TM 11-6625-524-14-2
output. There shall be no noticeable change in
(7) Connect the ME-30B/U from the center
ripple amplitude.
tap of the chopper driver coil (3G1) to the chassis.
( 1 1 ) Adjust CN-16B/U for a 126.5-volt
A reading of - 2.5-volt 20 percent should be
output. No noticeable change in ripple amplitude
indicated.
should occur.
(8) Allow UUT to operate for 24 hours and
recheck (5), (6), (7) above.
( 9 ) Connect the AN/USM-281 between
a. Test Equipment.
3A1TP1 and 3A1TP2 with vertical gain at 1
(1) Oscilloscope AN/URM-281.
millivolt/centimeter (rev/cm). Ripple shall be
(2) Oscillator AN/URM-127.
from 0.5 to 1 microvolt (rev) at 120 Hz.
(3) Voltmeter ME-30B/U.
(10) Adjust C N - 1 6 B / U f o r 1 0 3 . 5 v o l t
(4) Adapter, Millivac No. 900-2100.
(6) Set the LINE switch at ON.
b. Test Connections.
( 7 ) Connect the AN/USM-281 between
(1) Connect the AN/URM-127 to the di-
3A2TP8 and ground.
vider.
(8) Adjust t h e S E T R E F c o n t r o l f o r
(2) Connect the ME-30B/U to measure the
minimum n o i s e on the AN/USM-281. The
divider output voltage.
reading shall be approximately 30 mvPP.
(3) Connect the adapter to the output of the
(9) On the AN/URM-127, set the output for
divider.
1 volt. T h e AN/USM-281 shall read ap-
(4) Connect the UUT probe to the adapter.
proximately 300 mvPP and the waveshape shall
c. Procedure.
be sinusoidal.
(1) On the AN/URM-127, setthe output to 0
db on the 10 volt range at 60 Hz.
(2) With the UUT out of the case, use
a. Test Equipment.
aluminum shields on the bottom and left side to
(1) oscillator AN/URM-127.
shield the unit from stray signals. Connect the
(2) Voltmeter ME-30B/U.
shields to the unit chassis.
(3) Cable Assembly, RF CG-409H/U (4 FT)
(3) Connect the ME-30B/U at the junction
(2 each).
of 3A2R6 and C7 and ground. The reading on the
(4) BNC tee.
ME-30B/U shall he greater than 60 db.
b. Test Connections.
(4) Adjust the mechanical zero on the front
(1) Connect the 50-ohm termination to the rf
panel meter to SET REF.
probe and connect the probe to the UUT.
(5) Set the range selector switch at 0.001
(2) Connect one end of the CG-409H/U to
range.
the AN/URM-127 output.
