TM-9-2350-273-BD
M48/M60 SERIES TANK, COMBAT FULL-TRACKED 105-MM GUN
TECHNICAL MANUAL; OPERATORS, ORGANIZATIONAL, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE; BATTLEFIELD DAMAGE ASSESSMENT AND REPAIR
TM-9-2350-273-BD - Page 191 of 288
TM 9-2350-276-BD
COMMUNICATIONS SYSTEM
Procedural Steps (Cont'd)
o. To calibrate the FREQUENCY DIAL, rotate the FREQUENCY TUNING KNOB
(27) while looking into the FREQUENCY DIAL VIEWING WINDOW (5) and select the
frequency listed below that is the closest to the desired operating frequency.
Band I:
22.050 MHZ 28.350 MHZ 34.650 MHZ
Band H:
36.225 MHZ 40.950 MHZ 42.525 MHZ 45.675 MHZ
48.825 MHZ
The frequencies are noted on the frequency dial with an extended graduation line
capped by an arrowhead.
P.
Set the MODE SELECTOR SWITCH (3) to the receive only (right) position.
q*
Depress and hold the TONE CALL BUTTON (25). A tone should be heard in
the earphones.
Rotate the FREQUENCY TUNING KNOB (27) until a zero beat is
obtained.
While rotating the FREQUENCY TUNING KNOB (27) the tone should be
heard to progress from a high pitch to a low pitch then to a high pitch again. The
proper setting of the FREQUENCY TUNING KNOB (27) is the point at which the tone is
at its lowest pitch or totally absent.
Note the relative positions of the index line and the frequency graduation line
through the FREQUENCY DIAL VIEWING WINDOW (5). If the index line is within 1/5
of a frequency graduation (5 KHZ), no adjustment of the index line is necessary.
Proceed after releasing the TONE CALL BUTTON (25). If the index line is not within
1/5 of a graduation (5 KHZ) the following adjustments must be made:
1. Release the TONE CALL BUTTON (25). Using a screwdriver, remove the
INDEX LINE ADJUSTMENT (4) plug.
NOTE
This adjustment is quite stiff. Care should be exercised to
not change the frequency setting while adjusting the index
line.
2.
Insert the screwdriver into the hole disclosed and contact the index line
adjustment. Rotate the adjustment right or left until the index line exactly corresponds
to the selected frequency graduation line.
3.
Replace the INDEX LINE ADJUSTMENT (4) plug.
4.
Check the setting by repeating steps (q) and (r). When no adjustment is
required, proceed to the next step.
s.
Return the MODE SELECTOR SWITCH (3) to the Simplex position (left).
11-36
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