BC-191_BC-AA-191_serv_user_TM11-800_1942.pdf

RESTRICTED gI11-800 i!,hd l DSWAR DEPARTMENT, -. -,:. 118 !iCHNICAL MANUAL 194 .- RADIO TRANSMITTERS BC-l9l-A, o BC-l9l-B, BC-l9l-C, BC-191-D, BC-191-E, AND BC-AA-191 November 12. 1942 ,I y INIVl rOfCAI lNIA - U/13 , :;. r.II 11 800 RESTRICTED TtJt II. .eOO 19<I:l- TECHNICAL MANUAL) No. 11-800 W . THENT. WAIlmAfI,90telDber 12, 19f2. RADIO TRANSMITTERS BC-191-A, BC-191-B, BC-191-C, BC-191-D. BC-191-E, AND BC-AA-191 Caution: This equipment employs high voltages which are dan gero and may be fatal if contacted by operating or repair personnel. Never operate the ,transmitter with the shields removed and the high voltage cord inserted in the PL-li9 socket. Always momentarily short circuit every part to the chaSsis frame with lUI. insulated wire or screw driver - before working near it. Do this after all power BUppIy equip- ment has been turned oJ! or disconnected. The capacitors in this equip ment retain their electriCal charge for some time after the power source is removed and can ve . dangerous shock if this precaution is not observed. Never change fuses with the high voltage power supply connected. Make the necessary ground connections to power supply equipment and tranSmltter, following cording instructions on the chests issued with the radio set. Plraplpbl CHAPIZJt 1. GeneraL_ 1 CluPru 2. Radio transmitters BC-191-(). SEVIION I . General cll,aracteristics _ .:_ 2-10 II. Employment _ 11-2G Ill. Functioning of parts _ :. _ . _ U-28 IV. Servicing and repair _ _ 29-36 V. List of parts _ 37-39 CHA.; . 3. Radio transniitterBC-AA-191. SwnON 1.-General.characteristics _ r _ _ _ 40-60 II. EmploymenL _ lil-li7 Ill. Functioning. of pam _ GB-60 IV. Servicing and repair _ 61-63 V. List of. parts _ 64-66 Iaa_ INDU _ :. _ _ _ _ _ _ _ _ 133 M590261 1 Onq, ol, UNIVtl1im OfUUfORNlA TJ 11-800 1 SIGNAL CORPS CHAPTER 1 GENERAL Pa p.pb D11fereocel!l til modell_ _ _ _ _ 1 1. Differences in mode1s.-a. Radio transmitters BC-191-() and BC-AA-Ua with their associated equipment are designed for use as component parts of radio seta installed in aircraft, armored cars and other vehicles, 88 well as in portable ground stations. The basic circuit arrangements of the two types are similar. However, the older type BC-AA-191 requires the use of certain external equip- ment. In tlle BC-191-() transmitters the equivalent equipment is built into the transmitter case. In addition, the BC-191-(-) trans- mitters have greater frequency stability under varying temperatures and incorporate numerous circuit and mechanical refinements. h. In general, Ute various BC-191-() types are alike. The BC-191-A, the first type iSlUed, and the BO-I91- B, are alike except for improvements in the latter in the rotary antenna loading coil 1170 and. the switching relay 1165. The BO-I91-C, the third type issued, has a. toggle type OFF ON switch 1194 in place of the rotary type 1132 on the older sets. In addition, the A-C D-C and 12V. 14.2V. switches 1195 and 1190 respectively a.re of different design from the old switches 1136-1137 and 1139-1140 which they replace. A number of other minor changes distinguish the B0-191-:O from older models. The faces of the panel. meters are black with white lettering, while on the older models the faoes are white with black lettering. c. dio tr,nsmitter BO-191- D is like BO-191-C except for a redesigned filament resistor connection board and a redesigned antenna 16ading switch 1198 replacing switch 1171. These partS are interchangeable electrically and mechanically with those in the BC- 191-C. Radio transmitter BC-191- E includes the changes of the BC-191-D and in addition has a single unit filter capacitor block 1197a, 1197b, and 1197c, replacing three individual capacitors 1120, 1155, and 1163 in the older models. This part is interchangeable electrically, but not mechanically, with the three units it replaces. Fo. 8lmpUctt u<lio tro.,ittero 8C_191_A, flC-lOl_B, BC-lOI-C. BC_191_D .,4 BC-191_E will b6 rerred 10 a. BC-191_(O) 10 thll Ilaua! w re . u . ppll<able to all lueh _ . Th ( 0) Indlc.t . u lin t,paII. aldlo trl.mitte. BC-AA_IOIIs rJ . , . r.red to u BC-AA-UH . oNumbero . rn to puto I.,dlcated b, . me mbero III llIun,tlolIl . d <Ilspam. III this . .,Il the other is on the top panel at the right end. Cover the one which is not being used with the small shield M-191 which is fastened to the panel with the special screws provided. The physical location of the various components of each radio set will determine in which of the two positions the output terminal strip should be mounted. Cording diagrams on the radio set chests and in the pertinent Technical Manual contain this in- fonnation. g. The output terminal strip has a marking FRONT at one end. Be sure to install the strip with this marking toward the transmitter front for proper operation. Connect a heavy wire jumper between the binding post WAD A and WAD B, unless the antenna tuning unit BC-306-A is used. It. Sockets and jacks for making cording connections to power and control components are provided in duplicate, one set on the bottom (fig. 22), the other on the left side of the transmitter (fig 2). The physical location of components of a radio set determines which set 8 Onq, ol, UNIVtl1im Of UlJfORNlA I TM: 11-800 RADI O TRAN8M1TlERS Be-IIlI-(* ) AXO Be-AA- I II I 7-8 f sockets is used. Cover the unused sockets wilh the socket caps ,upplied with the transmitter. 8. Transmitter tuning units TU-3-A or -B, TU-5 to TU-IO-A or -B, TU-22-A or -B, and TU-26-B.- Thcse nine Y,eIJU 2._lIadlo tra n.nlur lIC- 191- 4 ) . It tra Mmlt cr .unlng unit p.o.rllllilyln.,rted howlnr one I ot OIO1 stages. The circuits of these units fUe shown in figUle 20, and theil function- ing is described in paragrnph 27. Each IHnillg unit hils the following 9 ( Or . fL, UNIVEIT,(Of CALIfORNIA TJ( 11-800 . u SIGNJ.L CORPS controls on its front panel: B M. O. TUNING; C P. A. TUNING; and ANT. COUPLING SWITCH D. Transmitter tuning units TU-a-A or -B, TU-6-A or - B, TU+A or -B, TU-22-A or - B, and TU-26-B also have a control marked BAND CHANGE SWITCH A. Concealed under the CALIBRATION CHART is a neutralizing capacitor adjustJ.llent control and lock. The CALIBRATION CHART may be removed for access to this control by unscrewing the four knurled thumbscrews at the corners of the chart. (See par. 3M.) 9. Vacuum tubes.- These transmitters use five vacuum tubes: 1 tube VT 4 C or VT-4-B as master oscillator (ro. 0.) 1 tube VT 4 C or VT-4-B as power amplifier (po a.) 2 tubes VT 4 Cor VT-4-B as modulators (mod.) 1 tube VT-2 :.8 H 0 0 , , , I 0 0 I I , lrllllsmitter to permit changing of tubes, removal of transmitter tUlling units, and adjustment of tuning controls. (4) TIle transmitter mounting FT- 151- A allows the equipment to float freely. For this reason the cording should not be filstelled down 12 UNIVElTY Of CAlifORNIA T_ 11 800. RADIO TRANSMITTERS BO-UII-() .urn BO-AA-Ul 11-12 closer than 18 inches from the transmitter. This will prevent vibra- tion from being transmitted to the unit through the fda. 12. Controla.-a. On trammitkr (fig. 4).-(1) Transmission is lccmnplished or controlled by-. (a) An antenna and a counterpoise connected to the ANT. binding post set TONE C. W. VOICE switch in the C. W. position; and set C. W. FIL. MOD. FIL. switch in the C. W. FIL. position. /. Set transmitter OFF ON switch in the ON position. This should afart the dynamotor. g. With a !Crew driver or short piece of wire W- l28 (or larger), make a connection between the utreme left stud on the C. W. FILA- MENT row and the stud on thaI4 VOLTS row directly under it. The master oscillator and power amplifier tube filaments (two of the vr 4 C tubes) should light and the FIL. VOLTAGE meter should give a reading. Progress to the right, stud by stud, until a connection between rows of studs is found that causes the FIL. VOLTAGE merer to read about 10.5 volts. -. TI.J9IS 11011111 5.-R.dlo tnlumltu. BC-JV1_(). Illamut .!.tor tontIOIl boan!. h. Set transmitter OFF ON switch in OFF position and connect one of the short links between the two studs just located, screwing it down securely. i. Set TONE C. W. VOICE at VOICE, and C. W. FIL. MOD. FIL. switch on MOD. FIL. position. 18 Onq, ol, UNIVtl1im OfUUfORNlA TK 11-800 RADIO TRANSMIlIJlRS BC-lIH-C) AND Bo-AA-lH 16 ;. Set OFF ON switch at ON. k. In a manner similar to that described in 9 above, begin at the ert.reme right end of the MOD. FILAMENT row and successively make connections to the stud directly beneath on the 14 VOLTS row Wltil a oonnection is found that will cause the FIL VOLTAGE meter to read shout 10.5 volts. 1. Set the OFF ON switch in the OFF position and connect a short link between the two studs. In. Set the C. W. FIT. MOD. Fn. switch on C. W. FIL. n. Set the OFF ON switch to the ON position. D. The continuous wave filament voltage will now be less than 10 volts. Using the method described in 9 above, but starting with the first stud to the right of the connection made in g, and moving to the right, dlltennine a stud on the COMPo row and one on the C. W. FILAMENT row directly below which will cause the FIL. VOLT A.GE meter to read ahout 10.5 volts. p. Set the OFF O:tf switch in the OFF position and connect a short link between the two studs, screwing it down securely, q. Shut off the vehicles engine, so that the battery is no longer on charge. r. Set the 12V. 14.2V. switch in the 12V. position, the TONE C. W. VOICE switch on C. W. and the C. W. FIL. MOD. FIL. switch on C. W. FIT. r. Plaoe the OFF ON switch in the ON position and allow the battery voltage to fall to a steady value on the FIL. VOLTAGE meter. It will be less than 10.5 volts. With a short. piece of wire, beginning at.the right endpf the C. W. FILAMENT row, successively connect between a stud on the C. W. FILAMENT row and the stud directly below it on the 12 VOLTS row, working to the left, stud by stud until a connection is found which gives a reading of about 10.5 fOlts on the FIL. VOLTAGE meter. t. Set OFF ON swit.,ch at OFF and connect a link between the two 8.uds, securing it with the screws . u. Set TONE C. W. VOICE switch on VOICE and C. W. FIL. MOD. FIL. switch on MOD. FIL. Place OFF ON switch at ON. e. Starting at the left end of the MOD. FILAMENT and 12 VOLTS rows, and using the method described in II above, successively move to the right until a connection is found that will cause a reading of ,bout 10.5 volts on the FIL. VOLTAGE meter. tI!. Place OFF ON switch at OFF. Connect the link remaining between the studs just located. z. Place 12V.14.2V. switch in 14.2V. position once more. y. Replace transmitter top and front cover of tube compartment. ,. . Or, ,I<. UNIVElII!TI Of AlIfORNIA TX 11-800 1- it does not disconnect the filament voltage.) . 11. Readjust the IDament voltage control on the rectifier unit 80 that a reading of approximately 10.5 volts appears on the FIL. VOLTAGE meter on the transmitter. i. Set TONE C. W. VOICE switch at C. W. All tube filaments should go out. j. Using a screw driver or a short piece of wire W- I28, make a con- nection between a stud at the left end of the C. W. F1I.A.MEJiT row and one directly below iton the 14 VOLTS row . k. Still maintaining this connection, take another short piece of wire, starting at the right end of the COMPo row, work to the lefi, stud by stud, successively connecting studs on the COMPo row and on t.he C. W. FILAMENT row directly beneath, until a cOMedion is found that gives a reading of about 10.6 volts on the transmitter FIL. VOLTAGE meter. l. If no connection will give this voltage reading, change the con_ nection between the studs made in operation j above, moving the con- nection to the next set of studs to the right . Onq, ol, UNIVtl1im Of UlJfORNlA TK 11-800 RADIO TRANSMlIIERS BC-191-() AND RC)-AA-191 18-17 m. Now repeat operation k above with the second piece of wire, until a reading of 10.5 volts is secured. If voltage is still low, repeat operation I above, moving the colneetion to the nert set of studs to the right and then repeating operation k above until the meter reads 10.1S VOLTS. When this adjustment is properly made, movement of t.he TONE C. W. VOICE switch through its three positions should cause practically no change in the reading of the FIL. VOLTAGE meter. flo. Tum off rectifier power rnpply equipment. o. Replace temporary wire connections between studs with the short links provided. p. Connect. a link between the two studs at the right end of the C. W. FILAMENT and 12 VOLTS rows. g. Replace top shield and tube compartment cover. This completes the adjustment. Minor voltage variations can now be adjusted for by use of the filament voltage control on the power supply equipment. If cording lengths are changed, or any major change made in the instaliation, repeat operations-(l to p above, if necessary. 17. Tuntng.-a. Preliminary oheck8.-(l) Make certain that aU power supply equipment is turned off. Check all cording to see that it follows the cording diagrams in the Technical Manual for the radio set. Set OFF ON switch at OFF. (2) Connect high voltage cord into sockets PW9 on the transmitter and power supply equipment. . (3) Connect antenna system to output tennino.l strip, following the diagrams in the radio set Technical Manual or the cording diagramS on the set chests. If transmission is to be made at frequencies of 800 kilocycles or lower, see 0(7) below and figure 9 for method of connect- ing antemia tuning unit BC-306-A. CGJltlon: When the p01JJer supply equipment ia darted or ftwned lUgh voUage ia p7elent in the trammitUr. BE OAREFULl (4) AdjuStment of the controls in the tube compartment can be made safely with high voltages connected, as there are no exposed high voltage elements, if all tubes are inserted in their sockets. Removal of the transmitter tuning unitirom the transmitter operates the safety interlock switch 1102 (fig. 4) which disconnects aU voltages from the transmitter. (6) The transmitter can be operated for continuous wave telegraph, tone or voice transmission. Adjrut tranlmitur initially for continu- (lUI tcaVe tra11l1niuion. Before the power is turned on, tune the transmitter appro:ZUnately asdescribed in (6) below. 28 , 0. ,. UNIVEI;fTi Of UlJfORNlA TH 11-800 17 SIG.!1AL CORPS (6) Insert transmitter tuning unit covering the frequency ronge in which transmission is t() be carried out and lock it in place with the snap slide catches. (