Matching Unit-Base MX-9146/GRC Removal and Replacement

TM 11-5985-355-13

(7) Secure ring (SMI-B-889201).

(1) Connect the AN/URM-182 between the

(8) Replace the AS-2732/GRC (a(3) and (4)

AS-2731/GRC and the receiver-transmitter unit.

above).

Antenna must be mounted upright in an open area away

from buildings and trees which would offset forward and

4-8. Matching Unit-Base MX-9146/GRC Re-

reflected power indications of the AN/URM-182.

moval and Replacement

(2) If the control cable is not used, set

a. Removal.

frequency selector switch S1 to the position that includes

(1) Remove safety lock wire between the

the operating frequency of the rt unit.

AS-2732/GRC and cable mount assembly.

b. Minimum Performance Tests.

(2) Remove the AS-2732/GRC from cable

(1) Set rt unit to frequency setting of 31.5

mount assembly.

MHz (subband 1). The AS-2731/GRC selector switch

(3) Remove rf and control cables from J1

must correspond with applicable subband according to

and J2. Place dust caps over connectors.

the frequency setting of rt unit.

(4) Remove MX-9146/GRC from antenna

NOTE

mounting bracket, bonding jumper and applicable

If automatic tuning is not used, manually set the

mounting hardware.

frequency selector switch of MX-9146/GRC to applicable

b. Replacement..

subband.

(1) Replace IMX-9146/GRC and bonding

(2) Key the transmitter, note and record

jumper to mounting bracket with applicable mounting

forward and reflected power indications. The required

hardware. Torque the four mounting bolts not to exceed

minimum forward power shall not be less than specified

100 inch-pounds (snug tight).

in the applicable rt unit manual, and reflected power shall

(2) Screw the AS-2732/GRC to cable mount

be less than 30 percent of forward power.

assembly.

(3) Repeat (1) and (2) above for the

(3) Install the safety lock wire (para 2-3f).

following frequency settings:

(4) Connect rf and control cables to MX-

(a) 35.0 MHz (subband 2).

9146/GRC J1 and J2 connectors respectively.

(b) 39.5 MHz (subband 3).

4-9. Using Test Set, RF Power AN/URM-182

with AS-2731/GRC

(d) 50.0 MHz (subband 5).

The AN/URM-182 (TM 11-6625-2718-14&P) is a

(e) 54.5 MHz (subband 6).

through-line directional wattmeter that measures rf

(f) 58.0 MHz (subband 7).

forward and reflected power in 50-ohm coaxial systems.

(g) 62.5 MHz (subband 8).

By observing forward and reflected power indications of

(h) 67.5 MHz (subband 9).

a transmitter, it can be deter mined whether or not

(i) 73.5 MHz (subband 10).

Antenna System AS-2731/GRC or the receiver-

The antenna may be painted using lusterless Forest

transmitter is defective.

Green paint (Item 5, appx E).

4-10. Painting

a. Test Setup (fig. 4-1).

Change 4-4