Instruction manual

TM 11-6625-3017-14
5.4.3Power supply
Test equipment:- a, b, c and d
(1) Measure the output of the -18 V and -12 V
regulated supplies at the points illustrated in
Fig. 5-2..
Fig. 5-2. Regulated supply measuring paints
If the voltages are not within ±1% of nominal, adjust
RV1 for -18 V or RV2 for -12 V.
The location of these potentiometers is illustrated in Fig.
4.1.
(2) Connect the wave analyser to the -18 V line and
check that the 50 Hz, 120 Hz and i80 Hz ripple
components are each less than 100 µ-V. Check
that the same components on the -12 V line are
each less than 50 -µ V.
(3) Replace the wave analyser with the differential
voltmeter. Check that the -18 V line voltage does
not change by more than ±20 mV when the a. c.
supply is varied from 180 to 260 V, (or 90 to 130 V).
The change on the
-12 V line should be not more than +2 mV,
and preferably about +1 mV.
5.4.4 Local oscillator
Test equipment:- e, f, g' and h
(1) Connect the frequency meter and millivolt-meter via
a T-connector to the output plug of the oscillator,
PLB. Turn the LEVEL control fully clockwise.
(2) Switch to oscillator RANGE 1-2, tune through the
range and check that the dial calibration is within
±3% of the frequency meter reading and that the
level is between 0.5 V and 1 V. If the calibration
accuracy is outside limits, withdraw the local
oscillator unit and reset range trimmer L2 for
optimum accuracy at the low frequency end and/or
C1 at the high frequency end. Replace the local
oscillator unit and recheck the calibration.
(3) Switch to oscillator RANGE 3-4, tune through the
range and check that the dial calibration is within
+3% of the frequency meter reading and that the
level is between 0.6 V and 0.8 V. If the calibration
accuracy is outside limits withdraw the local
oscillator unit and reset range trimmer LA for
optimum accuracy at the low frequency end and/or
C14 at the high frequency end. Replace the local
oscillator unit and recheck the calibration.
(4) Switch to oscillator RANGE 3-4 and turn the
CRYSTAL switch to position 1. Insert a 22 MHz
crystal into socket 1 and check that the frequency
meter reads within 22 MHz
±
the crystal tolerance
after tuning the Local Oscillator to 22 MHz.
5.4.5 Harmonic generator
Test equipment:- i.
(1) Shunt the resistor in series with the I. F. OUT
socket by a 1 k2 resistor.
(2) Connect the I. F. OUT socket to the R. F. • Input of
the Polyskop and the R. F. IN socket to the R. F.
Output of the Polyskop.
(3) Set the Polyskop controls as follows:
5-5