2-6.1. Erection Procedure of Antenna AS-1425/GRC with Kit, Antenna Extension MK-2228A/G (fig 2-9(a))
If the AS-1425/GRC antenna is to be raised to 100 ft, using Mast AB-621A/G with Extension Kit MK-2044/G, Antenna
Extension Kit MK-2228A/G must be used. Because only two out of three antennas and masts provided with the AN/TRC-
138 radio set are used at the same time, parts are to be utilized from the third unused mast and antenna. Needed are
three waveguides, CG-3307/GRC (15 ft, 0 in), and five waveguide clamps from the third unused AS-1425/GRC antenna
and four tensioners from the third unused AB-621A/G mast. The following lists the components needed to raise Antenna
AS-1425/GRC to 100 ft.
Elevation Control Rope
During installation of this equipment, conform to all safety requirements set forth in TB
SIG 291. Do not install antenna at a distance of less than twice the height of the mast
from power lines. Do not attempt antenna installation if the windspeed exceeds 25 miles
per hour (21.7 knots).
The AS-1425/GRC may be mounted on any adequate mast assembly by using a special mast adapter. (The mast must
be properly sited in accordance with para 2-3). Install each antenna by following the procedure outlined in a through I
Unload the wooden box and cartons containing Antenna AS-1425/GRC and Kit, Antenna Extension MK-2228A/G
near the mast. Also unload the three Waveguides CG-3307/GRC (15 ft, 0 in.)and five waveguide clamps from the
wooden box and cartons containing the third unused AS-1425/GRC antenna. Finally, remove four tensioners from the
guy assemblies of the third unused AB-621A/G mast.
b. Attach the antenna backmount to the antenna reflector with the pins provided in the reflector assembly as illustrated in
c. Using two people, lift the antenna reflector assembly and slide it onto the mast cap as shown in figure 2-4, and make
sure that the index marks on the two units match.