A TWO VALVE PORTABLE RADIOGRAM 1 sg, - CONTENTS A SIMPLE INTER -COM INCREASING T.R.F. SELECTIVITY A MICROPHONE PRE -AMPLIFIER A TRANSISTORISED SIGNAL GENERATOR FURTHER MODULATION ASPECTS www.americanradiohistory.com PRACTICAL WIRELESS March, 1958 C.R.T. ISOLATION TRANSFORMER CHAMPION VHF (FMI TUNER, Type A. Low leakage windings. Ratio 1:1.25 88 -96 me /s. giving a 25/, boost on secondary . 5 Mullard valves and superhet tuning heart. ; 4 v. ; 6.3 v., 10/6 ; 10.8 v.. 10/6 10/6 Maroon and cream receiver styled cabinet. 10,6 ; 13.3 v., 10/6. 12 u u x tiln. FMlures: This ie a self -powered Ditto with mains primaries, 12/8 each. 200/250 t. C VHF (FM) Adaptor with Mains 221/740 t vt Type B. input volts. Multi opensting and servicing data and a screened Output 2, 4, 6.3, 7.3, 10 and 13 volts. Input lead for connect- to pick -up sockets ut any has two taps which increase output volte by radio, radio-gmm or amplifier. 25';, and 50% respectively. Low capacity brand flew with 12 months'iths' guarantee. List imitable for most Cathode Ray Tubes, 211 - Ditto for 6 v. C.R. Tubes only- 17/0 price, In gee Our price. ..arr. 416. Type C. Low capacity wound transformer for 10 gns., of 81 use with 2 volt Tubes with falling emission. Term+: l lepe oit £8 and 6 monthly payments Input 220/240 volte. Output 2.2 }02} 21 -3 volts at 2 amps. Tag Panel, 17/6 each. With 1958 RADIOGRAM CHASSIS Volume Controls t COAX NOTE.-It Is essential to use mains primary 80 ABLI. WAVEBANDS. FIVE VALVES Long ol,imllee. Unarm- spaced Poly- types with T.V. receivers having series- THREE connected heaters. S.N . n; nr.-50 m. LATEST MULLA RD teed 1 year. Midget thene insulated. }in. dia. M.W. 200 m.-550 m. ECH42, EF41, EBC'41, 10,00)) ohn,e to 2 Meg. Stranded core. No Sw. Losses 4 yd. TRIMMERS, Ceramic. 30, 50, 70 pf., Od. ; 1011 pf. L.W. Mgt m.-2,000 ni. EL41, EZ40 O.l'.tlw. D.P.Sw. cut 50, d C 150 113 ; 250 pf., 1/6 ; 500 pl., 750 pf., 19. 12 -month guarantee. 3 - 41- 4!9 Fringe Quality pl, 1 RESISTORS. Preferred values, 10 ohms to 10 meg., A.C. 200/250 v. 4 -way Switch ; Short- Medium- Linear or Log Tracks. Air Spaced, / yd. } w.. 4d. ; 8 w., 4d. ; 1 W., 8d. ; 1/ w.. 8d.: 2 w., 1/ -, l.ongGram. A.V.C. and Negative feedback 58 x Glass Dial COAX PLUGS... 1/- DOUBLE SOCKET 1;3 HIGH STABILITY. w., 1 %. 2 / -. Preferred value. 4.2 watts. Chassis 13f x 21ín. i SOCKETS . 1.- OUTLET BOXES ... 4/6 100 ohms to 10 x 48ln., horizontal or vertical available. 10 meg. Ditto, 6 %, 9d. BALANCED TWIN FEEDER yd. Bd, 80 or 300 ohms. 5 watt WIRE -WOUND RESISTORS 2 Pilot Lamps, Four Knobs, Walnut or Ivory. (1/3 DITTO SCREENED per yd, 1/ -, 80 ohms only. 10 tt> 25 ohms-10,000 ohms { 1i6 Aligned and calibrated Chassis Isolated from mains. WIRE -WOUND POTS. 3 WATT. Pre-Set SI in. 15 watt 2/- 'p.v. Type. All values 25 ohms to 30 K., 31- ea. 15,000 ohms-50,000 ohms, 5 w.. 1/9: 10 w., 2/3. 10 gns. Carr. A Ins. 4/6. 4; -. (Carbon 50 K. to 2 m., 3/ -). WIRE -WOUND 4 WATT. Pots 25in. Spindle. 12/6 PURETONE RECORDING TAPE TERMS : Deposit £5.5.0 and six monthly payments of D. Values, lull ohms to 50 K., 5/8; 100 K., 8 /6. MATCHED SPEAKERS FOR ABOVE CHASSIS. CONDENSERS. New stock. .001 mfd. 7 kV. 1,200 ft. on standard 7" Metal reels. '1.12.12.. 5,8; Ditto, '20 kV., 9/8; 100 pf. to Suu pf. 8in., 17/6 ; loin., 25/- ; 12ín., 30 / -. 7" plastic 4/3, 7" metal, 2/3. Mica 6d.; Tubular 500 v. .001 to .01 mfd.. 9d.; .05, .1, 1, -; .25, 1 /6; á/350 v.. 1/9; .1/350 v.. 8d.; FERROYOICE Tape FOR 1,200ft. Plastie RECOMMENDED ABOVE .01/2,000 v., 1/9 ; .1 mfd., 2,000 volte, 8 /6. 25/- on Plastic Spools. CHASSIS CERAMIC CORDS. 500 v., .3 pf. to .01 mfd., 10d. * COLLARO * SILVER MICA CONDENSERS. 10% 5 pf. to 500 0/P TRANSFORMERS. Heavy Duty 50 mA., 4/6. pf., 1 /-; 605 pf. to 3,000 pf., 1/3. Close tolerance Multiratio, push -pull. 7/6. Miniature, 394, etc., 4/6 HIGH- FIDELITY AUTOCIIANGER Model RC458 ( } 1 pF.) 1.5 pF. to 47 pF., 1/8. Ditto, I% 50 1F. L.F. CHOKES 15 -10 H. 60/65 mA., 5 / 10 H. -; 71n., 101n., 12ín. Records to 815 pF., 1,8; 1,tó/0 pF. to 5,000 pi', 2 / -. 80 mA., ; 10 H. 150 mA., 8/6 1218. 18, 33, 45, 78 r.p.m, MAINS TRANS. 350 -0 -350, 80 ntA, 6.3 v. tapped. 4 SPEEDS -10 RECORDS l.F. TRANSFORMERS 7/6 pair. 4 v. 4 a., 5 v. tapped 4 v. 2 a., ditto 250.0- 250. 22/8. With Studio " 0 " pick -up 485 Ks,, Slug tuning Miniature Cm 2}ín, Bargain 300.0.300 65 mA., 6 v. 4 a., 4 v. 2 a., 15 / -, IN BOXES lin. x High Q and good bandwidth. TRANS. Tapped prim., 200 /250 v. 6.3 v. BRAND NEW MAKER'S lin. HEATER By Pye Radio. Data sheet supplied. 11 amp.. 7/6 ; tapped sec. 2, 4, 6.3 v., 14 amp., 8/6 OUR PRICE 19.115.0. post free prim. 230 v. Sec. 6.3 v. 2 amp.. 10/6. TER MS Deposit 65.5.0 and six Wearile M800 IF 485 Ka s 12 6 per pair. ALADDIN FORMERS and cope, lin., 8d. ; fin., 106. 0.3in. monthly payments of £1. FORMERS 6837/8 and Lana TVl /2. lin. eq. z Space required 141n. X 121in. 5ín. NEW ELECTROLYTICS. FAMOUS MAKES 2in. and tin. eq. a 1 In., ea., with cores. 2/- above and TUBULAR CAN TYPES TYANA. -Midget Soldering Iron. 200/220 v. or 3in. below. TUBULAR 1/350 v. 2/- 100/25 v. 21- 8 +16150u Y. 5 e 230/250 v., 18/9. Solon Iron. 24/ -. Suitable Player Cabinets, 4918. Instrument v. 2/3 8 +8/500 v. 4/8 16 +16/500 v. 8.- MAINS DROPPERS. 3in. x 15in. Adj. Sliders, Amplifier Player Cabinets, 83/ -. 2/450 4/450 v. 21- 16 +10/500 v. 25 +20/455 v. 516 0.3 amp. 750 ohms, 4/3, 0.2 amp., 1,000 ohms, 4/3, 8/450 v. 5/3 6/. 32 +32/350 v. 418 CORD. .3 amp., 60 ohms .2 100 LINE per foot, amp., 8/500 v. 2/9 CAN TYPES 32 +32/450 v. 6/6 ohms per foot, 2 -way, 6d. per 3 per GARRARD 4 -SPEED SINGLE foot. -way, 7d. foot Clips 3d. 50 v. LOUDSPEAKER, P.M. square. RECORD PLAYER 4SP 16/450 v. 316 +50/350 7/- 8 OHM. Ziin. 17/6. 16/500 v. 4/- 16/450 v. 3/6 60 +100/350 v. 11/6 5in. Go0durans, 17/6. Tin. s 410. Goodman,, 21/ -. Brand new and fully guaranteed 12 months 32/450 v. 5/6 32/350 v. 41- 100 +3001275 v. 3 1In. Elac., square, 21/ -. Sin. Plessey, 19/6. 25/25 v. 1,9 64/350 v. 5/8 12/6 68in. Goodman.,, 101n. R. a A., 30 18/6. /-. 50/25 v. 1/9 500/12 v. 1,000 +1,000/6 v. TSL Tweeter. L,91175, 8/6. 121n. Plessey, AUDIO PEIRFE4'.TION 3/- 301 -. 50,5)1 v. 2/- 8 +16/450 v. 6/- 6/6 Sin. M.E. 2.5k field, tapped O.P. trans!., 24/8. 16, 45, 78 15 ohm Plessey 10 wt. 12ín. with Tweeter, 97/6. Designed to p ay 33, r.p.m. Records. SENTERCEL RECTIFIERS. E.H.T. TYPE FLY. CRYSTAL DIODE O.E.C., 2/ -. GEX34, 4/ 7in., 10in., 12in. Lightweight Eta/ pick-up, BACK VOLTAGE. K3 /25 2 kV., 6/ -; K3/40 3.2 -, separate sapphire HIGH RESISTANCE PHONES. 4,000 ohms, 1616 pr. GC2 turnover head, two styli, 7/-; 133 45, 3.6 kV., 7/8; K3/50 4 kV., 8/ -; Standard and L.P., each plays 2,000 records 8 50 c.p.e. 30"10 of above. MIKE TRANS ?. 50 ; 1, 3/9 ea. ; 100 i 1, Potted, 10 /6. for K3/1110 kV. 14/8. voltage, SWITCH CLEANER Fluid squirt ,pout, 4/3 tin. Voltage 200,150vs8A..C. MAINS TYPE CONTACT COOLED 25u v. 50 mA., 8,8; 230 v. 85 n,iA., 9/0 Selenium 300 v. 85 mA.. 7,6. TWIN GANG TUNING CONDENSERS. 365 pf. OUR PRICE 1 .0.0 wok. Post Free. miniature lin. x 1 8In. x 181n., 10/ -. .0005 Standard COILS Wearite " P " type, 3/- each. Osmur Midget Terms : Deposit £5 and 4 monthly payments " Q " type adj. duet core, from All ranges. th trimmers, 9/- ; leas trimmers, 81- ; midget, 7/6 ; 4/-. of D. Space required 14m. x 121in. 3in. L. dr Med. T.R.F., with reaction, SINGLE. 50 pF., 2/8; 100 pF., 71 -; 150 pF., 8 /8. TELETHON. 3'6. solid dielectric 100, 300, 500 pF., 3/6. above and 21in. below. FERRITE ROD AERIALS. M.W., 8/9; M. A L., 12, 6, SPEAKER FRET. Expanded Metal Silver, Amplifier Player Cabinets, 451 -, T.R.F.