RCA BTA-250M Instructions Manual Download | Manualshive

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Summary of Contents for BTA-250M

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Page 2: ... L Printed in U S A BTA 250M BROADCAST TRANSMlTTiR INSTRUCTIONS Manufactured by RADIO CORPORATION OF AMERICA ENGINEERING PRODUCTS DEPARTMENT Camden New Jersey U S A 16 30220 l ...

Page 3: ...wer Lighting Circuit A 8842553 CoilTurnsvsFrequency LlO5 8881438 I Inductance of L106 Antenna Resistance Above 70 Ohms 8881438 2 Inductance of L106 Antenna Resistance Below 70 Ohms 8881438 3 Coil Turns vs Inductance L106 and L107 8881438 4 Capacity of Cl20 Cl21 Cl22 Combination 8881438 5 Transmitter Front View Door Open Transmitter Rear View Door Open Outline Transmitter B 453333 Connection Diagra...

Page 4: ...h dry insulating material BREAK THE CIRCUIT by opening the power switch or by pulling the victim free of the live conductor DON T TOUCH VICTIM WITH YOUR BARE HANDS UNTIL THE CIRCUIT IS BROKEN FIRST AID A w LAY PATIENT ON STOMACH one arm extended the 8 other arm bent at elbow Turn face outward resting on hand or forearm 9 REMOVE FALSE TEETH TOBACCO OR GUM from patient s mouth 10 KNEEL STRADDLING PA...

Page 5: ...Place Jersey City 2 New Jersey 589 E Illinois Street Chicago I 1 Illinois 420 S San Pedro Street Los Angeles 13 California If for any reason it is desired to return tubes please return them to the place of purchase If this is not convenient please notify your RCA serving warehouse so that Return Authoriza tion may be forwarded to you PLEASE DO NOT RETURN TUBES DIRECTLY TO RCA WITHOUT AUTHORIZATION...

Page 6: ...cycles single phase Permissible Combined Line Voltage and Regulation 1 5 Power Consumption Zero Modulation 1 000 watts approx Average Program Modulation 1 15 0 watts approx 100 Modulation 1 400 watts approx Crystal Heater Input Power 1 17 volts 50 60 cycles single phase Crystal Heater Power Consumption 30 watts Monitoring Outputs Frequency 10 volts RMS 75 ohms Modulation 10 volts RMS 75 ohms MECHA...

Page 7: ...e Accessories Antenna Tuner Type BPA I I A including MI 28027A Remote Pick Up Assembly and MI 7 174 Antenna Ammeter ES 28906 A Remote Metering Kit less meter MI 2802 7 A Spare Crystal Unit TMV 129B MI 7467 Kit of Tubes Spares MI 28049 Kit of F C C Spare Tubes MI 28084 Electrical Side Shields per side Two MI 30546 G28 One MI 30546 G2 1 Audio Rack Type BR 84D less front door and side panels MI 3095 ...

Page 8: ...Figure I BTA 250M Transmitter 8 ...

Page 9: ...on transformer T102 makes it possible to modulate the screen of the buffer driver Vi0 1 as well as the screens and plates of PA tubes VI02 and VlO3 Potentiometers R155 R 158 and R 159 provide means for maintaining the overall hum at minimum level D c supply for the transmitter is furnished by two rectifiers High voltage for the modulator plates and the PA screens and plates is supplied by two type...

Page 10: ...e antenna current meter read ings when the tower lights are operating Also in certain localities provisions must be made for pre venting lightning damage and dissipating static charges which may accumulate on the tower Pre cautions taken during installation will prevent these operating difficulties and resultant equipment dam age Antenna Current Readings Under certain circumstances when the tower ...

Page 11: ...ss the base insulators These arc gaps should be carefully ad justed during bad weather which could be either dusty or humid conditions Spacing of the arc gaps should be set so that flashover occurs just beyond the point of 100 sine wave modulation If the gaps are properly spaced the gaps at time of discharge present a low impedance path to ground and will carry directly to ground any cur rent caus...

Page 12: ...meter MI 04 should indicate the voltage applied to the primaries of the filament transformers T106 and T107 Therefore if the measured voltage is other than 120 volts open the FILAMENT breaker and reconnect the power leads on T 106 and T107 to the taps next lowest to the measured voltage Then using an external meter of known accuracy measure all filament voltages at the tube sockets Adjust the FILA...

Page 13: ...ximately 100 however readings from 80 o to 120 o are normal If th e b ff u er grid current is low or the crys tal is sluggish in starting shut off all power and read just the oscillator plate choke tap If the frequency monitor output jack JIOI is not loaded the buffer grid current may be excessive duced by adjustment of RI 12 Current may be re After th e oscillator and buffer stages are func tioni...

Page 14: ...nect a l OOO cycle audio signal of suitable level to terminals TBA 2 and TBA 3 At 100 per cent modulation meter Ml 04 should indicate approximately 100 per cent in positions 8 and 9 of S 105 To adjust for minimum hum open the PLATE switch Rotate RI 55 to the extreme counterclock wise position and set RI 58 and RI 59 at the center position i e the shaft screwdriver slot must be vertical Reapply pow...

Page 15: ...esistance is less than 70 ohms therefore the reactance of L107 is 30 35 65 ohms 2 The inductance of L 107 is 15 9x 159 65 L 8 3 microhenries f 1250 3 From Figure 6 26 turns must be shorted 4 From Figure 5 the inductance of LlO6 should be 3 8 microhenries 5 From Figure 6 3 1 turns must be shorted 6 From Figure 7 the required shunt capacitance is 6200 mmf Note that since the antenna resist ance 20 o...

Page 16: ...TABLE 5 CONNECTIONS CAPACITORS C120 C121 Cl22 8842552 CAPACITANCE MMF CONNECTIONS 2 650 P2 I c122 2 820 3 900 Cl21 I 8 200 Cl22 12 100 14 100 16 ...

Page 17: ...Cl20 C121 Cl22 CAPACITOR VALUE Cl20 2 000 mmf AT 300 KC 2 2 amps Cl21 Cl22 3 900 mmf 3 4 amps 4 5 amps 5 5 amps 8 200 mmf 4 5 amps 6 0 amps 6 0 amps FREQUENCY IN KILOCYCLES Figure 3 Coil Turns vs Frequency L 105 888 1438 1 17 ...

Page 18: ...Figure 4 Inductance of L106 Antenna Resistance Above 70 Ohms 8881438 2 18 ...

Page 19: ...560 700 900 1100 1300 1500 1700 FREQUENCY IN KILOCYCLES Figure S Inductance of L106 Antenna Resistance Below 70 Ohms 8881438 3 19 ...

Page 20: ...z ...

Page 21: ...500 700 900 1100 1300 1500 1700 FREQUENCY IN Kl LO CYCLES Figure 7 Capacity of C720 Cl21 Cl22 Combination 8881438 S 21 ...

Page 22: ...mitter be kept free from dust and exces sive moisture Special care should be observed in the case of all insulators to avoid high resistance leaks A small electric hand blower may be used advantageously to blow dust from inaccessible places ically for poor contacts and loosened connections As far as possible tube failures should be antici pated by keeping a log of tube life and replacing tubes bef...

Page 23: ...7102 Figure 8 Transmitter front View Door Open 23 ...

Page 24: ...Tl08 RIO7 116 101 01 IO9 IO7 IO6 LllO Figure 9 Transmitter Rear View Door Open 24 ...

Page 25: ... 120C volt by pass Capacitor fixed mica 47 mmfd 15 2500 volt output coupling Capacitor fixed mica 0 002 mfd eS 2500 volt filter Capacitor headed lead type 1 mmfd tlO 500 volt feedback Eat used Capacitor fixed mica 0 01 mfd 20 1200 volt Capacitor fixed mica 150 mmfd lo 2500 volt Not used Capacitor same as Cl01 Not used Capacitor fixed mica 3300 mmfd rt20 2500 volt PA filament Capacitor fixed mica 2...

Page 26: ...5 93638 95012 z Description Stock No R134 R135 R136 R137 R138 R139 Resistor fixed ww with mtg brkt 2500 ohms t5 10 watt Resistor fixed ww 58 ohms l 1 watt Resistor fixed ww 600 ohms aloh 1 watt Resistor fixed ww 26 5 ohms lo 1 watt Resistor fixed ww 68 93640 93641 93642 93643 R140 R141 ohms aloh 1 watt Resistor fixed ww 11 5 95024 R142 R143 R144 R145 R146 R147 RI48 R149 R150 R151 R152 R153 R154 R1...

Page 27: ...shoulder x l 16 H Insulator Square pillar type steatite 3 s O D x 0 500 H 6 32 tap both ends x S 32 D 95509 17268 51088 54687 Description Stock No Insulator Cylindrical pil lar type steatite ak O D x 0 500 H 6 32 tap both ends x S 32 D _ _ _ Insulator Lead in bush ing steatite lr 4 O D x 7 g H 3 4 O D shoulder x l 32 H Insulator Lead thru bushing steatite s s O D x 3 g H 23 64 O D shoulder x r 4 H...

Page 28: ... A h TERMINAL BOARD SECTION A A SLOT FOR EXTERNAL WlRl NG A I Figure IO Outline Transmitter B 453333 28 ...

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Page 31: ...hematic Diagram Figure 12 make the following changes Delete the connection between terminal 8 of T103 and the Ml01 side of L107 thenadraw a connection between terminal 8 of T103 and the junction of L106 and LlOi b Draw a capacitor between the junction of SR103 and SIX104 and ground Label this capacitor C153 1 0 mf c Change the symbol number R154 to R163 d Draw a resistor in series with the line ru...

Page 32: ...Capacitor fixed oil filled 10 0 mf 400 v _________ __________ 450184 4 57017 2148 paper 1500 v 990193 71 99538 2149 to Cl52 Capacitor fixed 1 0 mf 100 o __________________ Capacitor fixed 0 005 200 o _ ___________ _ _________ mica mf 36091 520 Cl53 805004 4 Capacitor fixed lo _ paper 1 0 mf 1500 v 990193 44 96779 FlOl F102 Fuse crystal heater 1 amp __ _ _ __ 850339 6 19335 1101 Light indicator cry...

Page 33: ... fixed wire wound 75 ohm 50 10 w _ __ _ __ Resistor fixed composition 18 000 ohm 556 2 w _________ ___ Resistor fixed composition 5 ohm 75 w ___________________ ___ Resistor fixed composition 1000 ohm lo 2 w ____ Resistor variable wire wound 5000 ohm i20 3 w Resistor fixed wire wound 2700 ohm k5 5 w Resistor fixed wire wound 1600 ohm 55 w ___ _____ ___ _ __ Resistor variable 8 ohm lo 4 w _______ _...

Page 34: ...7 8 O D x l 2 H Insulator cylindrical pillar type steatite 3 4 0 D x l 1 2 If No IO 32 tap both ends x 3 8 D __ ___ _ __________ Knob control round fluted fits l 4 shaft black ___ ___ CRYSTAL OSCILLATOR UNIT MI 19458 Capacitor air variable 5 3 20 mmf crystal tuning _ Capacitor fixed mica 0 01 mf loo 200 v bypass e w Capacitor fixed mica 41 mmf f5 2500 v output coupling Capacitor fixed mica 0 002 m...

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