TM 11-6625-2398-15-3
6-10.
Hybrid Attenuator ATTENUATOR Dial
NOTE
Calibration
Check that OUTPUT VOLTS meter indication
is exactly on the SET LEVEL mark with the
a. Test Equipment and Materials. The following test
attenuator set to OdB (outer scale). Readjust
equipment and materials are required:
the OUTPUT LEVEL control knob if required.
Signal Generator SG-340/G
(5) On the signal generator, set the function switch
to 1000~, the MOD. UP-NORMAL-DOWN switch to
Variable Attenuator, Alfred Electronics
NORMAL and adjust the MOD. LEVEL control for a
Model E101
reading of 50 on the PERCENT MODULATION meter.
Set the hybrid attenuator ATTENUATOR control to 0
SWR Indicator AN/UPM-108A
(zero). Adjust the SWR indicator VERNIER GAIN
control and the RANGE switch for an exact meter
Crystal Detector HP-423A
reading (e.g., .5 on the DB meter scale). Record the
meter reading.
Adapter UG-201)IA/U
(6) Disconnect the hybrid attenuator under test
Adapter UG-60()/U
and connect the variable attenuator, as shown by broken
lines, figure 6-4.
Adapters CP7/CPS (2)
(7) Adjust the variable attenuator ATTENUATOR
Fixed Attenuator AT1/AT2 (2)
DB control for the same SWR indicator meter reading
recorded in step b(5). The ATTENUATOR DB control of
50-ohm Terminations (2), Microlab/FXR
the variable attenuator must indicate 0 +1.0, -0.0dB.
TA-6MN
(8) Correct the hybrid attenuator calibration tag
Cables W14/W15 (2)
marking, if incorrect.
Cable A1W3
(9) Disconnect the variable attenuator and
reconnect the hybrid attenuator, as shown by solid lines,
b. Procedure. Connect the equipment as shown in
solid lines (fig. 6-4), and proceed as follows:
(10) Record the readings on the meter of the
(1) On the signal generator, set the
standing wave ratio indicator for the hybrid attenuator
MEGACYCLES; dial to 1090 with the frequency control
ATTENUATOR control settings of 3.0, 6.0, 9.0, 12.0,
knob. Set the function switch to CW, and turn on the
15.0, 20.0, and 25.0.
signal generator. Allow a minimum of 20 minutes warm-
up period before proceeding.
(11) Disconnect the hybrid attenuator and
reconnect the variable attenuator, as shown by broken
(2) With the METER SCALE set to NORMAL, and
lines, figure 6-4.
INPUT SELECTOR set to XTA200KΩ, turn on the SWR
indicator and allow a minimum of 10 minutes warm-up
(12) Adjust the variable attenuator ATTENUATOR
period before proceeding.
DB control for the same SWR indicator meter readings
recorded in step (10).
Calibration of the hybrid
(3) Turn off the signal generator and zero set the
attenuator must be within the following limits:
OUTPUT VOLTS meter.
Hybrid attenuator settings
Variable attenuator settings
3.0
31.0dB
(4) Turn on the signal generator, and adjust the
6.0
61.0dB
OUTPUT LEVEL control knob for an OUTPUT VOLTS
9.0
91.0dB
meter indication at the SET LEVEL (+4 DBM) mark, with
the attenuator set to 0dB.
6-11
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