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Peak-to-Average Ratio (AN/USM-485 AND 4935A Options 002 and 003 Only)
Figure 4. Transmitter A14 board - component locations.

Calibration Procedure For Transmission Impairment Test Set An/Usm-485 And Model 4935A With Options 001, 002, And 003 Page Navigation
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TB 9-6625-2151-24
(4) Press  , STEP UP, STEP DOWN, and
keys until TI right display indicates
1300 Hz. Adjust OUTPUT LEVEL control until left display indicates 0.0 dBm.
(5) Connect oscilloscope CHAN 1 to TP 15 pin 2 (fig. 1).
(6) Connect oscilloscope CHAN 2 to TP 15 pin 7 (fig. 1).
(7) Set oscilloscope controls as necessary to measure phase difference between
signals on CHAN 1 and CHAN 2.
(8) Adjust R153 PAR PHASE 1 (fig. 1) to obtain a 0 degree phase difference
indication on oscilloscope (R).
(9) Connect oscilloscope CHAN 1 to TP15 pin 8 (fig. 1).
(10) Adjust R175 PAR PHASE 2 (fig. 1) to obtain a 0 degree phase difference
indication on oscilloscope (R).
(11) Adjust R186 PAR DET (fig. 1) until TI right display indicates 100 (R).
14. Power Supply
NOTE
Do not perform power supply check if all other parameters are
within tolerance.
a. Performance Check
(1) Connect multimeter Input HI to JU+5 (fig. 4) and LO to ground. If multimeter
does not indicate between 4.8 and 5.2 V dc, perform b (l) below.
(2) Connect multimeter Input HI to JU+14 (fig. 4). If multimeter does not indicate
between 13.8 and 14.2 V dc, perform b (2) below.
(3) Connect multimeter Input LO to JU-14 (fig. 4) and HI to ground. Multimeter
will indicate between -13.75 and -14.25 V.
b. Adjustments
(1) Adjust R42 +5V ADJ (fig. 4) for a +5 V dc indication on multimeter.
(2) Adjust R31 +14V ADJ (fig. 4) for a +14 V dc indication on multimeter.
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