WARNING

TM 11-5820-921-40-2

NOTES

WARNING

This document contains the data necessary to facilitate maintenance and

Make sure the power is off before performing any cleaning inspection

servicing of Power Amplifier AM-6545/GRC-193, a component of Radio

or maintenance.

Set AN/GRC-193 and the vehicle mounted Radio Set AN/MRC-138.

Technical characteristics, assembly and component location and identifica-

tion and servicing diagrams including operational sequence, flow, test point

measurement data, and functional circuit blocks are contained herein.

WARNING

There are two alignment procedures applicable to Power Amplifier

Power amplifier tubes 1A14V1 and 1Al4V2 (Y-621B) contain BeO

(Beryllium Oxide Ceramics). The dust or fumes from BeO are highly

AM-6545/GRC-193 at this level of maintenance: The high voltage over-

toxic and breathing them can result in serious personal injury or

voltage threshold adjustment on DC control PWB assembly 1A2 and

death. Normal use of electron tubes containing BeO is safe. However,

never alter, disassemble, grind, lap, fire, chemically clean, or perform

the DC overvoltage adjustment on system control PWB assembly 1A3.

any other operation on any ceramic parts of the power tubes which

These alignment procedures are located on the figure associated with

could possibly generate dust of fumes.

the assembly upon which the procedure is performed.

Lubrication instructions applicable to the gear assemblies of tank circuit

module assembly 1A8 are in figure 2.

Only conventional tools and equipment are required to perform the alignment

procedures specified in note 2, above.

The parts location information given in this manual is essentially for the quick-

look ready use of maintenance personnel. The callouts and markings on these

Power Amplifier AM-6545/GRC-193 contains no fuse, but there are two

illustrations do not necessarily reflect the actual markings on the equipment.

circuit breakers for the +26.5 VDC. The 3 amp circuit breaker, shown on

The actual equipment markings may be harder to read due to manufac-

figure 5 and located on the front panel, is for the +26.5 VDC DIRECT to

turing processes such as soldering and coating.

Antenna Coupler CU-2064/GRC-193 and is labeled ANT CPLR CB. The 50

amp circuit breaker, shown on figure 5 and located on the front panel, is for

The test point values and conditions given on sheet 5 of figure 3 are those

the +26.5 VDC DIRECT to the Power Amplifier and is labeled PA CB.

encountered during Radio Sets AN/GRC-193 and AN/MRC-138 operation. If

equivalent power amplifier inputs are used, allowances must be made, as

The following warnings and cautions apply in the event circumstances warrant

necessary, for the indications observed.

them to protect personnel and the equipment:

WARNING

DANGER HIGH VOLTAGE

Dangerously high voltages (+1600 Vdc) are present on the plates of

power amplifier tubes 1A1V1 and 1A1V2 (Y-621B), tank circuit

module 1A8, plate assembly 1A9, and high voltage module 1Al3.

Do not touch any part of these components when the equipment

is energized.

iii