TM 11-5805-424-15/NAVELEX 0967-220-9010/TO 31W2-2G-41
CHAPTER 8
ADJUSTMENTS AND FINAL TESTING
8-1. General
(3) Operate the AC POWER switch to off and
then to ON.
a. All necessary adjustments for the MD674(P)/G
should be performed with the equipment in a normal
(4) If there is any delay in starting of the
operating environment.
However, the individual
oscillator, adjust inductor L1 and repeat the procedure in
adjustments may be made on a bench operated
(3) above until the oscillator produces an output with
equipment, and then, if necessary, touched-up after the
minimum delay after the AC POWER switch is operated
equipment is placed into operation. The necessary
from off to ON.
adjustments include the demodulator bias adjustment
(5) Connect the 140A oscilloscope between
and the transmit and receive alarm circuit adjustments,
pins 4 (signal) and 5 (ground) of PC 80034210, and
and order-wire circuit and oscillator adjustments.
repeat the procedures in (2), (3), and (4) above to adjust
b. The final testing procedures to check to see that
the space oscillator.
required equipment meets the minimum standards of
(6) After the adjustments are made as
new equipment are the same as described for general
described above, connect the 5233L electronic counter
support testing in chapter 7.
to pins 3 and 5 (mark oscillator) and then to pins 4 and 5
(space oscillator) and check to see that the output
8-2. Crystal Oscillator and Oven Assembly Module
frequencies are within 35 cps of the frequencies
indicated in the chart in c below.
(7) Replace oven cover.
a. General. To adjust the two oscillators in the
crystal oscillator and oven assembly, the cover of the
(8) Check oven temperature and adjust, if
assembly (fig. 2-6) must be removed to gain access to
required, in accordance with d below.
the variable inductors. Adjustment of the individual
crystal oscillator is performed by adjusting the inductor
c. Oscillator Frequency Chart.
until the oscillator starts. The output frequency is then
checked to see if it is within 35 cycles of the required
Mark oscillator
Space oscillator
frequency. The chart in c below lists the required mark
MX-73(*)/G
frequency (ke)
frequency (kc)
and space frequencies for each MX-73(*)/G.
MX-7372/G ----------
217.600
304.640
MX-7373/G ----------
261.120
435.200
CAUTION
MX-7374/G ----------
195.840
239.360
MX-7375/G ----------
174.080
348.160
MX-7376/G ----------
282.880
326.400
Bending of pin 3 can short out the
MX-7377/G ----------
152.320
195.840
oscillator signal, causing equipment
MX-7378/G ----------
184.960
206.720
MX-7379/G ----------
153.600
307.200
damage or incorrect reading. Ensure
MX-7380/G ----------
228.480
250.240
that this pin is not bent by connected
MX-7381/G ----------
239.360
282.880
test probes.
MX-7382/G ----------
272.000
293.760
MX-7383/G ----------
261.120
348.160
MX-7384/G ----------
157.760
168.640
MX-7385/G ----------
163.200
184.960
MX-7386/G ----------
179.520
190.400
(1) With the cover removed from the crystal
oscillator and oven assembly, connect the 140A
d. Oven Temperature Adjustment.
oscilloscope between pin 3 (signal) and pin 5 (ground) of
PC 80034210.
(1) Insert thermocouple probe of temperature
(2) Operate the AC POWER, switch to ON,
tester (Simpson Model 388-3L), NSN 6685-00-975-
and adjust inductor L1 (mark oscillator) until the
4544, into oven through screw hole in top cover.
oscillator starts (indicated by output waveform on the
140A oscilloscope).
Change 5
8-1
