BC-1306_repair_instructions_TM11-4009_1945.pdf

. uEFERENC COPY 0 WAR . 0 EPA I R T MEN T TEe H N I CAL MAN U A L REfERENCE COPl RADIO RECEIVER AND TRANSMITTER BC-1306 RE.P AIR INSTR UCTIONS RICTED MATTER. ATION OF RET rode o.r po.sitio.n orS1RC1D. DISSEMIN b virtue o.f his 9 Such matter IL is entitled so.llV cossifled matter. o.fficiol duties : :dge o.r po.ss:; ndiVidolS :so. porogroph d nlV to. eSSlo.n. . is entruste 0. wledge o.r Po.ss March 1944.) require such kn 2 0. 3.b, AR 380-5, 15 . rVA R DE PA R T MEN T JJ1A Y 194 5 . If? A R , , DEPARTMENT TECHNICAL MANVAL- TM 11-4009 RADIO RECEIVER AND TRANSMITTER BC-1306 REPAIR INSTRUCTIONS DEPARTMENT MAY ,. t I, + .1, . ,( ;1 ) l , . U 1?I1If fp, f I u ./. 15. , .;l 6 SECOND I.F. (TOP ANO BOTTOM TUNING) 7 GRID OF JAN-IRS 9 8-I-r 5 INPUT GRID OF JAN- IRS 11 ( (2V _ * _ -l-=CONTROL GRID OF JAN-IL4 10 Figu?e 2:1_ Ali.gnmcnt 1 Joints fo? 1eceive? of Radio Receive? and Tnmsmittm BC-1S06. nection of the receiver in series with a 250 mmf dummy antenna capacitor. (10) Set the signal generator dial to 6.2 mc with 30 percent, 400 cycles modulation. Vary the setting of the signal generators dial slightly above and below this point until maximum in- dication of the receiver output meter is ob- tained. The signal generators frequency is now exactly 6.2 mc and its dial setting should not be changed throughout the remainder of the re- ceiver alignment. (11) If the signal is received at the correct receiver dial reading, the oscillator is properly aligned. If the receiver dial does not indicate exactly 6.2 me, the oscillator must be realigned. Set the receiver dial to exactly 6.2 mc and ad- just the oscillator trimmer (point 1, fig. 23) for maximum indication on the output meter. Note. Some receivers will give a response at two ad- justments of this trimmer. When adjusting an oscil- lator whose trimmer gives two responses, it is always wise to shift the signal generator frequency to the image frequency, to assure that the image frequency is above thc signal frequency. If the signal frequency is 6.2 mc, the image should be heard when the genera- tor is tuned to 6.2 mc 1Jlns twice the intennediate f1e- qttency (6,200 kc plus 912 kc equals 7.112 mc). The out- put of the signal generator usually must be increased considerably to hear the response at the image fre- quency. If no signal is heard at the place where the image signal is supposed to be received, tune the gen- erator to the low side of the signal frequency and search for a response at a frequency lower than the signal frequency by an amount equal to twice the intermedi- ate frequency. In this case, 6,200 kc 6.2 mc) -912 kc equals 5,288 kc or 5.288 me. If te Image .frequency is below the signal frequency the OSCIllator tn,mmer has been adjusted to the wrong rsponse, Te SImple rule for adjusting an oscilla,tor tnmmer whIch gIves ,two responses is to set the tnmmer to he respone obtamed with the lesser capacity in the tnmmer. ThIs puts the oscillator above the signal fleqency. The response at the higher capacity puts, th oclllator frequency below the signal frequency whICh IS mcorrect, (12) With the hot lead of the signal genera- tor still connected to the antenna input, adjust the remaining trimmers of the r-f and con- verter stages (points 2 and 3, fig. 23), for maxi- mum reading of the output meter, being carefu1 not to move the tuning control. 3900 KG 4320 K,G 4940 KC 5760 KG _ TL 70799 Figure 24. Dial settings fr receiver of Radio Receiver and Transmttter Be-1906, c. CALIBRATION. (1) Turn the P<HONE-CW- NET-CAL switch to CAL. Disconnect the sig- nal generator. Turn the receiver dial to the lowest frequency check point (3,800 kc), and adjust the receiver TUNING knob until zero beat is obtained on ,the strongest beat note in the vicinity of the crystal check point. Turn the SENSITIVITY switch to the lowest setting that will give satisfactory crystal check points. This avoids weak spurious signals that are not the correct calibration check points. The re- ceiver is out of calibration by the amount that the index line on the dial window fails to co- incide with the exact frequency, Note whether or not the deviation is less than plus or minus 30 kc. (2) Having checked the calibration at 3,800 kc, proceed similarly through the entire tuning range checking the calibration a, t 4,000 lec, 4,200 kc, 4,400 kc, etc., up to 6,400 kc. (3) If at any point on the dial the calibra- tion of the receiver is off by more than plus or minus 30 lec, adjust the oscillator trimmer 22 (point 1, fig. 23) a slight amount in the direc- tion which improves calibration and recheck the calibration as described in steps (1) and (2) above. Continue making slight adjustments of the oscillator trimmer and rechecking the dial calibration until the deviation at each point is less than plus or minus 30 kc of the exact frequency. (4) Turn the PHONE-CW-NET-CAL switch to PHONE. Reconnect the signal generator to the antenna input of the receiver. Set the sig- nal generator dial to exactly 6.2 mc and tune the receiver for maximum reading of the out- put meter. Adjust the trimmers of the r-f and converter stages (points 2 and 3, fig. 23), for maximum reading of the output meter, being careful not to move the TUNING control. (5) Turn SEND-STANDBY-OFF switch on the transmitter I to OFF. Disconnect Cord CD- 1119 and the circuit test cable. Turn off and disconnect the signal generator. 19 . Transmitter a. PREPARATION. (1) Warm up the Frequency Meter Set, SCR-211 or equivalent, and tune same to 6,300 kc. (2) Remove the transmitter from the case carefully so as not to damage the p-a Tube JAN-2E22 on the chassis, left side rear. (3) Set the panel controls as follows (fig. 25) : (a) MO-CRYSTAL switch 135 at MO. (b) CW - MCW -PHONE switch 136 at PHONE. (c) ANT. SELECTOR switch 139 at 1. (d) ANT. TUNING knob 131 at any posi- tion above 5. Loose coupling is desired, there- fore, do not use any position below 5 as im- proper alignment may result. (e) Set FREQ. CONTROL knob to 6,300 kc. (See fig. 26 for method of reading dial.) (4) The antenna circuit MUST be loaded, with a dummy load during this test (fig. 19), consisting of a 10.5-ohm, 20-watt carbon or noninductive resistor in series with a 110-mmf capacitor and a 0-2. r-f ammeter. (5) The Power Cable CD-1086 and Battery Cable CD-1119 should now be securely locked into power receptacle 144 and battery recep- tacle 145 respectively. ( 6 ) Turn power on. (7) Insert the KEY cord plug into jack 150. Close KEY circuit and listen in on headphones 137 136 138 144 139 145 ANt SELECTOR (2) :11= 2 F REQ. CONTROL DIAL CLAMPING RING SCREWS (4) :11= 3 PANEL GUARD MTG. SCREWS (4) :11= 4 DIAL WINDOW SCREWS (3) # 5 CAPACITOR MTG. SCREWS 23 159 l3f 158 149 135 151 77 :11:5 15 134 TL 70761 Figu?e 25. Component parts on f?ont panel of trans?titte? of Radio Receiver and Tmnsmitter BC-1806. of the frequency meter for a signal from the transmitter. b. PROCEDURE. (1) Oscilla.tor tuning. Capaci- tor 76-A is a trimmer across capacitor 75-A, the oscillator section of ganged tuning capacitor assembly. Using an insulated screw driver, carefully adjust this MO trimmer (item 1, fig. 7) to exact zero beat of 6,300 Icc. A beat note or signal will be heard before and after the zero beat, while rotating this trimmer capacitor. The spot of no signal or zero beat indicates the alignment of the oscillator tank circuit to the 6,300-kc frequency. Note. Frequency Meter Set SCR-211 will produce beat notes between harmonics of the transmitter and the frequency meter. Care in the selection of the propel beat note frequency should be observed in order that improper alignment of the transmitter may be avoided. (2) P-a Tuning. (a) Capacitor 81 is a trim- mer across capacitor 75-B, the p-a grid circuit section of ganged tuning capacitor assembly. .-_-,0 THIS DIAL READS 995. 95 24 TL 70773 Figure 2G. D1:al ?eading8 fO? 1fransmitte? of Rndio Receive? and T?Cms?1tittc? DC-J30G. Using the 75-volt doc (direct-current) range of voltmeter, insert !the negative lead to prong 5 and the positive lead to prong 7 .of metering socket 143. Reference should be made to table IV. Using an insulated screw driver, peak the doubler grid circuit by carefully adjusting this trimmer (item 2, fig. 7) for maximum voltage reading of the voltmeter. This negative grid bias voltage may vary from minus 47 to minus 68 volts depending upon operating conditions and vacuum-tube tolerances. (b) Capacitor 86 is a trimmer across capaci- tor 75-C, the p-a plate section .of ganged tuning capacitor assembly. Using the 3-volt doc scale of the voltmeter, connect the positive lead to prong 2 and the negative lead to prong 8 of metering socket 143. (See table IV.) Ca,ution: High voltage -exercise extreme care to avoid bodily contact to ground. Using an insulated screw driver, carefully ad- just this p-a trimmer (item 3, fig. 7) for mini- m1,/,m reading of the voltmeter. Normal voltage readings are 0,05 volt on PHONE a,ncl 0,14 volt CWo This completes the alignment of the power amplifier. The transmitter is now fully aligned at 6,300 kc. (3) Operationa.l test. When these adjust- ments have been made, tune ANT. TUNING knob 131 for maximum brilliance as shown .on indicator 159. Maximum light is visible when the two red spots on the barrel of the indicator cover are lined up. For minimum passage of light rotate the outer rim clocl<vvise so the red spots are widely separated. This maximum bril- liance should coincide with the maximum cur- rent reading on the thermocouple ammeter of the dummy load, r-f metering .circuit. (See fig. 19.) The final frequency check should be made on each end of the frequency band. Retune the FREQ. CONTROL knob for each end frequency test, rotating knob 131 for maximum brilliance on each of these frequencies. to make sure an- tenna resonance is secured at each end .of the band. After the set has been properly aligned, turn off all power and disconnect all power cables, SECTION VI DETAILED TROUBLE-SHOOTING PROCEDURES 20. General a. PURPOSE. The purpQse .of this sectiQn is toO prQvide a systematic prQcedure fQr lQcalizing trQuble toO a particular stage. When a faulty stage is fQund, see sectiQn VIII f.or the repair prQcedure. b. RECEIVER. Since trQuble .in !the first i-f am- plifier stage, the calibrating QscillatQr stage, and the bfQ stage is lQcalized in aligning, nQ additiQnal trQuble-shQQting prQcedure foOl these sectiQns is given. c. TRANSMITTER. Lack .of audiQ-frequency PQwer fQr mQdulating the transmitter may .oc- cur either in the mQdulatQr stage .or in the sup- pressor grid .of the p-a stage. MQdulatiQn faults are lQcalized by resistance and vQltage checks. (See sec. VIII.) PrQbing fQr r-f shQuld be car- ried .out in accQrdance with !the procedure .out- lined in paragraph 23. 21. Receiver Second I-F Amplifier and Audio Stages a. PREPARATION. (1) Use the hook-up and CDntrDl settings described in paragraph 18. (2) Set the signal generatDr to 456 kc with 30 percent, 400 cycles modulation and with maximum Qu!tput voltage. Connect the ground of the signal generator to the GND. post of the receiver. CQnnect a clip lead in series with a .01-mf capacitDr toO the r-f post .of the signal generator and clip it !toO terminal 6 of sQcket 61. (3) CQnnect the ground .of the a-c (alternat- ing-current) vacuum-tube vQltmeter to the GND. post .of the receiver and the high PQst to an insulated test prDd, in series with a .01-mf capacitQr. b. TEST AND INDICATION. If there is nQ indi- catiQn .on the .output meter when alignment .of the !third i-f transfQrmer is begun, apply the vacuum-tube vQltmeter prQd, successively, toO the test PQints listed in table III, until a test pDint 1S found at which the voltmeter does not read. Check the stage .or sectiQn in which faulty op- eratiQn is indicated against the data in sectiQn VIII. Table III. Receive? second i-f a1nplijie? and audio stages. Apply voltmeter test prod If voltmeter does not read, to-faulty operation is indi- cated for- Terminal 3 of coil assem-2d i-f amplifi.er stage. bly 43-3. Terminal 3 of socket 62. Transformer 43-3 or diode detector section of Tube JAN-1S5 stage. Terminal 6 of socket 62. Terminal 5 of socket 62. Terminal 3 of socket 63. Terminal 2 of socket 63. Grid coupling section of Tube JAN-1S5 stage. Plate section of Tube J AN- lS5 stage. Grid-coupling section of au- dio-output stage. Plate circuit of audio-out- put stage. Terminal 5 of transform-Transformer 46 or associ- Tip of phone jack. Sv:itch 49 or associated wir- er 46. ated wiring. mg. 22. Receiver Radio-frequency and Converter Stages 25 a. PRELIMINARY. If, in aligning the receiver, the .output meter dQes nQt read when the signal generatQr is applied toO the antenna input .of the receiver after the audiQ system has been checked, either the r-f amplifier stage .or the h-f QscillatQr PQrtiQn .of the cQnverter stage may be at fault. The fQllQwing prQcedure shQuld be used in lQcalizing trouble to the faulty stage. b. PREPARATION. (1) Use the hQDk-up and cQntrQl settings described in paragraph 18. (2) Set the receiver dial toO 6.2 mc. (3) Set the signal generatQr to 6.2 mc with 30 percent, 400 cycles mQdulatiQn. (4) CQnnect the high r-f PQst .of the signal generatQr to an insulated test prod in series with a 250-mmf capacitor. CQnnect the grQund PQst .of the signal generatQr toO the grQund PQst of the receiver. c. TEST AND INDICATION. (1) Apply the sig- nal generator output, with a voltage of 1,000 microvolts, to terminal 6 of socket 59. If the output meter does not read, the oscillator sec- tion of the converter stage is faulty. (2) If the output meter indicates when sig- nal is applied to the mixer tube, but does not when the signal generator output at a voltage of 50 pV (microvolts) is applied to antenna jack 52, the r-f amplifier stage is faulty. 23. Transmitter R-F Stages a. PRELIMINARY. During all testing, it is im- perative that the r-f output circuit be loaded. A dummy load r-f metering circuit (fig. 19) con- sisting of a 10.5-ohm, 20-watt carbon or non- inductive resistor in series with a nO-mmf ca- pacitor and a 0-2 r-f ammeter is connected across the r-f output in place of the usual an- tenna. Probing for r-f is done with the aid of a neon lamp to locate the last point of r-f volt- age. Probing should begin at the oscillator stage, continuing through the p-a stage, through the keying relay 156 and the antenna tuning network to the antenna post 158. b. PREPARATION. (1) Remove transmitter from the case. (2) Install the dummy load. (3) Connect Cable CD-1086 to power recep- tacle 144. (4) Set the panel controls as follows: (a) MO-CRYSTALS switch 135 at MO. (b) CW-MCW-PHONE switch 136 at CWo (c) HIGH-MED.-LOW POWER switch 137 at HIGH. (d) ANT. SELECTOR switch 139 at 1. (e) FREQ. CONTROL knob at 6,000 kc. (5) Insert KEY cable plug into jack 150. (6) Turn power ON and close key circuit. (