Section V. RADIO INTERFERENCE SUPPRESSION
system is a common source. Magneto breaker points,
102. Definitions
a.
Interference. The term "interference" as
charges collecting on the frame are other common
used herein applies to electrical disturbances in the
causes which in some way must be suppressed.
radio frequency range which are generated by the
105.
General Methods Used to Attain Proper
lubricating unit, and which may interfere with the proper
Suppression
operation of radio receivers or other electronic
equipment.
Essentially, suppression is attained by providing a
low-resistance path to ground the stray current. The
b.
Interference Suppression.
The term
methods used to attain suppression include shielding the
"interference suppression" as used herein applies to the
ignition, and high frequency wires, grounding the frame
methods used to eliminate or effectively reduce radio
with bonding straps, and using capacitor, filter, and
interference generated by the lubricating unit.
resistance circuits where necessary.
The gasoline
103. Purpose of Interference Suppression
engine is equipped with special shielded and suppressed
spark plugs (1, fig. 17), and braided metal sheaths over
The tactical importance of effective interference
the ignition cables (3) to suppress radio interference.
suppression cannot be stressed too greatly. Since the
The magneto (4) is bonded with tooth-type lockwashers
electrical disturbances generated by the lubricator are
and a capacitor inside the magneto to suppress radio
composed partly of electrical waves in the radio
interference.
frequency wave, they must be suppressed for two
important reasons. First, they will interfere with the
106. Replacement of Suppression Components
operation of the friendly radio net, and second, they will
a.
When replacing suppression parts make
enable the enemy to locate the equipment and its
sure replacement parts are correct.
associated units.
b.
Replace spark plugs and ignition cables with
104. General Sources of Interference
exact duplicates of the originals,
Generally, radio interference is generated
c.
Replace a defective capacitor. Tighten-any
anywhere a spark occurs or where high frequency
loose electrical connections. See that all tooth, type
current is present. A spark is a small amount of current
lockwashers are property placed arid secured.
jumping an air gap in response to the force of a
relatively high voltage. The gasoline engine ignition
1
Spark plugs
5
Cylinder air shroud
2
Tooth-type lockwashers, 3/8 in. (4 rqr)
6
Cylinder head
3
Ignition cables
7
Tooth-type lockwasher, /2 in. (4 rqr)
4
Magneto
8
Nut, x 13 (4 rqr)
Figure 17. Radio interference suppression.
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