Manual Frequency Selection - TM-11-5820-222-350114

tacts 2 and 3 of S705C are closed by a cam,

B1201 through closed contacts 3

and 4 of relay K1202. The relay

and contacts 1 and 2 of S705C are opened.

also lifts the pawl from the detent

Thus, control of the frequency selector

wheel, which allows the tuning mo-

system is transferred from the CHAN SEL

tor to drive the l.0-mc automatic

selector switch on the front panel to the

CHANNEL selector switch, S1503, located

positioner through a slip clutch.

The l.0-mc seeking switch, S1203,

on Radio Set Control C-1439/U.

ganged to the 1.0-mc automatic po-

b. The ground circuit to channel selector

sitioner, rotates until the detent

automatic positioner relay K1204 is com-

reaches position 6. The ground cir-

pleted through contacts 6 and 8 of remote-

cuit to relay K1202 is then opened,

seeking switch S1206 and contacts 6 and 7

and the relay deenergizes and

of CHANNEL selector switch S1503 front.

drops the pawl into the detent wheel,

This causes tuning motor B1201 to drive

which prevents further rotation of

the preset channel memory drum and

the indicator, detent wheels, and

remote-seeking switch S1206 until there-

the l.0-mc seeking switch.

mote-seeking switch reaches the channel

(3) If the 1.0-mc seeking switch has

position selected by the CHANNEL switch

previously been set to a position

that opens the ground circuit to relay

lower than 6, it rotates counter-

K1204. Channel frequency selection is ac-

clockwise through positions 0 and

complished from the remote position in the

9 to reach position 6. At this in-

same manner as described for local chan-

stant, the detent on the rear wafer

nel selection (para 83).

of S1203 momentarily grounds the

10.0-mc automatic positioner re-

lay K1201 through switch contact

85. Manual Frequency Selection

B of S1203 rear. This allows time

(fig. 28)

for the 10.0-mc automatic posi-

When CHAN SEL switch S705 is turned

tioner to recycle to tune the uhf

to the MANUAL position, any one of the

tuning elements to the higher fre-

1,750 channel frequencies can be selected

quency setting:

by physically positioning the MANUAL

d. Operation of 0.1-MC Positions. The

FREQUENCY TENS, UNITS and TENTHS

right pin of the preset channel memory

controls S706, S707, and S708.

drum closes one of the 10 normally open

contacts of switch S1210D to control the

a. When S705 is turned to MANUAL, the

selection of the fourth digit of the preset

preset channel memory drum rotates to

channel frequency. Selection of this digit

position M. In this position, a nylon bar

is similar to the selection of the third

opens all contacts on switches S1210A

digit ( c above).

and S1210B (fig. 27). Switch contacts on

switches S1210C and S1210D are normally

Note. Once the preset chanel memory drum

open (fig. 27). Switch S705A is operated

reaches the selected channel and the +26.4 volts

is supplied to the 10.0-, the 1.0-, and the 0.1-mc

by a cam to connect TENS switch S706 to

automatic positioner relays K1201, K1202, and

10.0-mc seeking switch S1201 in place of

K1203, selection of the individual digits of the pre-

switches S1210A and S1210B. The wafers

set channel occurs simultaneously. Tuning motor

of the TENS, UNITS and TENTHS switches,

B1201 drives the automatic positioner systems

S706, S707 and S708, are grounded through

through slip clutches that permit the motor to run

switch contacts S705A-20, -21, -24, and

when any or all of the automatic positioners are at

-26.

rest.

Note. Figure 28 shows only the wiring required

84. Remote Channel Selection

to manually select frequencies of 220.0, 238.6,

(fig. 27)

320.0 and 338.6 mc. The controls and switches

are shown in the 220.0-mc position. For this ex-

a. When CHAN SEL selector switch S705

ample, assume that the MANUAL FREQUENCY

is on the REMOTE PRESET position, con-

controls are changed from 220.0 mc to 238.6 mc.