Main Chassis and Front Panel Removal and Reassembly

TM 11-5820-509-35

resistor-switch subassembly in accordance with the

(6) Install and solder the receive antenna

details shown on the connection diagram (fig. 3-93).

lead (center of the shielded conductor) to the normally

closed contact (left side) of relay (17). Attach the short

(8) Attach the leads of OPR-TUNE switch

insulated bus wire between the ANTENNA connector

(44).

(bowl insulator) and the remaining contact of relay (17) if

(9) Insert the SMTR PWR switch (S103) into

it has been removed.

the relay bracket and connect the tagged wires.

(7) Reassemble the XMTR PWR switch

(10) Dress the cable harnesses neatly in

(S103) as follows:

grommets (26) and (42) and lace the harnesses, if

(a) Insert 4-40 x 2 1/4 round head

required.

screws (47) and (48) into detent (49); then install fiber

(11) Install the front panel of the receiver-

washers (53) and (55), and spacers (51) and (54) on

transmitter using the procedures detailed in paragraph

these screws.

3-19c.

(b) Install front switch wafer (56), fiber

washers (62) and (68), spacers (63) and (69), fiber

3-19. Main Chassis and Front Panel Removal and

washers (64) and (70) and then install rear switch wafer

Reassembly

(73).

(fig. 3-5, 3-87, 3-89 through 3-93)

flat washers (76) and (83), and hex nuts (77) and (84).

a. Disassembly

Procedures.

special

Tighten securely.

procedures are required to remove piece parts from the

(d) Insert potentiometer shaft (72) into

main chassis of the receiver-transmitter. The leads of

the shaft of detent (49).

each defective electrical component must first be

(e) Install hex nuts (78) and (85), and

unsoldered and tagged, and then the mounting hardware

flat washers (79) and (86) on the ends of screws (47)

removed. Remove the front panel and its associated

and (48); thread them onto these screws for a distance

parts from the main chassis using the following

of about 5/8-inch.

procedures.

(f) Insert potentiometer (90) into the

(1) Perform the procedures for removal of the

hole near the center of resistor-switch subassembly (87);

power amplifier load and tune mechanism detailed in

secure it in place with lock washer (81) and hex nut (80).

steps (1) through (9) of paragraph 315a.

Attach and solder the potentiometer leads.

(2) Loosen and remove the two circular

(g) Install resistor-switch subassembly

retaining nuts and hex nut that secure the AUDIO and

(87) on the ends of screws (47) and (48) until the slot in

POWER receptacles to the front panel.

the potentiometer rotor mates with the boss on the end

(3) On the front of the receiver-transmitter,

of the potentiometer shaft (72).

place the XMTR PWR switch to LO; the OPR-TUNE

switch to OPR; the CW-FSK/VOICE switch to VOICE;

NOTE

the POWER-LIGHTS switch to POWER OFF; and

Rotate the potentiometer shaft until

rotate the M ADJ control to it' clockwise stop.

the boss engages the slot in the

(4) Loosen the setscrews and remove the

rotor shaft of the potentiometer.

knobs from M ADJ, SMTR POOR, VOLUME and

POWER-LIGHTS controls.

(5) Loosen and remove the hex nuts (and

(h) Install flat washers (88) and (91)

boots) that secure the OPR-TUNE, BATTERY TEST,

and hex nuts (89) and (92) on the ends of screws (47)

and CW-FSK/VOICE switches to the front panel.

and (48).

(6) Unsolder and tag the wires attached to

NOTE

POWER 20A DC and POWER 5A AC fuses, the four

panel lamps, and SMTR OUTPUT meter.

Adjust hex nuts (78), (85), (89), and

(92)

until

resistor-switch

(7) Remove the four 8-32 x I/2 net head

subassembly 187) is perpendicular to

screws that secure the power amplifier tube access

the axis of the SMTR PWR switch,

cover to the front panel; carefully remove the cover and

its gasket.

and the rotor of potentiometer (90)

turns freely as shaft (72) is rotated.

(8) Remove the power amplifier tube using

the procedures detailed in paragraph 3-14a.

(9) Loosen the pan head screw and carefully

(i) Tighten the nuts against the

remove the bus wire and solder lug from the back of the

outboard surface of resistor-switch subassembly (87).

ANTENNA connector (bowl insulator).

(j) Connect

the

resistors

and

interconnecting leads between switch wafers and the

3-114