SECTION VI. RADIO INTERFERENCE SUPPRESSION
GENERAL METHODS USED TO ATTAIN PROPER SUPPRESSION.
Essentially, suppression is attained by providing a low resistance path to ground for stray currents. The primary
methods used include: installation of capacitors on the combustion motor, and the incorporation of an interference
suppression filter in the filter and receptacle assembly (POWER RECEPTACLE). The secondary methods consist of
shielding on the ignition cable and the igniter.
PRIMARY INTERFERENCE SUPPRESSION COMPONENTS.
a. Two 0.47 microfarad, 10 ampere, 200 VDC capacitors (1, fig. 4-14) are installed in series in the combustion
motor. Their function is to suppress radio frequency (RF) interference generated by the arcing of the brushes at the motor
b. The filter and receptacle assembly (2) has an integral interference filter composed of resistors and capacitors.
The receptacle portion of this assembly is the POWER RECEPTACLE.
REPLACEMENT OF SUPPRESSION COMPONENTS.
This space heater contains dangerous voltages which can cause severe electrical
shock. Be sure to disconnect the power plug before repairing the heater.
a. Suppression capacitors are in the combustion motor assembly, and should be replaced only by direct support
b. To replace the filter and receptacle assembly, remove the side panel adjacent to the POWER RECEPTACLE.
Tag and unsolder the wires to the back of the filter, and remove the screws, nuts, and washers which secure the filter and
receptacle assembly to the heater case. This assembly is not repairable. Discard a defective receptacle and install a new
one in the reverse order of removal. Be sure to use rosin core electrical solder when soldering the wires to the back of the
SECONDARY SUPPRESSION COMPONENTS.
These are components which have radio interference suppression incidental or secondary to their primary function.
a. The ignition cable shielding acts as an interference suppressor. It is not repairable, and the entire ignition cable
must be replaced if the shielding is damaged.
b. The igniter has some shielding characteristics. It is not repairable. If it becomes a source of radio interference,