Power Amplifier Load and Tune Mechanism

TM 11-5820-509-35

NOTE

(b) Withdraw panel bushings (9) and

Carefully rotate the heatsink around

(28) from the front panel. Use care so that gaskets (10)

the axis of the power amplifier tube

and (29) and nylon sleeve bearings (69) and (95) are not

until its mounting holes match the

lost or damaged.

holes in the front panel of the

receiver-transmitter.

NOTE

Be sure that washers (67) and (100)

remain on the shafts of inductors

(3) Thread the plate cap and its lead through

(64) and (101) respectively.

the clearance hole in the heat sink and carefully attach it

to the plate electrode.

(7) Unsolder and tag the two insulated bus

(4) Position the overtemperature cutout on

wires that connect to lower front contact spring

the heat sink and carefully secure it in place with the two

assembly (74).

4-40 x 1/8 pan head screws.

(8) Carefully remove roller contacts (41),

(5) Orient the access hole cover and its

(56), (82), and (91) and their associated rods (42), (51),

gasket on the opening in the front panel of the RT-

(79), and (92) by removing 0-80 x 1/8 round head

671/PRC-47 and secure them in place with the four 8-32

screws (38), (44), (49), (57), (76), (85), (901 and (94)

x 1/2 flat head screws.

and their associated washers.

NOTE

(9) Remove E-ring (98) and spur gear (96)

This cover should be positioned so

from stub shaft (97).

that the attached chart can be easily

(10) Perform the procedures of paragraph 3-19

read.

a and carefully remove the front panel of the receiver-

transmitter so that sleeve bearings (35), (48), (69), and

(95) remain on their respective shafts.

(6) Replace the bottom cover on the power

amplifier compartment and secure it in place with the 4-

(11) If dial stop (14), support plate (12), lower

40 x 1/4 pan head screws.

front mounting block (73) or lower front contact spring

assembly (74) are defective, remove them as follows:

3-15. Power Amplifier Load and Tune Mechanism

(a) Remove lower front contact spring

(fig-3-89)

assembly (74) from lower front mounting block (73) by

CAUTION

removing 6-32 x 1/4 net head screws (77) and (78).

Disassemble

the

load-tune

(b) Remove the dial stop assembly and

mechanism only to the extent

lower front mounting block (73) from the panel of the

necessary to affect repairs.

Use

receiver-transmitter by removing 6-32 x 7/16 flat head

extreme care to avoid damage or

screw (13) and stud (18).

misalignment

roller

spring

assemblies 139), (45), (60), 174), (86),

NOTE

and 188).

If either dial stop (14) or support

plate (12) is defective, replace this

a. Disassembly Procedures.

assembly as a unit.

(1) Loosen and remove the 4-40 x 1/4 screws

(11 per cover) that secure the top and bottom covers to

(12) If upper front contact spring assembly (45)

the power amplifier compartment; remove both covers.

or upper front mounting block (46) is defective, proceed

(2) Remove E-ring (17) from its groove in the

as follows:

shaft of LOCK knob (15) and unscrew the knob from

(a) Remove the four 4-40 x 1/2 pan

stud (18). Open dial stop (14).

head screws that secure XMTR OUTPUT meter to the

(3) Loosen setscrews (2) and (20) and

front panel of the receiver-transmitter.

Carefully

remove POWER AMPLIFIER LOAD control knob (1)

withdraw the meter so that its gasket is not damaged.

and POWER AMPLIFIER TUNE control knob (21) from

Do not unsolder the meter leads.

their respective shafts.

(b) Remove 6-32 x 5/16 flat head

(4) Remove screws 14), (5), (23), and (24);

screws (31) and (32) that secure upper front mounting

then remove pointers (6) and (25). Withdraw primary

block (46) and upper front contact spring assembly (45)

scales (3) and (22) from collars (7) and (26).

to meter shield (33).

(5) Loosen and remove collars (7) and (26);

then remove secondary scales (8) and (27).

contact spring assembly (45) from upper front mounting

block (46) by removing 6-32 x 1/4 flat head screws (52)

(6) If panel bushings (9) and (28) are

and (53).

defective, remove them from the front panel of RT-

671/PRC-47 as follows:

(d) Remove meter shield (33) from the

(a) Loosen and remove hex nuts (68)

and (99).

3-104