Chapter 1. FUNCTIONING OF EQUIPMENT

TM 11-5820-549-50-1

CHAPTER 1

FUNCTIONING OF EQUIPMENT

changes, or additional publications pertaining to the

1-1. Scope

equipment.

a. This manual contains instructions for depot

maintenance of Receiving Set, Radio AN/ PRR-9(XE-9)

b. DA Pam 310-7. Refer to DA Pam 310-7 to

and depot overhaul standards. No direct support (DS)

determine whether these are modification work orders

or general support (GS) maintenance is authorized for

(MWO'S) pertaining to the equipment.

this equipment. The instructions include functioning of

the equipment, troubleshooting, repair, alinement, and

1-3. Reporting of Equipment Manual Improvements

testing. The manual also lists tools, materials, and test

equipment necessary to accomplish the maintenance.

The

reporting

errors,

omissions,

and

recommendations for improving this publication by the

b. Operation and organizational maintenance for

individual user is encouraged. Reports should be

the AN/PRR-9(XE-9) are covered in TM 11-5820-549-

submitted on DA Form 2028 (Recommended Changes

12-1.

to DA Publications) and forward direct to Commanding

General, U.S. Army Electronics Command, ATTN:

1-2. Indexes of Equipment Publications

AMSEL-ME-NMPAD, Fort Monmouth, NJ 07703.

a. DA Pam 310-4. Refer to the latest issue of DA

Pam 310-4 to determine whether there are new editions,

Section II. FUNCTIONING OF RECEIVING SET, RADIO AN/PRR-9(XE-9)

includes circuitry which, with associated external

NOTE

discrete components, performs the function of rf

Reference designations in this

amplifier, first mixer and local oscillator. Z2, the i.f.

section are abbreviated.

See

integrated circuit module, with associated external

schematic diagram, fig. 4-10, for

components, performs the functions of 10.7 MHz i.f.

complete reference designations.

amplifier, second mixer, second oscillator, and 455 kHz,

i.f. amplifier. The detector integrated circuit module Z5,

1-4. Block diagram, AN/PRR-9(XE-9) (fig. 1-1)

with other associated components, provides the limiter,

squelch and audio amplifier functions. Z3 contains

Receiving Set, Radio AN/PRR-9(XE-9) is capable of

diodes, resistors and capacitors of the discriminator

receiving a voice-modulated or tone-modulated

circuitry. Z4 contains the 150 Hz notch filter portion of

frequency-modulated (fm) signal within the frequency

the squelch circuit. For signals or functions of the

range of 47 to 57 megahertz (MHz). The specific

integrated circuit connection points, refer to the following

frequency of operation is crystal-controlled, and a

descriptions and the summary in paragraph 1-16.

change in the frequency is accomplished by changing

b. A signal received in the antenna of the receiver

the internal oscillator crystal. The set has the capability

is increased in amplitude by radio frequency (rf)

of either un-squelched or 150 Hz tone squelch

amplifier. The amplifier signal is applied to the first

operation. The signal path is shown in the block

mixer where it is mixed with the output of the local

diagram (fig. 1-1) and is discussed in a. through f.

oscillator, which is crystal-controlled. The first oscillator

below. For complete circuit details, refer to the overall

frequency is 10.7 MHz below the frequency of the

schematic diagram (fig. 4-10).

incoming signal, and as a result of mixing, a 10.7 MHz

intermediate frequency (i.f.) is developed.

a. The AN/PRR-9(XE-9) employs integrated

circuits and electronic component assemblies for many

of its functions. The rf integrated circuit module Z1

1-1