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111 ... 1.. AN ART-13 100 WATT TRANSMITTER Designed to provide radio communication by voice, (MCW) or CW telegraphy. Class "B" audio modulator system capable of modulating the carrier at least 90 °.6 on voice or MCW. Incorporates automatic tuning mechanism which may be used to select any one of 11 frequencies, range 2000 KC to 18,100 KC. Frequencies 200 KC to 1500 KC range is provided by addition of oscillator 0 -16. ART -13A. Removed from aircraft $39.50 90 7 r 5 .7 Less Meters 29.50 0 -16 Low frequency oscillator coil for ART -13. Excellent 9.95 24 Volt dynamotor for ART -13 14.95 APN -4 Loran equipment with new receiver R9B with tubes and indicator !DOB-less tubes and crystal $29.95 Brand new, complete with 24 vnit inverter $89.50 07 .7 APN -9 Complete, like new, with 12 or 24 volt inverter $129.50 R 44 /ARR -5 -AM OR FM RECEIVER 27 to 143 MC Military Version of Hallicrafter S -27. Less Power Supply. EXC 559.50 Less Tuning Meter 44.50 HI -FI HEADSET. 600 OHM. NEW $7.95 HS -23 -2000 Ohm Headphones. NEW 4.95 CD- 307 -Extension Cord for above .97 LM- Frequency Meter Heterodyne, crystal calibrated. Modulated covering frequencies from 125 KC to 20,000 KC continuously. This equipment provides accuracies of .02 per cent in the 2000 to 20,000 KC band. With original crystal and calibration book. Shipping wt. 30 lbs. Brand new $59.50 Used. Excellent 39.50 TA -12 XMTR, 100 Watt. EXC $19.95 MP -28 MODULATOR and 28 V. DC Power Supply for above. EXC 14.95 Meter- 3 " -0 -5 Ma. 270° Indication -by pass shunt and add scale. Excellent condition $ 1.25 5 for 5.00 ID 169 /APN -12. SCOPE INDICATOR complete with 7 tubes and CR tube 3 BPI. Brand New w /conversion instr 512.95 WRITE FOR LATEST FLYER R W ELECTRONICS 2430 S. Michigan Ave.. Dept. N Phone CAlumct 5 -1281 Chicago 16, III. REALIZE YOUR DREAM Become a graduate Electronics Engineer. Share rewards awaiting college men . . higher income, rapid advancement. Important firms interview seniors here regularly. Electrical Engineer in 27 months B.S. degree in Electrical l Electronics or Power major), ilechanical, Civil, Chemical, Arrinautical Engineering. Al 36 Months a B.S. in Business Administration (General Business. Accounting, MI dill- Transport Management majors). For earnest. capable students. Small classes. More professional class hours. Mature students. Well-equipped labs. :LLxlest costs. Ceteran approved. )'ear -round operation. Enter June, Sept., January. Mar. Write J. N. McCarthy, Director Admissions, for Catalog and "Pour ill Career in Engineering and Commerce" Book. 144 1659 College Avenue, Angola, Indiana i Low -Level Clamp Modulator (Continued from page 61) power of approximately 255' of the peak modulated value. Not only is the efficiency of the final stage higher with this adjustment, but also there is less detrimental effect to the operation of a.v.c. systems at the receiving end. Transmitter Adjustments Any transmitter incorporating the design provisions previously outlined can be adjusted for proper operation of the low -level clamp modulator by following the step sequence given below. In medium- and high -power transmitters, the customary provision should be made for reducing power input to the final during initial tuneup. Other than a dummy antenna load for the transmitter output and the shack receiver or a crystal detector for checking audio quality, no special equipment is required to make the necessary tuning adjustments. As in the case of the antenna, the dummy load used for tuning should be capable of loading the transmitter to at least 75% full output for best depth of modulation. 1. With the dummy antenna connected and the clamp modulator switched out of the circuit (to c.w. position), peak up the tuning of all stages for maximum power output as for c.w. operation, making a note of the final amplifier plate current reading. 2. Switch the clamp modulator into the circuit and observe the final amplifier plate current reading (with no audio fed into the modulator). If this reading is approximately 25% of the maximum reading obtained in Step 1, no further r.f. adjustment should be necessary and the audio gain control should then be set so that sufficient audio is available to swing the final plate current to the maximum reading of Step 1. The audio gain control should then be backed off slightly and the transmitter is ready for operation. 3. If the plate current reading obtained in Step 2 is greater than 25%, detune the final grid circuit slightly to reduce the current to the desired value. This should require very little detuning. If, however, insufficient reduction in current is obtained by only slight detuning, then increase the resistance setting of the driver grid resistor (R5) until the proper reading is obtained. If the reading is still too high, indications are that stray coupling exists between the exciter and final or that there is too great an excess of drive available to the buffer. This can be reduced by lowering screen voltages on the exciter stage or stages. 4. If the plate current reading obtained in Step 2 is zero, or much less than 25% of maximum plate current reading, carefully touch up the tuning controls to see if the desired value can be obtained. If the plate current is still far below the desired value, reduce the resistance setting of the driv- v-flectric OWER CONVERTERS Give You 110 A.C. HOUSE CURRENT ANYWHERE You Drive or Cruise 'Thief": 75.125 watts 6 or 12 v. batteries. 64 9S Other models from 15 to 200 watts, with prices as low as 512.95. NO INSTALLATION Just plug into cigar lighter on dash of car, truck, or boat -and away we go OPERATE PORTABLE TV, SMALL DO -IT- YOURSELF TOOLS WHEREVER NEEDED One of the great conveniences of our electronic age 101 USES V`°' sF.qAY DICTATION ALL ELECTRIC DO -IT- YOURSELF SHAVERS HOBBY TOOLS See Your Electronic Port, Deoler or Jobber COMPANY DESIGNERS L MFRS. OF ELECTRONIC EQUIPMENT SINCE 1927 1058 RAYMOND AVE., ST. PAUL 14, MINNESOTA IN CANADA ATLAS RA010 CORPORATION LTD. -ONTARIO ** * * * *** * ******** *** * ** ** 0 -500 M arkedps (Basie Movement) 3t/ Aircraft * Meter. Marked fuel Air Ratio mid. by Cam * bridge instrument. 2 for 3.001 1.59 ea. * * * * * * * * * * * * * * * * * * * * * * * * ** Heavy Duty Power Trans PRI. 220 Y GO eye Iran ne tapper) fur 115V. S.. :1800 \'('T /850 MA. MN. 1 W. E. Co. 85. h x O IC. x D d 15.95: 2 for 30.00 POWER TRAN% PRI. 115V or 220v 00 eve. See. 1400. \'('T 300 MA !Conservative) 11.8v -4:\ /01k10-I A '5V-IA. atfd. by W. E. ('n. Body Dim 7 21/ 12 I, x O 2:1132 Inc. 5 15' I0 wd. . ..7.95; 2 for 15.00 HEAVY DUTY CHOKE. 137 Ii,' .1',0 MA ,nooMA Conservative. 3.10I . Merit. :I 1I \'il`.1,s 1211 ld'll ..6,95 Radio TRANSMITTEY T- 5!t('IsNt- . New 14.95 PLUG -IN TUNING UNIT. A unit or Model 01'-7 F're, Range SOO -1500 KC ............ New 4.95 GLOSAR lane in,ltletive resistor non ohms iiS w'ntl r:. ........... .98 ea. 12 for 10.00 PORTABLE AMPLIFYING MEGAPHONE. Complete w/ electric :aplp I ,tlel ,cent iii",,I 0101 ieì'''or swittrn 0,,1411,ím) thnnd tiOrrnpl and ....Itch portable tripod stand , r ,t,d,. amplifier and 1v Der, FIL . ......Rond New nt FILTER CHOKE- 511 \',))' f "1 ah--- U('- 9l PUT 20011 l r.a (small ttlermih ...... 9.95 SORE SON Rr.«ULATOR npu lei -5-1 l0 19.05 SORENSON REGULATOR-Input 1 -f5 -1:10 volts .95 t 1 1 7 at t 1 . . XvA.Y . . . . i1í,,1 29.95 VERTICAL FLIGHT GYRO type ('-1 Antnpilot...29.93 #***********************- * 9C -645 XMTR RECEIVER WITH 19.95 * Control Bos Fos Above .. BRUIT ND NEW) Ií 49 * PE -101C DYNAMOTOR BRAND NEW S.9S * * * * * * * * * * * * * * * * * * * * * * ** * VARIABLE CAPACITOR. Glass Dielectric Conn, -n trie Tem.. 1di MMyit 6 for 1.00; 100 for 15.00 2API Who e,.rket 1 95 DYNAMOTOR- EICOR. n Volts itecutput . GUOi 150 NIA. ...... .NEW 6.95 -2 for 13.00 POWER SUPPLY UNIT 1'F: 110 -8 117V 1111 eve. a ceO Like \ew 49.95 TEST HSET aTS 5 4c /nu EAU/ .,,,.x, n-,, T m, CC-652 Recel 'r Manual.... ..39.9E ät832 Ken1,' er 2 time w tu,I, ,.,n.l.ik, peu 14.95 Sass 'l'ul,.s A Ri Good a'u 1.95 BC-1]OB Hev Complete ,,,.., w'........29.75 110-6 x5' ('W lait i Freq. tale. Meter IOU -1 f8 nie Comprises (rampglsIs , se,i Brel. r yslalc,mlolled os for calibrating Ita24.95 RM'52 t... 5 5 5 5 . SI Rhone CONTROL UNIT Trans anx used f"r '.'R Phone match circuit ine Air. w' 1.95 rat, Pilot formation el irk V. R. Air Yree s 1 OL remote asis o,l, 5.95 DROPPING VOLTAGE Resistor 12 to 6 volts 125 New 98e CAVITY PC -1132 w 7218 The.........Nosy 1.98 AUDIO TRAN( cumul Pr) 55011 ohm Sec cl 15. N. 4 ohms fully Included 1 13 'Ici s - p v . 1 1:1'lÚ . wl INDICATOR orGHTS Istie type +t 17-elt 049 w built in resistor for \ew S9C, 2 for 1.39 TELEGRAPH KEY J -47 . .............. \ew mf:mnty rrb,. -Write LARGE QUANTITY OF LATEST COMPONENTS IN STOCK SEND LIST WILL QUOTE -LARGE OR SMALL SP ' KS RADIO SUPPLY 194 GENESEE ST.. BUFFALO 3. N.Y. PROMPT DELIVERY ASSURED ELECTRONICS WORLD

..569.95 1 General : Circuit er grid resistor t:: necessary plate current is obtained. Failure to obtain the necessary plate current at this point indicates insufficient drive to the buffer and exciter voltages or interstage coupling should be increased accordingly. Advantages of System Aside from the prime advantage of economy in components and space, which is offered by the conventional clamp systems described in the past few years, the low -level clamping system dissipates negligible power even when used to modulate transmitters with outputs up to the maximum legal limit. Other clamp tube circuits are quite wasteful of power, especially when used to modulate high -power amplifiers. An outstanding feature of this system is that despite its use as a low - level modulator, it is impossible to overmodulate the transmitter and cause sideband splatter. Another feature is that, since the plate current of the buffer and final amplifier stages averages about half the maximum value required for steady input modulation (due to the character of speech audio), it is practical to operate these two stages at plate inputs of 50'7r or more above manufacturers' ratings, without damage to the tubes. Thus, a kilowatt input can be achieved with smaller tubes than usual, an example of which is shown in Fig. 6. -3p- MARS SESSION FOR MAY TIlE following scss' . hate been seheduled by MARS for the month of May. 'l'he First U.S. Army MARS SSB Technical Net, Wednesdays at 9 p.m. (EDT) on 4030 kc. upper sideband, has listed the following speakers: May 6 - "American Antarctic Communications Adventures" by Amory H. Waite, Jr., Project Engineer, U.S. Army Research & Development Lab., Fort Monmouth, N. J. May 13 - "Telemetering for Guided Missiles" by J. R. Popkin-Clurman, W2LNP, Telechrome Mfg. Corp. May 20 - "The Megaender" by Ilarry Kihn, Technical Staff, RCA Laboratories. May 27 - "Novel Tuning Methods at UHF & Lower Microwave Frequencies" by Bernard D. Nadler, Lewyt Mfg. Corp. The net will recess until September upon completion of the May series. * * * THE Air Force MARS Western Technical Net, Sundays front 2 -4 p.m. (PST) on 7832.5 and 3295 ke. and 143.46 me., has listed the following speakers for May. May 3 -"Organization Facilities & Operation of a Modern Communication System" by P. C. Christensen, Mackay Radio, San Francisco. May 10 - "Wide -band Microwave Telemetry" by Fred Barry, Equipment Development Div., Phileo, Palo Alto. May 17 - "High Impedance Modulation Systems for Klystrons" by Gene Tallmadge, Levinlhal Electronics Products Inc., Palo Alto. May 24 - "Electronics in Medicine" by Dr. J. Phillip Sampson. May 31 - "Equipment Utilization and Conversion Information" by USAF MARS Western Technical Net Members. May, 1959 With These Top Feature Points! Maximum legal input. Certified for FCOA matching funds. Third and filth order d,stortion products down in excess of 30 db. Passive grid circuit. 50 to 75 ohms input. Built-in r.f. output meter to simplify tune up. Complete coverage of 80 thru 10 meter amateur bands. Pi- network for maximum harmonic suppression. Variable output loading. All important circuits metered. Circuit breaker assures protection of power supply. 25 Hams to Serve You Top Trades Always Latest Serial Numbers Nation's Leading Lines in Stock for the really Big Signal I'd Recommend the hallicrafter's HT -33A s8000wn 5346° Per Me or 5795 00 Han, Net. Free 1959 Catalog lam packed with bargains - everything in Radio. TV, and Hi Fi - for Handyman, Ham, Experimenter or Serviceman! f "I's1 LEO: Please Send O Free Catalog, and Quote Top Trade 5 uDIT PINSOMl..ZID RIC TRON, ) tT MOUSI for my on the HT -33A ` . tavd Padcó LABORATORIES PH 2 0277 W e0OADwAY COUNCIL SLUMS IOWA Name: Address SURPLUS BUYS City b State' 00 MOBILE -12 Volt Dynamotor to nt In Glove Compartment area. 7" x aa4" 11 -10 It,,. tn- 12VIO- 011t- 4O0VUC -1H11 Mil ,Constant Dutyl. ..New 37.95 NI -PAR SEAMS 61A5 -: Element-0 :Meter Ban, -Over IODR In. Proven results-nn,, Ins. ..........514.95 2M 6-O element -2 Meter Beam -Over 1t)DII ].00 LJ6-O f:lem11nt__o Meter Long John -Over 1308. 15 Ins. . 34.95 I 6 Nalo -O Meter Mobile Antenna Curler 2 Inc. 15.95 2M Halo -2 Meter Mobile. 1 In. with Tele rope Mast 9.95 HEWLETT PACKARD VTVM 7400A- riper ..569.95 ONMITE DUMMY LOAD - 0100 -500 Ohms lin.w I NEW 51.00 Ea. DOE. 510.00 TS -162 RE Signal Ge,. I .Scope. 115V- no e i- M' Tones and Schein. Gaul II Cond. 50 1-ns. ..519.95 11C- 221- Fee,I. Meter W rnrig. Boot. Kral. . I TRANSFORMERS --60 CYCLES 115V T 1 -See. .1-900 e'iT 1177 Ma. Can ,Iraw.:1110 Dla - 2- 8.3 -8A: Sere _:I-'r.OV-2 A. Ilene g Sel- 5 "x57x47 R[% Special SS.95 T2 -pee. S i- 8(1oVCT 1150 Ma. Can draw 2 5 , Ma see. /.2-0.3V-4A. See. t73- 5.0V-:1A" TI, N REX Special S5. 75 -2a0V. T -3 -See. i :I -Inn0 VCT. 2110 Ma. ul 5-x4^x:l^ R[% Special SI 9 T4 Pri. See. 2.5V- I0A -1n Kv. In._ 53.95 T -5-2505'. Prl. Sec. 6.3V- 20A- 4- x4-x3n.i" $5.95 T- 6- 2:10V. Pei. See. 5.0 -10A 4 Cube ....33.95 T -7-Sec. 300-0-:100V 1110 Ma.: 12.11VtT -:IA. 12.01' -3A: - 1)5' -:IA. Open Frame- Cu n,mPa,'I -Useful as 12 or 24v. Trsf. nn for Sulu. Gear. $2.49 CHORE -le) Hy 2 50 Ma. 4" Cline $1.95 1 OIL CONDENSERS 600VDC 1.000VDC 2.000VDC 000VDC 151015 .40 1M8 S .80 IMIO S as IM /tl 5.3.50 1.50 2 - 6.25 .75 " 2.35 3.50 4 " 13.95 e .95 10 " 2.50 8 6.00 Full Range lo " 1.15 IS 3.30. Sizes Avail. MINIATURE M 11/2" SO. Original Sealer 0-100 Dlieruamps $3.95 0 -500 DDeroann,s 52.95 ALL NEW. BOXED I VARIABLE CONDENSERS W /SHAFTS 25 Mmfd- ,Hlunman 2 for 51.00 35 Mmfd- Ulammari 2 for 1.00' 140 Mmfd- ,Ilammari 3 for 2.00 split Stator Dual :150 5Unf0 1 I:V S2.95 I 2 " C.R. TUBE _API -New IT..v, -0 $1.95 REX RADIO SUPPLY CO. 88 Cortlandt St. New York 7, N. Y. In the Heart of New York's Radio Row a I ' comprehensive home study courses in ELECTRONICS ENGINEERING F:ne11 rs, I w. rit ten b y an - I t tn lh, - ' i 1 his field all 41 1,inclue hen the Mt i ndard r ognixe,l 111.m oL6. l'eraonal anti individual III lenliml given to Ille student 11 II M r r d method of i I ruction. nlplete informaand , .vIL,Ìn.. o f each ech ,our c, tile 1iip, n. - - Choose front among t hest. complete courses Advanced Radio and Electronics Engineering Electronics Engineering General Radio Engineering Radio Servicing, Maintenance and Repair Television Television, Maintenance and Servicing General Technical Training Special Advanced Electrical Engineering Course for Professional Engineers Examination Electrical Engineering Electrical Installation and Wiring Electrical Draftsmanship Mathematics ' Electricity Supply Telephony Canadian Institute of Science d Technology Ltd. 723 Century Bldg., 412 5th St. N.W., Washi ngton, D. C. Gentlemen: Please laniard free of cost or obligation information on your Electronics Engineering Courses. Name Addreee City State In Canada: Canadian Institute of Science and Technology Ltd., 723 Garden Building, 263 Adelaide St., West Toronto 1, Ontario 145

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