TM 9-4935-294-15/2
(f) Install gear (16) on the shaft of variable resistor
(6) Unsolder and remove the blue harness lead
(18). Do not tighten setscrew.
from terminal 2 on the dispersion PC board assembly
(g) Check counter setting and position of variable
(refer to 1, fig. 4-12).
resistor (18). Both settings must be as specified in (c)
(7) Remove clamp (10, fig. 4-14) then free and
and (d) above.
disconnect adapter (20).
(h) Secure gears to respective shafts with
(8) Remove four nuts (15), four washers (5) and
setscrews.
four screws (16) from tube brackets (17).
(9) Slide BWO tube (14) from rf head chassis
(41).
4-18. Disassembly and Assembly of L-Band
(10) Remove male connector contacts 7, 16, 19
Rf Head
and 23 (refer to 13, fig. 4-12) from connector (10, fig. 4-
To disassemble the L-band rf head, refer to exploded
12).
Follow applicable procedures as outlined in
view, figure 4-14, and wiring diagram, figure 4--15, and
paragraph 4--17 e (1).
follow procedures a through d below.
(11) Remove two tube brackets (17, fig. 4-14)
a.
Removal of BWO Tube 7923107.
Before
from BWO tube (14) by removing fourscrews (18) and
removing BWO tube, read and observe all instructions
four washers (5).
appearing on the tube and rf head case. Since BWO
b. Replacement of BWO Tube 7923107.
tube emanates strong magnetic fields, all work must be
(1) Obtain a replacement BWO tube; unpack
performed in a location free from possible magnetic
and inspect for possible shipping and/or handling
fields. Work surfaces and tools must be non-magnetic.
damage. If BWO tube is in satisfactory condition,
Refer to exploded view, figure 4-14, and wiring diagram,
proceed with the installation.
Perform installation
procedures in a location free from possible magnetic
Caution. Exercise extreme care when removing
fields. Work surfaces and tools must be non-magnetic
BWO tube to avoid damage to adjacent and related
.
electronic, electrical and mechanical components
Caution. The balun and N connector are integral
and assemblies.
parts of BWO tube and should not be disassembled.
(1) Remove left side cover (1, fig. 4-14) by
removing 10 screws (2) attaching it to rf head chassis
(2) Remove protective cover from the output
(41).
connector.
(3) Obtain four replacement male connector
Caution. The soldering Iron used should be
contacts 7923076. Obtain installation and crimping tool
pencil type, 15 watts or less, connected through a
7919871.
thermostatically controlled stand. Apply soldering
Note. To install the male connector contacts, follow
iron so it touches solder point only.
the applicable procedures outlined in paragraph 4-17 e
(2) Unsolder and remove the yellow and green
(2) (a).
harness leads from connector bracket assembly (8)
(4) Install male connector contact 7 (refer to 13,
solder lug (refer to 17, fig. 4-12).
(3) Remove clamp (8, fig. 4-14) by removing hex
(5) Install male connector contact 16 on black
nut (4), lockwasher (5), flat washer (6) and screw (7).
harness (heater) lead.
(4) Free connector bracket assembly (8) by
(6) Install male connector contact 19 on red
removing attaching screws (9).
harness (helix) lead.
(5) Place connector bracket assembly (8) on the
(7) Install male connector contact 23 on orange
adjacent work surface so that back of connector and
harness (collector) lead.
back of dispersion PC board assembly (refer to 1, fig. 4-
(8) Install tube brackets (17, fig. 4-14) on BWO
12) are accessible and in a convenient position for
tube (14) and attach with screws (18) and washers (5).
further disassembly.
Change 1 4-22
