TM 55-4920-384-13&P
Section III. RADIO INTERFERENCE SUPPRESSION
4-3. Definition. The term "interference" as used
radio interference is generated anywhere a
herein applies to electrical disturbances in the
spark occurs or where a high-frequency cur-
radio frequency range which are generated by
rent is present. A spark is a small amount of
the test stand and which may interfere with
current jumping an air gap in response to the
the proper operation of radio receivers or other
force of a relatively high voltage. The gasoline
electronic equipment. The term "interference
engine ignition system is a common source.
suppression" as used herein applies to the
Magneto breaker points, relay contacts, and
methods used to eliminate or effectively re-
static changes collecting on the frame are
other common sources which in some way
stand.
must be suppressed.
4-4. Purpose of Interference Suppression. The
4-6. General Methods used to Attain Proper
tactical importance of effective interference
Suppression. Essentially, suppression is-at-
suppression cannot be stressed too greatly.
Since the electrical disturbance generated by
ground for the stray currents. The method
the test stand are composed partly of electrical
used to attain suppression include shielding
the ignition and high-frequency wires, ground-
be suppressed for two important reasons. First,
ing the frame with bonding straps if required.
they will interfere with the proper operation of
When a low or no charging rate is indicated,
the friendly radio set, and second, they will en-
inspect for loose connections, frayed or dam-
able the enemy to locate the equipment and its
aged wires, defective battery or ammeter. If
associated units.
none of these conditions exist, repair or replace
the alternator and/or regulator.
with a cloth dampened in an approved cleaning sol-
4-7. Engine Accessories. The engine acces-
vent and dry thoroughly. Clean corrosion from the
soriesconsist of the ignition magneto, elec-
electrical terminal of the starter.
(2) Inspect the terminal of the starter for cor-
integral regulator. For detailed maintenance
rosion and damaged threads.
(3) Remove the brush access cover and inspect
the starter internally for damage. Inspect the
a. Magneto. The magneto is a flange-mounted
brushes for oil soaked condition and excessive wear.
type, A permanent magnet, mounted on the rotor
If the brushes are less than half their original
shaft produces a high voltage current as its field
length replace the brushes. Refer a defective starter
passes through a fixed coil. The current produced is
to AVIM for overhaul.
fed to the spark plugs at the proper instant by a
distributor.
is a V-belt driven one wire system unit, with a built
b. Electrical Engine Starter. The electrical
in circuit regulator that can provide up to 40 amps
engine starter is a 24-volt, 4 brush, bendix drive
at 24 volts, for supplying current to the 24 volt test
type. The starter converts electrical energy from
stand battery.
the battery into mechanical power and transmits
this power to the engine flywheel for electrical
Cleaning, Inspection and Repair.
starting.
Cleaning and Inspection.
cloth dampened with an approved cleaning solvent
(1) Clean the external surfaces of the starter
