BC-375E_serv_user_1942.pdf

GEI-16691 28,080 (5-42) PRELIMINARY INSTRUCTIONS FOR RADIO TRANSMITTER BC-375-E and Associated Equipment Manufactured by GENERAL ELECTRIC COMPANY U.S.A. Notice: This doc ent contains information affecting the national defense of the United States w t e meamng f the Espionage Act (U.S.C. 50:31, 32.) The transmissio f this revelation of its contents in any man- ner to any unaut rized person is prohibited. The information containe 1n marked RESTRICTED will not be communicated to the public or to the press, be communicated to any person known to be in the service of the United States an sons of un- doubted loyalty and discretion who are co-operating in governmental work. (AR-380-5). Published by Authority of The Chief Signal Officer Order No. 143-WFSCPD-42 . SAFETY TO HUMAN LIFE OPERATION OF THIS EQUIPMENT INVOLVES THE USE OF HIGH VOLTAGES WHICH ARE DANGER- OUS TO LIFE. OPERATING PERSONNEL MUST AT ALL TIMES OBSERVE ALL SAFETY REGULATIONS. DO NOT CHANGE TUBES OR MAKE ADJUSTMENTS INSIDE EQUIPMENT WITH HIGH VOLT AGE SUPPLY ON. DO NOT COMPLETE OR MAINTAIN ANY CON- , NECTION BETWEEN RADIO TRANSMITTER AND DYNAMOTOR UNIT UNLESS ALL SHIELDS ON THE RADIO TRANSMITTER ARE IN PLACE. KEEP AWAY FROM LIVE CIRCUITS 1. Under no circumstances should any person be per- mitted to operate the dynamotor unit with fuse box cover or end bells removed; or to replace fuses with power on; or to remove, place, or handle removed plugs with the dynamotor unit running. 2. Under no circumstances adjust circuits or service the equipment when the carrier is keyed off only. The radio transmitter uses a grid-bias keying circuit, which does not remove high voltage when the key is open. DO NOT OPERATE THE EQUIPMENT WITH SHIELDS REMOVED 11 8 TABLE OF CONTENTS SECTION I DESCRIPTION OF COMPLETE EQUIPMENT Par. 1. General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 1 2. 3. 4. 5. 6. 7. 8. 9. SECTION II INSTALLATION General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Radio Transmitter BC-375-E (Includes Mounting FT-151-A). . . . . . . . . . . . . . . . . . . . . . . . . . 1 Dynamotor Unit PE-73-C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Cords. . . . . . . . 2 Antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Antenna Tuning Unit BC-306-A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Reel RL-30-B and Connector Clamp MC-163 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Interconnection with the Radio Receiver in Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 SECTION III PREPARATION FOR USE 10/ General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 11. Radio Transmitter BC-375-E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 12. Operation at High Altitude. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 13. Dynamotor Unit PE-73-C. . . . . . . . . . . . 4 SECTION IV OPERATION 14. Radio Transmitter Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 15. Antenna Adjustments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 16. Dynamotor Unit PE-73-C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 17. Reel RL-30-B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 J 8. Operating Routine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 19. Summary Covering Normal Operation. . . . . . . . 9 SECTION V MAINTENANCE AND REPAIR 20. Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 21. Lubrication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 22. Service Notes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 iii LIST OF ILLUSTRATIONS Fig. 1. Radio Transmitter BC-375-E, Schematic Diagram Fig. 2. Radio Transmitter BC-375-E, Connection Diagram Fig. 3. Radio Transmitter BC-375-E, Dimensions and Weights Fig. 4. Transmitter Tuning Units, TU-5-B, TU-6-B, TU-7-B, TU-8-B, TU-9-B, TU-10-B, and TU-26-B; Schematic Diagrams Fig. 5. Transmitter Tuning Unit TU-5-B, Connection Diagram Fig. 6. Transmitter Tuning Unit TtJ-6-B, Connection Diagram Fig. 7. Transmitter Tuning Unit TU-7-B, Connection Diagram Fig. 8. Transmitter Tuning Unit TU-8-B, Connection Diagram Fig. 9. Transmitter Tuning Unit, TU-9-B, Connection Diagram Fig. 10. Transmitter Tuning Unit TU-10-B, Connection Diagram Fig. 11. Transmitter Tuning Unit TU-26-B, Connection Diagram Fig. 12. Case CS-48, Dimensions and Weight Fig. 13. Dynamotor Unit PE-73-C, Connection Diagram Fig. 14. Dynamotor Unit PE-73-C, Dimensions and Weights Fig. 15. Antenna Tuning Unit BC-306-A, Connection Diagram Fig. 16. Antenna Tuning Unit BC-306-A, Dimensions and Weights Fig. 17. Mounting FT-115-B, Dimensions and Weight I SECTION I DESCRIPTION OF COMPLETE EQUIPMENT 1. GENERAL Radio Transmitter BC-375-E with its associated equipment is designed for aircraft and for applica- tions requiring a medium power equipment with the characteristics of strength, light weight, flexibility and portability. The equipment is designed to provide communication by voice, tone, or continuous-wave telegraph over the frequency range of 150 to 12,500 kilocycles. However, only the frequencies covered by the transmitter tuning units listed in next column are available for use with this equipment. Suitable tuning equipment is provided in the radio transmitter to permit operation into a wide range of antennas over most of the frequency range. Antenna Tuning Unit BC-306-A may be used to extend the range of antenna tuning for frequencies between 150 and 800 kilocycles. 1. TU -5-B 1500-3000 kc 2. TU -6-B 3000-4500 kc 3. TU-7-B 4500-6200 kc 4. TU-8-B 6200-7700 kc 5. TU-9-B 7700-10,000 kc 6. TU-10-B 10,000-12,500 kc 7. TU-26-B 200-500 kc Dynamotor Unit PE-73-C furnishes the power required by the radio transmitter and operates from a 24/28 volt storage battery or other direct-current source used in aircraft. SECTION II INSTALLATION 2. GENERAL Radio Transmitter BC-375-E and associated equip- ment are part of aircraft radio sets. Installation con- ditions vary widely, and no detailed single set of installation instructions can be given in this book. However, separate instructions are furnished for each radio set and only such general instructions as can be followed in all installations are given in the following paragraphs. The requirements for shielding and bonding of cords in aircraft installations are very rigid, so that difficulties with extraneous pick-up from the radio receiver side tone and radio frequency from the power supply will be minimized. 3. RADIO TRANSMITTER BC-375-E (Includes Mounting FT -151-A) The radio transmitter outline dimensions and weights are shown in Fig. 3. The radio transmitter should be located in relation to its associated equipment so that dynamotor and antenna leads will be of minimum length. Two types of shock-absorber mountings are available for use with the radio transmitter: Mounting FT-151-A is a tray- type and is part of the Radio Transmitter BC-375-E. Mounting FT-115-B is a disposable-type. The tray- type mounting, to which the radio transmitter is attched by four snap-slide catches, is normally used. The disposal mounting is sometimes added near the top of the radio transmitter to prevent swaying. Mounting FT-115-B consists of a rubber button in a steel shell which may be attached to the top, bottom, or sides of the radio transmitter. Certain cover fastening screws of the radio transmitter have been placed so as to allow attachment of this mount- ing. 1 The radio transmitter should not be mounted closer than two inches from a wall, and in aircraft and vehicular installations it is desirable that Mounting FT-115-B be added at the top of the radio trans- mitter to prevent excessive swaying. The power cords should not be fastened nearer than 18 inches from the radio transmitter. This precaution prevents vibration from being transmitted to the unit through the cords. It is important that sufficient space be allowed in the front of the radio transmitter to facilitate replacement of tubes, removal of trans- mitter tuning units, and the making of tuning adjust- ments. After installation has been completed and tested, the snap-slide catches should be securely safety-wired at the places provided. 4. DYNAMOTOR UNIT PE-73-C The dynamotor unit should be mounted in an accessible position to allow access to the relay-fuse box, keeping in mind that the length of the leads from the battery to the dynamotor unit must be as short as practicable. This unit when operated in conjunction with Radio Transmitter BC-375-E draws from 20 to 30 amperes. No. 6 A WG or larger conductor should therefore be used for these leads in order to keep the voltage drop at a minimum. Mounting FT-107 should be securely attached so that the dynamotor unit cannot be torn loose by acceleration, vibration or shock. After the dynamotor unit is clamped securely to Mounting FT-107 by means of the four snap-slide catches, Plugs PL-59 and PL-61 of the applicable cords should be plugged in Sockets S0-39 and S0-41, respectively on the dynamotor unit. The primary leads from the battery should then be clamped securely to the proper binding posts on the dynamotor unit terminal board. 5. CORDS The cords to be used with the various radio sets are 1isted in the parts lists for same. Schematic diagram (Fig. 1) shows the necessary cording for the Radio Transmitter BC-375-E. Plug PL-64 and Socket S0-44 contain the necessary interconnections for the radio receiver and transmitter control. 6. ANTENNAS Because of the wide variety of antennas in the radio sets of which Radio Transmitter BC-375-E is a part, no specific details will be given for antenna installations. However, the following general pre- cautions should be observed: terminal A-TRANS on the antenna tuning unit to the antenna post on the radio transmitter; placing a jumper between LOADING TERMINALS A and B on the radio transmitter; and connecting the antenna to terminal B-ANT on the antenna tuning unit. This alternate connection should be used only if it is necessary to reduce the r-f voltages at the radio transmitter because of high altitude flashovers. The sensitivity of the radio receiver may be reduced slightly. The post marked GND on the antenna tuning unit should always be connected to the radio transmitter ground. 1. The antenna and ground leads should be made as short as possible, except where the length of lead-in is definitely determined by the placement of radio set and antenna. 2. Antenna leads should be insulated to withstand radio-frequency potentials as high as 5000 volts. 3. Antenna leads should be so placed that operat- ing personnel will not come in contact with them during normal operation of the equipment. Points accessible to personnel should be covered with Isolantite beads. 4. Ground connections should have as low resist- ance as possible. In aircraft installations the ground path should be well bonded. The GND post should always be connected to the ground system by a short lead, allowing, of course, for flexure due to vibration and shock. A link will be required between posts LOAD A and LOAD B when Antenna Tuning Unit BC-306-A is not used. 5. Antenna leads between the antenna and radio transmitter and between the radio transmitter and the radio receiver should be located as far as possible from any primary wiring of the airplane. This applies especially to the wiring to the dynamotor unit and is necessary in order to decrease the pick-up of electrical interference by the antenna circuit wiring. 7. ANTENNA TUNING UNIT BC-306-A This tuning unit is provided with Mounting FT-142. It should be mounted so that the tuning controls will be accessible during operation. It is desirable that the length of leads between the radio transmitter and the antenna tuning unit be kept to a minimum and that the leads be well insulated. Terminals A-TRANS and B-ANT on the antenna tuning unit are connected .to LOADING TER- MINALS A and B respectively on the radio trans- mitter when operation is with the low-frequency transmitter tuning unit (Transmitter Tuning Unit TU-26-B). However, at high altitudes (above 15,000 ft) and frequencies below approximately 400 kc, better operation may be obtained by connecting 8. REEL RL-30-B AND CONNECTOR CLAMP MC-163 The reel should be mounted in such a position that the crank is readily accessible and the counter is visible. In order to prevent excessive piling when the wire is being reeled in, the reel should be mounted at least six inches above the Eairlead and so placed that the point at which the antenna wire leaves the spool is in line with the axis of the fair lead; that is, for best operati011 there should be no bends in the antenna wire between the point where it leaves the reel and the far end of the fair lead. The four mounting bolts can be inserted in the reel base through the hole provided in the web of the spool. Unless the mount- ing screws themselves are grounded, a heavy ground- ing wire or strap could be clamped under the nut of one of the mounting screws for the purpose of thor- oughly grounding all metal parts of the reel. To fasten the antenna wire to the bottom of the spool channel it is fnst necessary to remove the spool cover by withdrawing it forward over the spool. This can best be clone by placing the fingers of both hands on opposite sides of the cover and pressing on the spool with the thumbs. The end of the wire