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Page Title:
Operation of 1-Mc Automatic Positioner |
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|  responds to a 3. Switch S1202 ro-
control the selection of the first two digits
tates at one-half the speed of S1201
as follows:
because of a 2:1 gear reduction. At
(1) The 10.0-mc automatic positioner
the time that the rotor contact on
relay, K1201, is controlled by the
S1201 makes contact with un-
settings of switches S1210A and
grounded contact 27, the rotor con-
S1210B. These switch settings are,
tact of S1202 makes contact with
in turn, controlled by the pin set-
switch contact 2 which is returned
tings on the preset channel mem-
to ground through S1210A. This ac-
ory drum. In this case, channel 19
tion grounds terminal 2 of K1201,
is preset to 376.3 mc and the 10.0-
which keeps the relay energized,
mc seeking switch (fig. 27) is
and switch S1201 continues to be
shown at rest in the 370.0-mc po-
driven by B1201 until the rotor con-
sition. If this switch is in any other
tact of S1201 lines up with contact
position at the time channel 19 is
37, which is ungrounded. Similarly,
selected, the ground circuit to re-
if 270.0 mc was the selected fre-
lay K1201 is completed and relay
quency, switch S1202 rear would
K1201 energizes.
provide a ground return (through
(2) When relay K1201 energizes, con-
contacts 4 and 17) for K1201 when
tacts 3 and 4 close; this applies
switch S1201 made contact with
+26.4 volts to tuning motor B1201.
ungrounded contact 37.
Relay K1201 also lifts the pawl
(5) Switch S1202 front is a blanking
from the detent wheel, which al-
switch that grounds terminal 2 of
lows tuning motor B1201 to drive
of K1201 when the uhf tuning ele-
the 10.0-mc automatic positioner
through a slip-clutch arrangement.
ments are tuned below 225.0 mc.
The tuning motor B1201 continues
During the blanked alternation of
to drive the automatic positioner
the tuning cycle, the tuning ele-
until the rotor contact of S1201
ments are returned to the 399.9-
makes with ungrounded contact 37.
mc position.
Relay K1201 denergizes, releases
c. Operation of 1-Mc Automatic Posi-
the pawl which falls into a detent
tioner.
on the 10-mc wheel, and thus pre-
(1) The right center pin (third pin,
vents further rotation of the posi-
counting from the left; (TM 11-
tioning wheel.
5820-222-10) ) of the preset chan-
(3) Note that several switch positions
nel memory drum closes one of
of the 10-mc seeking switch S1201
the 10 normally open contacts of
are tied together; for example,
switch S1210C. The closed con-
switch contacts 22 and 32, 23 and
tact represents the third digit of
33, 24 and 34, etc. In the example
the preset channel frequency. In
the example shown in figure 27,
shown in figure 27, neither con-
tact 27 nor 37 is grounded through
the channel 19 preset frequency
is 376.3 and contact 6 of S1201C
switch S1210B. To prevent switch
is closed by the right center pin
S1201 from stopping at contact 27
when 37 is selected, phasing switch
of the preset channel memory
S1202 rear returns terminal 2 of
drum. If the 1.0-mc automatic po-
sitioner is not in the 6-mc position,
K1201 to ground when seeking
contact 6 of switch S1210C com-
switch S1201 arrives at contact 27.
(4) The action of phasing switch S1202
pletes the ground circuit to relay
K1202 through 1.0-mc seeking-
r e a r is controlled by switch
switch contacts S1203 and wiper
S1210A. When 370.0 mc is selected
contact A.
S1210 can select either a 2 or a
3 for the first digit. In this case, the
(2) When relay K1202 energizes, +26.4
left pin opens the switch that cor-
volts dc is supplied to tuning motor
55
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