Power Amplifier (A8A4A1) XMTR PWR Switch

TM 11-5820-509-35

(9) Dress the two insulated bus wires and the

c. Reassembly Procedures. Reassembly of the

power amplifier tube plate lead away from the load and

power amplifier plate capacitor switch assembly is

tune inductors and from other metallic objects in the

detailed in two parts: the switch components and

power amplifier compartment.

associated parts; and the installation of the assembled

switch into its position in the power amplifier

(10) Insert sleeve bearing (6) into the shaft

compartment.

Depending on the amount of

hole from the rear of panel (4). Carefully install fiber

disassembly that was performed, and the component

switch shaft (2) through the panel and sleeve bearing

parts that were replaced, some steps of the following

(6); then assemble washer (7), spur gear (8), and shaft

procedure may be omitted.

collar (9) on this shaft before inserting it in the rotors of

switch wafers (19) and (26).

(1) Reassemble the front switch wafer-

capacitor plate as follows:

CAUTION

(a) Attach capacitors (78) through (84)

Rock the fiber shaft gently as it is

to plate (73) with screws (28), (30), (32), (34), (36), (38),

inserted into the switch wafers to

and (40) using washers (27), (29), (31), (33), (35), (37),

index the switch properly without

and (39). Solder capacitor pigtails to the appropriate

damage.

terminal of wafer (19).

(b) Tighten studs (13) and-(16) in

(11) The shorting contacts of the switch rotors

sleeve nuts (5) and (11).

are oriented as shown in figure 3-91 when the

KILOCYCLES indicator on the front of RT-671/PRC-47

plate (73), heat deflector (12), spacers (14) and (17),

Align these rotors properly before

fiber washers (15) and 118). switch wafer (19), fiber

tightening setscrews (9) in shaft collar (10).

washers (20) and (23), spacers (21) and (24), fiber

washers (22) and (25), switch wafer (26), and fiber

NOTE

washers (45) and (71) into sleeve nuts (46) and (72);

The front face of spur gear (8) must

tighten the sleeve nuts snugly before attaching bracket

be flush with the front face of the

(85). Secure the bracket in place with 6-32 x 3/8 pan

mating idler gear in the gear train

head screws (87) and (103) using washers (86) and

before the shaft collar is secured in

(102).

place.

(2) Solder the insulated bus wire that passes

through heat deflector (12) to solder lug (69).

(12) If no further effort is required in the power

(3) Carefully install the switch assembly

amplifier compartment, replace the top and bottom

through the top of the power amplifier compartment and

cover and secure them with the 4-40 screws.

secure it in place with two 6-32 x 1/2 flat head screws

(1) and (3).

3-18. Power Amplifier (A8A4A1) XMTR PWR Switch

(4) Connect the shielded wire to the junction

(fig. 3-92, 3-93)

of capacitors (76) and (77) on plate (73), then secure the

shield attached to soldering lug 29A under screw (30)

a. Disassembly Procedures.

Disassemble the

and washer (29) and tighten.

power amplifier XMTR PWR switch assembly only to the

(5) Install 4-40 x 5/16 flat head screws (104)

extent necessary to accomplish repair.

and (105) through the side of power amplifier

(1) Remove the front panel of the receiver-

compartment (111) and secure bracket (85) with hex

transmitter using the procedures detailed in paragraph 3

nuts (107) and (108) and lock washers (106) and (109)

19a.

(6) Solder the insulated bus wire attached to

(2) Loosen rubber grommets (26) and (42)

suppressor 1741 to the lower front contact spring

from relay bracket (24); unsolder and tag the leads

assembly (fig. 3-89, item 74).

attached to switch wafers (56) and (73), and to resistor-

switch subassembly (87): carefully withdraw the XMTR

NOTE

PWR switch.

Apply a liberal amount of epoxy

insulating cement to this solder joint

(3) Disassemble the XMTR PWR switch as

after it has cooled. This will lessen

follows:

corona effects.

(a) Loosen and remove hex nuts (89)

and (92), and net washers (88), and (91). Unsolder and

tag resistors (65) and (74) from resistor-switch

(7) Carefully attach the plate cap to the

subassembly 187) and carefully remove the

electrode of the power amplifier tube.

subassembly from screws (47) and (48).

(8) Solder the insulated bus wire connected

(b) Remove flat washers (79) and (86)

to the large transmitting capacitor (C122) on the rear

and

wall of the power amplifier compartment to the center

post of capacitor (82).

3-112