TM 11-6625-2398-15-3
(1) On the signal generator, set the
Hybrid attenuator settings
Variable attenuator settings
MEGACYCLES dial to 1030 with the frequency control
12.0
121.1ldB
knob. Set the function switch to 1000 , the MOD. UP-
15.0
151.1dB
NORMAL-DOWN to NORMAL, adjust the MOD. LEVEL
20.0
201.1dB
control for a reading of 50 on the PERCENT
25.0
251.2dB
MODULATION meter, and set the attenuator to 0dB
(outer scale). Turn on the signal generator and allow a
(13) Correct the hybrid attenuator calibration tag
minimum of 20 minutes warm-up period before
markings for 1090MHz, if incorrect.
proceeding.
(14) Reset the signal generator MEGACYCLES
(2) With the METER SCALE set to NORMAL, and
dial to 1030 and repeat steps (3) through (11) above.
INPUT SELECTOR set to XTAL200KΩ, turn on the
The ATTENUATOR DB control of the variable
SWR indicator and allow a minimum of 10 minutes
attenuator must indicate 0 +3.0, -0.0dB.
warm-up period before proceeding.
(15) Repeat step (12) for the readings recorded in
(3) Terminate and connect the hybrid attenuator
step (14), with the following limits:
as directed in A of figure 6-5 (RF IN/OUT jack VSWR).
Hybrid attenuator settings
Variable attenuator settings
(4) Insert the crystal in the rf detector of the
3.0
33.0, -2.0dB
slotted line and turn the probe depth control fully
6.0
63.0, -2.0dB
clockwise. Adjust the slotted line tuning knob for a
9.0
93.0, -2.0dB
maximum indication on the meter of the SWR indicator.
12.0
123.0, -2.0dB
15.0
153.0, -2.0dB
20.0
203.0, -2.0dB
(5) Adjust the signal generator OUTPUT LEVEL
25.0
253.0, -2.0dB
control for a centered reading on the meter of the SWR
indicator.
(16) Correct the hybrid attenuator calibration tag
markings for 1(0O0MHz, if incorrect.
(6) Move the carriage of the slotted line, with the
drive control, to obtain a peak (maximum) meter reading
6-1 1. Hybrid Attenuator VSWR Measurements
on the SWR indicator.
(7) Decrease the slotted line probe depth (turn
a. Trust Equipment and Materials. The following test
control counterclockwise), while adjusting the VERNIER
equipment and materials are required:
GAIN control and RANGE switch of the SWR indicator,
to the minimum probe depth required to provide full
Signal Generator SG-340/G
scale deflection on the meter of the SWR indicator
(consistent with a usable meter reading, free of noise
Slotted Line IM-92/U
and jitter).
SWR Indicator AN/UPM-108A
(8) Readjust the drive control knob of the slotted
Low Pass Filter HP-360C
line for the peak (maximum) reading on the standing
wave ratio indicator meter. Adjust the VERNIER GAIN
Adapter UG-606/U
control and RANGE switch of the SWR indicator for a
meter reading of exactly 1 on the SWR scale.
Fixed Attenuator AT1/AT2
Terminations AT3/AT4 (2)
(9) Move the carriage of the slotted line, with the
drive knob, to obtain a null (minimum) reading on the
Adapter CP7/CP8 (2)
meter of the SWR indicator. Read the voltage standing
wave ratio on the
Cables W14/W15 (2)
Cable A1W3.
b. Procedure.
6-12
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