TM 11-6625-586-45
CHAPTER 1
FUNCTIONING
Section I. GENERAL
tions, changes, or additional publications pertaining
1-1. Scope
to this equipment.
a. This manual contains general support and depot
b. DA Pam 310-7. Refer to DA Pam 310-7 to deter-
maintenance instructions for Generator, Signal
mine whether there are modification work orders
AN/URM-103. It includes instructions appropriate to
(MWO'S) pertaining to the equipment.
general support and depot maintenance for troub-
NOTE
leshooting, testing, calibrating, and repair of the
For other applicable forms and records,
equipment. It also lists test equipment required for
refer to paragraph 1-3, TM 11-6625-586-12.
general support and depot maintenance. Functional
1-2.1. Reporting of Errors
analysis of the equipment is covered in this chapter.
The reporting of errors, omissions, and recommen-
b. The complete technical manual for this equip-
ment includes two other publications, TM 11-6625-
dations for improving this manual by the individual
user is encouraged. Reports should be submitted on
586-12 and TM 11-6625-586-25P.
DA Form 2028 (Recommended Changes to Publica-
1-2. Indexes of Publications.
tions and Blank Forms) and forwarded direct to
a. DA Pam 310-4. Refer to the latest issue of DA
Commander, US Army Electronics Command,
Pam 310-4 to determine whether there are new edi-
ATTN: AMSEL-MA-Q, Fort Monmouth, NJ 07703.
Section Il. BLOCK DIAGRAM FUNCTIONING
1-3. Block Diagram
RF power level outputs of 62,500; 125,000; 250,000;
The AN/URM-103 consists of Generator, Signal SG
and 500,000 microvolt are also provided. Fixed IF
297/U housed in Case, Signal Generator CY-4695/
power level outputs from 10 microvolt to 1.0 volts in
URM-103. Generator, Signal SG-297/U (signal
decade steps are provided. A power monitor bridge is
generator) consists of a panel-chassis assembly in an
used to calibrate the RF and IF power level outputs
aluminum dust cover. The front panel has two hand-
by setting a constant power reference level. A 1 MHz
les to facilitate movement of the equipment and to
crystal calibrator provides precise frequency calib-
protect the controls. All operating controls, power
ration of the RF signals at 1 MHz intervals through-
cable, and receptacles for interconnecting the signal
out the frequency range of 18 to 80 MHz. Signal
generator are front-panel mounted. The signal
paths are shown in the block diagram (fig. 6-7) and
generator is a portable, all-transistorized FM signal
are discussed in a through p below. For complete
generator which provides both modulated and un-
circuit details, refer to the over-all schematic diag-
modulated RF signals over the frequency range
ram (fig. 6-8).
from 18 to 80 MHz. It produces power level outputs
from 0.05 microvolt to 500,000 microvolt across the
Q14, and Q15, supplies the internal modulating fre-
quencies for the RF oscillator. The FUNCTION
provides a nominal 50-ohm output impedance. The
switch S1 selects the desired internal modulation
generator has provisions for internal or external
frequency, a frequency calibration function, no mod-
sine wave modulation. The deviation from the center
ulation or external modulation, or an IF function.
frequency produced by the modulating signal can be
The selected function determines the input to the
controlled and measured by the deviation metering
m o d u l a t i o n amplifler.
b. Modulation Amplifier. When internal or exter-
section. The generator also produces IF alignment
frequencies which are crystal controlled. The unit is
nal modulation is selected, the modulation amplifier
equipped with crystals for operation at 4.3, 5.60,
transistors Q3 and Q4, amplify the selected modula-
5.625, 5.65, 10.00, and 11.50 MHz. Two additional crys-
tion frequency. The external modulation frequency
tal positions are provided for other IF's. A direct-
is applied to the modulation amplifier. When the
reading RF' attenuator dial is provided for power
internal modulation is used, it is available at INT
level outputs from 0.05 to 10,000 microvolt. Fixed
MOD OUT jack J4, at a level set by DEVIATION
Change 1 1-1
