TM 11-6625-2575-14
Table 3-2. Connectors and Rear Panel Devices
Application
Designation
I
RF DETEC-
Input from device under test.
Application
Designation
TOR IN.
RF OUT ---------
Rf output available at this connector.
RF DETEC-
Output to VIDEO IN connector.
TOR OUT.
External level control signal input.
ALC --------
EXT
REAR PANEL DEVICES
MARKER.
VIDEO IN --
Input for detected rf output from device.
Application
Designation
Output to vertical channel of display.
SCOPE
F 1 - - - - - - - - - - Fuse receptacle.
VERT.
EXT DRIVE. Input for external sweep control signal.
Output to horizontal channel of display.
SCOPE
LINE -------- Power cord entrance to chassis.
HORIZ.
Section Il. OPERATION UNDER USUAL CONDITIONS
marker size control fully clockwise. Adjust the
3-3. Operator's Initial Adjustments
EXT MARKER SIZE control to produce the
maximum marker amplitude required.
a. Initial Control Adjustments. Determine the
b. Initial Adjustment of Associated Equip-
mode of operation pertinent to the test to be
ment. Make the necessary adjustments to asso-
accomplished, and set the controls of the AN/
ciated equipment.
USM-203A as follows:
c. Power Cord. Insert the power cord AN/
(1) BAND switch. Set this control to the
USM-203A into a receptacle supplying 115 volts,
LOW BAND (500 kHz to 300 MHz), or to the
60 Hz, single phase.
HIGH BAND (300 MHz to 1200 MHz), accord-
ing to the frequency range required.
3-4. Operating Procedures
dial to the frequency required.
USM-203A and associated equipment.
(3) SWEEP RATE. Determine the sweep
b. Check the initial adjustments of the AN/
rate best suited to display the results of the test.
USM-203A and any associated equipment.
(4) ALC control. Set the ALC control to
c. Apply power to associated equipment such
the internal monitor, unless it has been deter-
mined that an external level control is required.
power instrumentation.
d. Readjust the associated equipment to quies-
tenuation control to maximum (70 dB).
cent conditions (absence of inputs from the AN/
(6) MARKER switches. 1-MHz, 10-MHZ,
USM-203A).
and 50-MHz harmonic markers are provided. De-
e. Set the AN/USM-203A power switch to
termine the frequency marker interval (in MHz)
ON. The AN/USM-203A uses solid-state active
best suited to the range of sweep frequency to be
devices; the outputs develop immediately when
observed.
energized. Allow a warmup time of 20 minutes
(7) RF DETECTOR IN. Connect the de-
for the equipment to reach optimum stability.
vice under test to the detector input.
f. Upon applying power to the AN/USM-
(8) RF DETECTOR OUT. Connect the de-
203A, a signal will be delivered to the device
tector output to the VIDEO IN connector.
(9) VIDEO IN. Connect the RF DETEC-
mediately scan all associated equipment for evi-
TOR OUT connector to the VIDEO IN connector.
dence of out-of-limit operation which could re-
(10) FIXED MARKER SIZE. Set the fixed
marker size control to midrange.
g. Increase rf output of the AN/USM-203A
(11 ) MARKER SHAPER. Set the marker
play is presented on the external device.
shape control to midrange.
(12) EXT MARKER SIZE. If an external
h. Readjust associated equipment as necessary
marker generator is used, the input is connected
to adequately indicate or display the process un-
to the EXT MARKER connector. Set the fixed
der observation.