CHAPTER 4. DIRECT AND GENERAL SUPPORT MAINTENANCE

TM 11-5985-335-15

CHAPTER 4

DIRECT AND GENERAL SUPPORT MAINTENANCE

4-1.

Analysis of Operation

Signals from an associated transmitter are applied to the AS-1425/GRC feedhorn through a series of

waveguides. The mouth of the feedhorn is positioned so as to be at the focal center of the 4-1/2-foot parabolic reflector.

Polarization of the transmitted signal is determined prior to installation and is set by manual positioning of the feedhorn

mouth (para 2-6). The reflector radiates energy in a direction perpendicular to the plane of the parabolic reflector and

provides a gain of at least 33 db in the direction of radiation.

Signals received by the parabolic reflector are focused on the mouth of the feedhorn and applied to the

waveguide sections for conduction to an associated receiver. The angle of reception and gain is identical to that for

transmitting.

4-2.

General Maintenance Instructions

The preventive maintenance procedures performed at direct and general support categories of

maintenance are actions which have been designed to anticipate potential problem areas for the purpose of correcting a

possible trouble before it results in equipment outage. The action to be taken consists mainly of the-following:

(1)

Visual inspection of the equipment for the purpose of determining general condition, unusual noise, and

wear. Generally, the equipment will remain operational when these inspections are made.

(2)

Repair or replacement of parts that have a definite life expectancy.

The direct and general support maintenance procedures are not complete in themselves but supplement

the procedures performed at the organizational category of maintenance and include any additional techniques required

to perform maintenance on the AS-1425/GRC.

4-3.

Replacement of Components

The components of Antenna AS-1425/GRC can be readily identified upon visual inspection. Detailed parts removal

information is given in paragraphs 4-4 through 4-7.

4-4.

Removal and Replacement of Tilting Assemb ly

Removal.

(1)

Remove the tee bolt (fig. 2-4) securing the tilting assembly to the reflector.