C908, C909, C961, C910, C962.
Check the bias voltages on
pin 16 of U800 and pin 7 of
No
U802. Check L917, C950,
C958, C921.
Perform the Open Loop
Power test again.
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