BC-779B_BC-794B_BC-1004C_RA-74C_RA-84B_RA-94A_serv_user_TM11-866_1943.pdf

《BC-779B_BC-794B_BC-1004C_RA-74C_RA-84B_RA-94A_serv_user_TM11-866_1943.pdf》由会员分享，可在线阅读，更多相关《BC-779B_BC-794B_BC-1004C_RA-74C_RA-84B_RA-94A_serv_user_TM11-866_1943.pdf（103页珍藏版）》请在收音机爱好者资料库上搜索。

1、TM 11-866 WAR DEPARTMENT TECHNICAL MANUAL RADIO RECEIVERS BC-779-B, BC-794-B, and BC-I004-C and POWER SUPPLY UNITS RA-74-C, RA-84-B, and RA-94-A June 4, 1943 WAR DEPARTMENT Washington, June 4, 1943 This Technical Manual, published by J(ammarlu?d Mfg. Co. on : . order , is furnished for the informati

2、on and guidance of all concerned. . / . ADDENDUM I TO , TECHNICAL MANUAL TM 11-866 , FOR f RADIO SET SCR244B LIST OF COMPONENTS Quantity Nomenclature Stock No. 1 Radio Receiver BCI004C 1 Power Supply Unit RA94.A 1 Headset HS30B 2B830B 1 Cord CD605 3EI605-6.5 2 Insulator IN 124 3G624 6 Insulator IN 1

3、25 3G625 150 ft. Wire W151 IB151 150 ft. Wire W152 IB152 150 ft. Rope RP3 6Z7925 if TM 11-866 TECHNICAL MANUAL NO. 11.866 WAR DEPARTMENT Washington, June 4, 1943 Radio Receivers BC-779-B, BC-794-B LIST OF ILLUSTRATIONS FIGURE Page 1 Radio Receiver BC779B and Power Supply Unit RA94.A . VI 2 Radio Rec

4、eiver BC779B in Cabinet CHI04A . . 2 3 Power Supply Unit RA94.A, Front View . . . 4 4 Radio Receiver BC 779B, Front View . . . 6 5 Cable Connections for ac Operation . . . . . . 8 6 Cable Connections for Battery Operation . . . . . 8 7 Power Supply Unit RA94.A, Bottom View . . . . 9 8 Radio Receiver

5、 BC779B, Inside View . . 10 9 Power Supply Unit RA94.A, Inside View . . . . . 12 10 Power Supply Unit RA.94.A, Rear View . . . . . . 16 11 Radio Receiver BC779B, Bottom View . . 17 12 Radio Receiver BC779B, Alignment Chart . . . . . . . 38 13 Radio Receiver BC 794.B, Alignment Chart . . . . 39 14 Ra

6、dio Receiver BCI004C, Alignment Chart . . . . 40 15 Radio Reiver BC 779B, Selectivity . . . . . . . . 41 16 Radio Receiver BC 779.B, Sensitivity . . . 42 17 Radio Rceiver BC 779B, Fidelity . . . . 42 18 Radio Receiver BC779B, Location of Parts . . . . 43 19 Radio Receiver BC794.B, Location of Parts

7、. . . 44 20 Radio Receiver BCI004.C, Location of Parts . . . . 45 21 Power Snpply Unit RA 74C, Circuit Diagram . . . . 86 22 Power Supply Unit RA.84B, Circuit Diagram . . . . 87 23 Power Supply Unit RA94A, Circuit Diagram . . . . . . 88 24 Radio Receiver BC 779B, Circuit Diagram . . 89 25 Radio Rece

8、iver BC 794.B, Circuit Diagram . . . 90 26 Radio Receiver BClOO4C, Circuit Diagram . . 91 III TM 11-866 DESTRUCTION OF ABANDONED MATERIAL IN THE COMBAT ZONE In case it should hecome necessary to prevent the capture of this equipment, and when ordered to do so, DESTROY IT SO THAT NO PART OF IT CAN BE

9、 SALVAGED, RECOGNIZED OR USED BY THE ENEMY. BURN ALL PAPERS AND BOOKS. MEANS:- 1. Explosives, when provided. 2. Hammers, axes, sledges, or whatever heavy ohjects are readily availahle. 3. Burning hy means of incendiaries such as gasoline, oil, paper or wood. 4. Grenades and shots from available arms

10、. PROCEDURE :- 1. Ohliterate an identifying marks. Destroy nameplates and circuit lahels. 2. Demolish all panels, castings, switch and instrument-hoards. 3. Destroy all controls, switches, relays, connecting means and meters. 4. Rip out all wiring in electrical equipment. Smash water cooling, gas, a

11、nd oil systems in gas-engine generators, etc. 5. Smash every electrical or mechanical part whether rotating, moving or fixed. 6. Break up all operating instruments such as keys, phones, microphones, etc. 7. Destroy all classes of carrying cases, straps, containers, etc. DISPOSAL:- IV 1. Where possih

12、le, and when time permits, hury all debris or dispose of it in streams or other hodies of water. TM 11-866 SAFETY NOTICE Audio frequency voltages up to 150 volts may be present at the 600 ohm (SPKR) terminals under certain conditions. Turn the AUDIO GAIN control to 0 before touching these terminals.

13、 Never remove the sheet metal covers from the connector cable terminal strips without first detaching the plug from the a-c power line (or disconnecting the batteries); turning the OFF -ON switch to OFF is not enough. With dust cover and bottom plate removed from the re ceiver great care must be exe

14、rcised, as 250 volts direct current are present at several points on top of the chassis, and d-c voltages up to 400 and a-c voltages up to 260 exist at several points underneath the chassis. STILL GREATER CARE MUST BE TAKEN WHEN WORK ING ON THE POWER SUPPLY UNIT WITH THE BOTTOM PLATE OFF. HERE ARE D

15、-C VOJ.,TAGES OF OVER 400, AND A-C POTENTIALS UP TO 900 VOLTS. There is no high-voltage d-c electrical shock hazard during normal operation of this equipment after it has been properly connected and installed. v VI .Figure 1. Radio Receiver BC-779-B and power Supply Unit RA-94-A TM 11-866 1-2 SECTIO

16、N I-DESCRIPTION 1. GENERAL.- a. Receivers.-The radio receivers covered by this manual are superheterodyne receivers for the reception of amplitude modu lated (AM) signals and intended for fixedsfation use. The three receivers are identical except that each covers, in five bands, a differ ent frequen

17、cy range. RECEIVER Radio Receiver BC.779B Radio Receiver BC 794B Radio Receiver BCI004C FREQUENCY RANGE 100400 KC, 2500.20,000 KC 1,250.40,000 KC 540.20,000 KC These receivers can receive voice and continuous wave (CW) signals with either the MANUAL or AVC (automatic volume) control. b. Mechanical.-

18、Receivers and power supply units are rack models having front panel notches to fit the standard relay racks, dust covers fastened by knurled thumb nuts to front panel and rear edge of chassis, and bottom plates for protection against dust and damage in general. For table use, Cabinet CHI04A is furni

19、shed for the receivers. The power supply units can be used either in racks or on tables. 2. POWER SOURCES.-The receivers may be used with either of three power supply units as follows: Power Supply Unit RA84.B, designed to operate from a 105.115125.volt, 50.60.cycle power source; Power Supply Unit R

20、A.74C, designed to operate from a 9S.130.volt, 190.260.volt, 25.60.cycle power source; or Power Supply Unit RA94.A, designed to operate from a 1I5or 230.volt, 5060 cycle power source. The average power consumed is 180 watts. In an emergency any one of the receivers can be operated from a 6volt stora

21、ge battery, five 45volt B batteries, and a 45volt C battery connected as shown in FIG. 6. a. Total heater current required is 6.25 amperes at 6 volts. b. Total plate voltage required is 225 volts applied in the folloing manner: 225 volts at .117 amperes 90 volts at .0045 amperes c. c bias voltage re

22、quired is 45 volts at .010 amperes. 1 TM 11-866 2 Figure 2. Radio Receiver llC779B in Cabinet CH-104-A 3. WEIGHTS AND DIMENSIONS.- TM 11-866 3-4 a. Radio Receivers BC-779-B, BC-794-B and BC-I004-C are each 10Y2 inches high, 19 inches wide, and 15% inches deep behind front panel. Each receiver weighs

23、 55 pounds. When mounted in Cabinet CH-I04-A, each receiver is 12U inches high, 23 inches wide, 16% inches deep, and weighs 73 pounds. b. Power Supply Units RA-74-C, RA-84-B and RA-94-A are each 10Y2 inches high, 19 inches wide, and 10 inches deep behind front panel. Power Supply Unit RA-74-C weighs

24、 61 pounds. Power Supply Units RA-84-B and RA-94-A weigh 57 pounds each. 4. FREQUENCY BANDS.-The five frequency bands are marked in aluminum on the band-switch dial (FIG. 4). A large number of earlier models of this receiver already in the field can be identified only by the different frequencies sh

25、own on this dial. You can get the frequency band you want by turning the knob right or left until the band is on top (just beneath the up-and-down line above the dial). a. Frequency Coverage.- (1) Radio Receiver BC-779-B.- 100-200 kilocycles 2.5-5.0 megacycles 200-400 kilocycles 5-10 megacycles 10-2

26、0 megacycles (2) Radio Receiver BC-794-B.- 1250-2500 kilocycles 5-10 megacycles 2.5-5.0 megacycles 10-20 megacycles 20-40 megacycles (3) Radio Receiver BC-lOO4-C.- 540-1160 kilocycles 2.5-5.0 megacycles 1160-2500 kilocycles 5-10 megacycles 10-20 megacycles b. Besides the markings on the band-switch

27、dial (FIG. 4), a mask with windows shows a calibrated scale on the MAIN TUN- 1NG dial (FIG. 4) to correspond with the band selected by the band switch. This operation is automatic-when you turn the band switch, the mask on the MAIN TUNING dial turns with it since they are geared together. 3 TM 11-86

28、6 4 Figure 3. Power Supply Unit RA-94-A Front View TM 11-866 4-5 c. Band Spread.-A separate BAND SPREAD control CEI3) gives you simplified tuning over a narrow range of frequency. The BAND SPREAD dial (FIG. 4) has a scale reading from 0 to 100 through ahout 170. If set at 100, the frequency covered

29、by moving the dial will extend from that shown by the setting of the MAIN TUNING dial to some lower frequency, depending on how far the BAND SPREAD dial is moved. The capacity of the band.spread capacitor (C2) increases as the scale approaches zero (0). (1) To cover a specific range with the BAND SP

30、READ dial, first set the MAIN TUNING dial at the high-frequency end of the band you want to spread. d. Dial Calibration.-The MAIN TUNING dial is cali brated in frequencies like this (these calibrations hold true only when the BAND SPREAD dial is set at 100): (1) Radio Receiver BC-779-B.- BANI) 10 mc

31、 -20 mc 5.0 mc -10 mc 100 kc -200 kc 200 kc -400 kc 2.5 mc -5.0 mc CALIBRATION 100 kc per division 100 kc per division 2 kc per division 5 kc per division 50 kc per division (2) Radio Receiver BC-794-B.- BANI) 10 mc -20 mc 5.0 mc -10 mc 20 mc -40 mc 1250 kc-25oo kc 2.5 me -5.0 mc CALIBRATION 100 kc

32、per division 100 kc per division 500 kc per division 20 kc per division 50 kc per division (3) Radio Receiver BC-lO04-C.- BANI) CALIBRATION 10 mc -20 me 5.0 mc -10 mc 540 kc -1l60 kc 1160 kc-2500 kc 2.5 me -5.0 mc 100 kc per division 100 kc per division 10 kc per division 20 kc per division 50 kc pe

33、r division 5. POWER OUTPUT.-The total power output is about 8 watts. Undistorted power output is in the neighborhood of 3 watts with distortion increasing as the power output is increased. The receivers each have two output impedances with marked terminals along the rear edge of the chassis. 5 QI E9

34、 (T2 a T3) MAIN TUNING DIAL (C1) E10 (SW5) SW4 E11 (C1) SW6 BAND SWITCH DIAL (SW1 ) M1 BAND SPREAD DIAL (C2) J1 E14 (SW3) . . TM 11-866 5-7 a. The 600-ohm output (marked SPKR) is for use where a good deal of power is needed, such as for loud-speaker, recorder, or for a 600 ohm audio transmission lin

35、e. All power output measure ments and all audio-frequency fidelity readings are to be taken at this terminal. b. The 8000-ohm output (marked PHONES) is for monitor ing only. Do not try to take power measurements at this terminal. SECTION II-INSTALLATION AND OPERATION 6. INITIAL PROCEDURE.-Unpack the

36、 equipment and check it to see that it has not been banged up during shipment. Choose an operating position which will have as even temperature and as little humidity as possible. Steer clear of things that will cause vibration, such as wobbly tables, etc. 7. INSTALLATION.- a. Connection to Power Su

37、pply Unit.-Connect receiver to power supply unit as follows: (1) Remove the sheet metal covers from terminal strip (E4) on the rear of the receiver and terminal strip (EI) on the power supply unit. See that all ten screws on each strip are unscrewed at least three turns. Then attach one end of the c

38、onnector cable to each terminal strip exactly as shown in FIG. 5 and tighten all the screws securely. Make certain that each slotted spade lug on the cable strips makes contact with its respective screw terminal only, since a lug jammed between two of the screws could cause plenty of trouble. Then r

39、eplace both metal covers immediately, and dont ever remove them while the power supply unit is connected to the a-c power line. (2) The spacing of the spade lugs on the cable terminal strips is exactly the same as the spacing of the screws in the terminal strips on the receiver and power unit. If th

40、e two dont go together easily, DO NOT USE FORCE. Instead of cussing around and tear ing things apart, sit back and take a nice calm look to see if youve been going at it the right way. Be sure all the screws are unscrewed far enough. If one of the spade lugs has been bent or pushed out of place by r

41、ough handling, straighten it up and try again. The spade lugs should slip under the screws from the top (FIG. 5). b. Connection for Battery Operation.-The cable used for battery connection is the one with only one terminal strip (W2). 7 TM 11-866 8 RADIO RECEIVER BC-779-B, BC-794-B or BC-1004-C POWE

42、R SUPPLY UNIT RA-74-C, RA-84-B or RA-94-A 600w ANTENNA TERMINALS t o A.C. OPERATION Figure 5. Cable Connections for a-c Operation RADIO RECEIVER BC-779-B, BC-794-B or BC-1004-C 600w ANTENNA TERMINALS o 45V. B BATTERIES BATTERY OPERATION o A BATTERY Figure 6. Cable Connections for Battery Operation J

43、 Il. - Q: Q: Il. . (.) Figure 7. Power Supply Unit RA-94-A Bottom View TM 11-866 0 a: 0_ 0 . W Z- :J 9 TM 11-866 i= It) 10 N If) In CD :; :; If) If) . . o ;! :; Figure 8. Radio Receiver BC 779-B Inside View .: t I co f N t ( U I I ; i a: . I. , en . N (,) 1 , f N : I , j , f 1 j , ) TM 11-866 7 The

44、other end of it is made up of nine loose wires. Connect this cable according to FIG. 6 (note the color code for the nine loose wires). Connect this battery cable to the receiver first and replace the terminal cover before connecting the cable to the batteries. When discontinuing battery operation, d

45、isconnect the loose ends of the cable from the batteries before detaching the cable from the receiver. All operations of the receiver are the same with either the power supply unit or the battery set-up. c. Antenna.-The antenna input can be coupled to a bal anced transmission line of about 115 ohms

46、impedance or to a single wire antenna and ground. There is an electrostatic screen between primary and secondary of each antenna input transformer. This screening, plus a two-wire balanced lead-in, cuts noise pick-up to the least possible. (I) Transmission Line Lead In.-Connect the feeders to the te

47、rminals marked A at the rear of the receiver. (2) Single Wire Antenna.-If this is used, connect its lead-in to one of the A terminals. Connect the other A terminal to a good ground. NOTE: Youll get unusually satisfying results when receiv ing over a narrow band of high frequencies if you connect a s

48、uitably designed doublet or similar tuned antenna to the receiver through a good lead-in cable. (3) Ground.-You dont have to ground the receiver chassis but you can do it by connecting a wire under one of the thumb screws that hold the dust cover to the rear of the chassis. d. Earphones.-Plug your Headset HS-30 into the PHONES jack (Jl, FIG. 4) in the lower