Figure 4-6. Equipment Receptacles, Removal and Installation

TM 10-3610-202-14 Section VII. RADIO INTERFERENCE SUPPRESSION 4-14. General Methods Used to Attain Proper Suppression. a. Essentially, suppression is attained by provide a low resistance path to ground for stray currents. The methods used include shielding the ignition and high- frequency wires, grounding the frame with bonding straps, and using capacitors and resistors. b. The term interference as used herein applies to electrical disturbances in the radio frequency range which are generated by the special warfare printing plant and which may interfere with the proper operation of radio receivers or other electronic equipment, or may enable the enemy to locate the equipment. c. The term interference suppression as used herein applies to the methods as used to eliminate or effectively reduce radio interference generated by the special warfare printing plant. d. The items of equipment which make up the editorial and photomechanical unit of the special warfare printing plant have been chosen to meet military requirements for radio interference suppression. All electric motors are either of the brushless type or, as in the Varityper composing machine, have built-in suppression features. The shelter construction is such that radio interference from the fluorescent lighting or other equipment is greatly reduced. 4-15. Interference Suppression Components. The equipment installed within the shelter system which could cause radio interference includes motors installed in the platemaker, composing machine, and air conditioner and the fluorescent lighting used for shelter and light table illumination. a. Motor Suppression. Motor suppression is achieved through the use of capacitors and appropriate shielding. Reference should be made to the applicable technical publication for the type and location of equipment radio suppression components. b. Fluorescent Lighting Suppression. Fluorescent lamps contain mercury vapor at low pressure. This vapor is ionized by a flow of electrons in the tube. The deionization that follows causes ultraviolet radiation which excites the internal phosphor coating causing it to radiate and give off light. The electron stream, or arc, in the tube is a source of radio interference. The interference may be radiated from the lamp or the power leads, or transmitted by conduction through a common power system. For systems that use starters, a capacitor may be placed across the starter terminals. Systems without starters usually have built-in capacitors mounted in the ballast, or current limiting device. It is impossible to suppress direct radiation from fluorescent lamps since shielding defeats the purpose for which the lamps are used. 4-16. Replacement of Suppression Components. Refer to the applicable technical publication for removal and installation of suppression components used in the platemaker, composing machine, air conditioning system and light table. 4-17. Testing of Radio Interference Suppression Components. Test capacitors for leaks and shorts on a capacitor tester; replace defective capacitors. If test equipment is not available and interference is indicated, isolate the cause of interference by the trial and error method of replacing each capacitor in turn until the cause is located and eliminated. Section VIII. MAINTENANCE OF CABINETS AND STORAGE COMPARTMENTS 4-18. File Cabinet Assembly. The file cabinet assembly is a ten-drawer unit installed at the left-hand shelter wall adjacent to the door. The upper drawers are provided with compartments for storage of smaller items. Label holders are attached to each to provide for content identi fication labels. An upper and lower locking clip permits insertion of a vertical locking bar to prevent movement of the drawer during shipment and storage (See fig. 4- 7.) The cabinet, which is of welded metal construction is used for storage of artist historic files and supplies. 4-23