FUNCTIONING OF EQUIPMENT
changes, or additional publications pertaining to the
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.
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
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
discrete components, performs the function of rf
Reference designations in this
amplifier, first mixer and local oscillator. Z2, the i.f.
section are abbreviated.
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,
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