BC-348S BC-224L handbook.pdf

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1、ARMY AIR FORCES TECHNICAL ORDER NO. 08-10-166 INSTRUCTION BOOK FOR OPERATION AND MAINTENANCE OF RADIO RECEIVER BC-3484 RADIO RECEIVER BC-224-L RESTRICTED PUBLISHED BY AUTHORITY THE CHIEF SIGNAL OFFICER FOR AIRPLANE TYPE J d - t AAF Serial NO. Jz- 73 3r74/ I APRIL 2 1 , 1943 Digitally signed by Andy

2、(James A.) Moorer DN: CN = Andy (James A.) Moorer, O = Adobe Systems Incorporated, OU = Enterprise Services Reason: I am the author of this document Location: Panacea, Florida, USA Date: 2004.07.28 10:37:37 -0400 Output Connections . Bonding and Shielding. . Mounting of Radio Receiver . Safety Wire

3、. Ground - . - - - - - - - - - . - - - - - - - - - - - . . . b. Modulated Signal Reception . 5 c: C-W Reception . . 5 SECTION IV MAINTENANCE . . 7. ALIGNMENTOFI-FAMPLIFIER ;. . 6 . 8. TEST AND ADJUSTMI 6 . 9. CHECK AND ALIGN ME vr b- w vx.lLuxlvn. 6 10. ALIGNMENT OF R-F AMPLIFIER AND OSCILLATOR. . .

4、 7 SECTION V SUPPLEMENTARY DATA n h TABLE OF REPL Section I Pars. 1-2 Radio Receivers BC-3484 and BC-224-L have been converted from other production models (Radio Receivers BC-3484 and BC-224-C, respectively) by Belmont Radio Corporation, Chicago, Illinois. On equip- ments produced under this conver

5、sion, a name plate appears on the upper right of the panel of each of both types of receiver, identifying each equipment as Radio Receiver BC-348-S and Radio Receiver BC-224L, respectively, in addition to the name plate for the original receive-Radio Receivers BC-348-C and BC-224C -which appears on

6、the bottom right of the panel. Although this instruction book covers both Radio Receivers BC-348-S and BC-224-L, only the former will be referred to throughout the book for convenience in reference, as the two equipment5 are essentially iden- tical. See schematic diagrams, pages 19 and 21, for diffe

7、rences. Restricted - , - I - - - - - - - A - b . - - . fasten by means of the snapslides on the lower front corners of the c - - g. Safety 1 Pass sai slide assemblie twisted too tigh h. Grounc Connect the ground-binding post G by a short, direct, low-resistance lead to some grounded metal portion of

8、 the plane and solder at that point, if practicable. The lead should have enough slack to prevent vibration being transmitted to the receiver. Ilcar as pusslule ro me leau-ln insulaLor ana connect it from the insulator to the antenna binding post A ;h slack receiver. pacitor vitch in - - - . - -., Y

9、.Y U.-.V. Y.llY 2, and using the tuning control, tune in a signal at approxi- mately 3.5 mc to maximum signal strength. Reduce volume by means of the volume control knob until the signal is just audible. Adjust the ANTENNA ALIGN- MENT control to give maximum vohme. 1taUlU IGLGLVGL ub-ow-LI 13 a D G

10、I I - V I I L U UIUL, having its high-voltage Dower supply and all coil sets ubes, check them with the r tubes, well pushed down WIW ,I IfCY aGulrcw , CIL.CIYI ov,kets, are installed, that the tube shield is properly seated and that grid caps fit * tightly on the tubes. c. Check dial lights and fuse

11、s and see that they are properly and securely pl- d. Make sure that properly connected at and that the screws ho No other precautions ar e headset into m. . IuaLcu. the leads to the dynamotor are b. Using the TUNING knob and the dynamotor terminal strip the calibrated scale on the dial, tune Jding t

12、hem in place are tight. nal. NOTE: All tuning should be c e necessary. the volume control advanced only e -.TCITnm1,2 desired signal strength. In the ab: Section I1 Pars. 3-5 4. POWER CONNEL I IUI.Y Power to the radio receiver is controlled by the receiver AVC-OFF-MVC switch. The table below shows t

13、he power conneztions in conjunction with this m -: - - - . . : * - I - wrlerl w e lccclval uaa un completely installed, an operating test should be made as follows: a . Plug thl the TEL jack. Set the receiver switch,to MVC. lhe dynamotor should start and after the tubes have warmed up (aproximately

14、30 seconds), the volume control knob should be ad- vanced until a slight background noise is heard. Set the BAND SWITCH to the frequency band in which test signals are available. with reference to in the desired sig- lone on MVC with nough to give the jence of a signal, the setting of the volume con

15、trol can be judged by the loudness of the background noise. On MVC, with the volume control set at maximum, very strong carrier Radio Receiver BC-34.84 Pars. 7-9 SECTION IV MAINTENANCE 7. ALIGNMENT OF I-F AMPLIFIER The 4th i-f transformer (100) is slightly over- coupled with the resultant response p

16、eaks approxi- mately 5 kc each side of 915 kc. Connect the modu- lated test oscillator to the grid of Tube VT-93. Adjust primary and secondary tuning cores of the 4th i-f transformer so that even peaks are obtained at ap- proximately 920 kc and 910 kc with the slight dip between them at 915 kc. Visu

17、al adjustmmt may also be made with a cathode-ray oscilloscope. After ad- 8. TEST AND ADJUSTMENT OF CRYSTAL ) FILTER Connect a microammeter with a range of approx- imately 200 microamperes in series with the cathode return of the AVC volume control (59-B orange lead 1. Throw the CRYSTAL switch (105)

18、to the IN position and with an unmodulated 915 kc input from the test oscillator find the resonance peak of the crystal by slightly retuning the test oscillator until maximum deflection is indicated on the microammeter. The band width with an input voltage ratio of 10 X FIGURE 3-R.410 KECEIVER 1%-34

19、6-3, LOP VIEW OF LHASSIS justment of the 4th i-f transformer, couple the test is adjusted to approximately 2 kc by adjustment of oscillator to the grid of the converter Tube W-92 and the phasing trimmer (7). - adjust primary and secondary cores of the 3rd i-f (99), 9. CHECK AND ALIGNMENT OF C-W OSCI

20、L- 2nd i-f (97), crystal filter (96) and 1st i-f trans- LATOR former (95) to resonance. A 44NO-ohm output meter The c-w oscillator (98) is checked and adjusted by coupling the 915 kc i n u t (modulation off) to the is plugged into the phone jack (102) for observing. grid of the converter Tu Do not r

21、eadjust the 4th i-f transformer. C-w osc ON. With the none fre- ency and - - dign- those I. i 4-1 / Capacitor Alr trimmer 50 mmi max. Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Air tr

22、immer 50 rnmf max. Air trimmer 50 rnmf max. Air trimmer 25 rnmf max. Air trimmer 25 rnmf max. Air trimmer 25 rnmf max. Air trimmer 25 rnmf max. Air trimmer 25 rnmf max. Air trimmer 25 rnmf max. Air trimmer 25 rnmf max. Air trimmer 25 rnmf max. Air trimmer 25 rnmf max. Air trimmer 10 rnmf max. Air tr

23、immer 10 rnmf max. Mica 500 volts d-c .O1 mf * Mica 500 volts d-c .O1 mf * Mica 500 volts d-c .O1 mf * 10yo with leads 10% with leads 10% with lea& n t . trimmer R-F trimmer Det. trimmer R-F trimmer R-F trimmer Det. trimmer Det. trimmer Osc. trimmer Osc. trimmer Osc. trimmer Osc. trimmer Osc. trimme

24、r Crystal filter adjustment C-W osc. adjustment 1st R-F cathode by-pass 1st R-F screen by-pass 2nd R-F cathode by-pass I I with leads Function xondary tuning xondary tuning ransformer tuning primary tuning . secondary tuning econdary tuning rimary tuning rimary tuning tuning by-pass Inductance Induc

25、tance Inductance unction det. coupling det. coupling det. coupling det. coupling det. coupling det. coupling crystal coupling 1st I-F coupling 2nd I-F coupling te coupling 3rd I-F coupling 2nd det. coupling A 101-B 1 Choke 1 Audio freauency 1 Filter - Reference Vumber - - 116 117 121 - 251 252 253 2

26、54 255 256 301 302 2n2- A TABLE OF REPLACEABLE PARTS FOR RADIO RECEIVERS BG348-S AND BC-224L (Continued) Name Switch Switch Crystal assembly 1st I-F trans- former assembly 2nd I-F trans- former assembly 3rd I-F trans- former assembly 4th I-F trans- former assembly Crystal filter assembly C-W osc. as

27、sembly Choke Choke Pnnncitnr Description 6 position, 1 wafer 6 position, 1 wafer 915 kc crystal mounted in case Complete with shield can Complete with shield can Complete with shield can Complete with shield can Complete with shield can Complete with shield can R-F R-F P n n r 950 vnlt d-c 5 mf + 30

28、% Function Band switch, osc. unit Band switch, osc. unit I-F filter 1st det. to 1st I-F coupling 1st I-F to 2nd I-F coupling 2nd I-F to 3rd I-F coupling 3rd I-F to 2nd det. coupling I-F selectivity C-W re:eption Dynamotor filter Dynamotor filter nvnrrmntnr f%or L IAGRAM c- OFF-MVC + + OUF - - RELAY 1 4 V PUT 14V