TB 9-5985-313-40
a. Performance Check
(1) Set signal generator output to off and RF power amplifier output to minimum.
(2) Adjust each power bridge divider dials for a null on OUTPUT VOLTAGE
meter. The meter pointer does not have to be on ZERO, only stopped on scale. Some drift
may be noticed after null is obtained.
(3) Set function switch on each power bridge to RVG (fully ccw).
(4) Measure voltage at RVG terminals of each power bridge, using multimeter.
NOTE
Minimize time expended between measurements in (4) above
and (9) below.
(5) Record voltage at bridge 1 as V2 and bridge 2 as V1.
(7) Adjust RF power amplifier controls for approximately 50 W forward power as
shown on RF power meter.
(8) Set V-REM-'V switch on each power bridge to 'V.
(9) Measure voltage at RVG terminals on each bridge, using multimeter. Record
voltage at bridge 1 as 'V2 and at bridge 2 as 'V1.
(10) Substitute values recorded in (5) and (9) above in the following formula and
solve for K0.
KO = (2V1 - 'V1) ' V1 K1
(2V2 - 'V2) ' V2
KO = Output calibration factor of TI at the applicable frequency.
K1 = Input calibration factor of directional coupler at the applicable frequency as listed on test report.
(11) Repeat (1) through (10) above for each applicable TI frequency.
(12) Set RF power amplifier and signal generator outputs to minimum. Deenergize
each power bridge.
(13) Disconnect thermistor mounts from each power bridge and reconnect them to
opposite power bridges.
(14) Energize each power bridge, wait 3 minutes, and repeat (2) through (11) above.
Remember that power bridges 1 and 2 are reversed.
(15) Determine average of the four values calculated for K0 and record average as
the TI's output calibration factor for the applicable frequency.
b. Adjustments. No adjustment can be made.
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