aircraft mounting panel and disconnect the
cable from the rear of the radio set control.
(1) Align the four captive retaining
screws on the external blower with the mount-
ing holes on the receiver-transmitter.
(1) Connect the radio set control cable
to the rear of the radio set control.
Caution: Do not twist, turn, or force
(2) Insert the radio set control into the
the external blower plug into the receiver-
aircraft mounting panel and fasten the four
Dzus fasteners securely. (Fasten the eight
(2) Push the external blower straight
Dzus fasteners on the C-6287/ARC-51BX (fig.
forward to connect the external blower plug
with the jack on the receiver-transmitter.
( 3 ) Fasten the external blower to the
3-18. Presetting Channels
receiver-transmitter with the four captive re-
taining screws; tighten securely with the No.
Perform the procedures given below to preset
6 Allen wrench.
channels to desired frequency.
3-16. Removal and Replacement of
a. Loosen the two holddown screws (fig. 1-
2) in the memory drum access door and open
the door (fig. 2-2).
b. Turn the preset channel control to the
(1) Disconnect pendant cable connector
P1 from the receiver-transmitter jack (figs.
channel to be preset, as indicated on the right
side of the memory drum (fig. 22). Disregard
1-1 and 1-5).
the channel number shown in the preset chan-
(2) Disconnect antenna cable connector
nel indicator; this is not the channel being
J1 from the reflectometer antenna connector
(3) Loosen the three Phillips-head cap-
c. With the preset tool mounted in the mem-
tive retaining screws which fasten the reflecto-
ory drum access area, move the eight adjustable
meter to the receiver-transmitter dust cover.
pins according to designation and letter code
on the memory drum access door cover to pre-
set the channels to desired frequency. The three
(1) Align the three Phillips-head captive
center digits (252) are selected with two pins
retaining screws on the reflectometer with the
for each number according to the letter code
mounting holes on the receiver-transmitter
on the memory drum access door cover. The
dust cover; tighten the captive screws securely.
hundreds digit (2 or 3) and the hundredths
(2) Connect pendant cable connector P1
digit (0 to 5) are selected by a single pin for
to the receiver-transmitter jack (fig. l-l).
either digit, as designated on the control.
(3) Connect antenna cable connector J1
Note. Make sure that the adjustable pins are firmly
to the reflectometer antenna connector.
seated before rotating the memory drum to the next
3-17. Removal and Replacement of Radio
d. Record the channel frequencies on the
chart provided on the front of the memory
drum access door, in accordance with the chan-
(1) Loosen the four captive Dzus fasten-
nel indicated on the right side of the memory
ers which secure the radio set control to the
aircraft mounting panel (fig. 11). (Remove
e. Replace the preset tool in its holder.
the eight Dzus fasteners on the C-6287/ARC-
5IBX (fig. 1-2).)
f. Close the memory drum access door and
(2) Pull the radio set control out of the
tighten the two holddown screws.