PREOPERATION AND PERFORMANCE CHECKS
Adherence to the procedures outlined in this section is necessary for efficient operation of the radar set AN/MPQ-4A. The
procedures should be performed in sequence when possible.
Before applying power to the radar set AN/MPQ-4A, perform the following preliminary adjustments:
a. Receiver-Transmitter Group. Set the AFC-MANUAL switch on the control-monitor panel to the AFC position.
Secure the control-monitor panel, the power supply drawer, and the transmitter door. Open the air intake and air exhaust
panels on the rear of the cabinet and the air exhaust panel on the left side. Remove the vent cap at the upper left rear of
b. Antenna Group. Open the vents on both ends of the scanner and under the pedestal. Place circuit breaker
switch to on (HD-264A/MPQ-4A), open the purge valve. Open the air intake/exhaust panel on the front of the dehydrator.
Be sure that the azimuth stowlock is disengaged and that the fenders are down. Place the azimuth handwheel in the
desired operating position (normally all the way out). Open the vent under the elevation dial indicator housing (AN/MFP-4A
c. Control-Indicator Group. Secure the control-power supply, indicator, and computer drawers. Open the air
intake and exhaust panels on the left and right sides of the cabinet. Remove the vent cap at the upper right rear of the
cabinet. Set the following switches in the position indicated:
MAIN POWER switch
TEST METER SELECTOR switch
Check and start the generator PU-304C as outlined in TM 5-6115-450-15, section IV.
b. Check the power unit output for proper voltage and frequency. When these requirements are met, turn the
power unit 400-hertz circuit breaker to ON. The POWER UNIT indicator lamp on the control-indicator group will light,
providing the output phases of the generator are connected in the proper sequence.
Turn the MAIN POWER switch to ON. The MAIN POWER ON & INTLK CLOSED indicator lamp will light, and
the test meter on the control-power supply will indicate 27 volts. If the meter does not indicate 27 volts + 3
volts, turn the MAIN POWER switch off at once and check power input voltages and connections. If the 27V
fuse blows, turn