MARCH 1978 40p Pickup arm design Memories Australia SA1.25 Canada $1.75 Denmark Kr.11.00 Germany Dm.4.50 Greece Dr.47.00 Holland Df1.4 50 Italy L. 1100 New Zealand SNZ1.50 Norway Kr.11.00 incl.mmris Singapore M $3.25 Spain Pros. 80.00 I) S A SI 65 www.americanradiohistory.com FREQUENCY MHz the difference is that it measures amplitude measure hum, distortion, modulation depth and all against frequency (instead of time). This comparatively sorts of things to an accuracy impossible on a 'scope - small change has led to our instrument being called a even on signals which 'scopes show as being 'pure'. "Spectrum Analyser" which, in turn, has caused oscilloscope users to believe it's for a completely different Our special digital store and television display job, "they are complicated things used only by boffins system gives you a steady 'infinite persistance' picture on and people concerned with light waves or something ". which you may also compare your ideal waveform with your actual live image. The graticule But - excuse us - that's is electronically generated - so no where they're wrong. Our TF 2370 parallax errors - and you can move AMPLITUDE is easier to use than many it up and down, or sideways, or oscilloscopes, it has a frequency expand it, all at the twist of a knob range from 30 Hz to 110 MHz and or two. gives much, much more information about waveforms of nearly all types Whether you are involved in than does a 'scope. And it has a design, production, calibration, built -in digital frequency meter and maintenance or indeed virtually any sweep (tracking) generator of its application where oscilloscopes are own so you can check amplifiers used, you will find that the TF 2370 and filters too. Spectrum Analyser will provide a faster, easier, more informative and Signals are displayed with the accurate answer to nearly all your fundamental, harmonics, sidebands questions. f and spurious content all clearly THE OSCILLOSCOPE THE SPECTRUM ANALYSER DISPLAYS THE SUM OF DISPLAYS THE DISCRETE and THE FREQUENCY FREQUENCY COMPONETS. a indicated quite distinct from COMPONENTS. If you're still sceptic ask us each other. You can see the for literature or, better still, ring waveform as it really is and us for a demonstration. 1111 MARCONI INSTRUMENTS Marconi Instruments Limited Longacres St. Albans Hertfordshire England AL4 OJN Tel: (0727) 59292 Telex: 23350 Marconi Electronics Inc 100 Stonehurst Court - Northvale New Jersey 07647 USA Tel: (201) 767-7250 Twx: 710 -991 -9752 Marconi Instruments 32 avenue des Ecoles 91600 Savigny- Sur -Orge France Tél: 996.03.86. Télex: 600541.F Marconi Messtechnik GmbH 8000 Munchen 21 Jorgstrasse 74 West Germany Tel: (089) 58 20 41 Telex: 5 212642 WW-001 FOR FURTHER DETAILS A GEC -Marconi Electronics Company www.americanradiohistory.com WIRELESS WORLD MARCH 1978 wireless wireless world ELECTRONICS /TELEVISION / RADIO /AUDIO MARCH 1 978 VOL 84 NO 1 507 Front cover shows part of Afghan- istan imaged for land resource map- ping by Landsat satellite and sent by radio to NASA receiving station. 33 Electronics and unemployment IN OUR NEXT ISSUE Cassette -deck calcula- 34 Loudspeaker coloration tor programmer enables by D. A. Barlow a simple, four -function calculator to carry out complex functions under 38 News of the month the control of a pro- The Crown and the Home Office / Racal trial results / gramme stored on an or- Defence research dinary audio cassette. Microwave landing sys- 40 World of amateur radio tems. ICAO will take a decision in April on the system to be adopted in- 41 Audio amplifier design ternationally. This article by P. J. Baxandall will describe the several competitors, together with some background on the subject. 46 IEA '78 Also in the April issue will be the last in the series of 47 Logic design articles by S. Fedida on Vie wdata- by B. Holdsworth and D. Zissos Current issue price 40p. back issue 53 Letters to the Editor (if available) 50p. at Retail and Digital electronics lacks sound theory/ Phase -filtering with time reversal/ Trade Counter, Paris Garden, Lon- The ear in phase audibility don SE1. By post, current issue 55p. back issues (if available) 50p, order and 56 Stereo coder payments to Room 11, Dorset by T. Brook House, London SE1 9LU. Editorial & Advertising offices: Dorset House, Stamford Street, 59 Circuit Ideas London SE1 9LU. Cross -coupled transistor bridge T elephones: Editorial 01 -261 Multiple station two -way intercom Programmable strobe 8620. Advertising 01 -261 8339. Telegrams /Telex: Wiworld Bis - nespres 25137 BISPRS G. Cables: 63 Analogue gate applications Ethaworld, London SE1. by J. Carruthers, J. H. Evans, J. Kinsler and P. Williams Subscription rates: 1 year: E7.00 UK and overseas 018.20 USA and Canada). Student rate: 1 year, E3.50 UK 64 Broadcast frequencies and overseas (59.10 USA and Ca- nada). Distribution: 40 Bowling Green Lane, London EC 1 R ONE. 65 Integrated-circuit memories Telephone 01 -837 3636. by John Dwyer Subscriptions: Oakfield House, Perrymount Road, Haywards Heath, Sussex. RH16 3DH. 73 Pickup arm design techniques Telephone 0444 59188. Sub- by Tejinder scribers are requested to notify a Singh Randhawa change of address. USA mailing agents: Expediters of the Printed Word Ltd, 527 Mad- 77 Microcomputer design ison Avenue, Suite 1217, New by P. Pittman York, NY 10022. 2nd -class postage paid at New York. IPC Business Press Ltd, 1978 83 A basic radio telescope ISSN 0043 6062 by J. R. Smith ibpa ABC mnaW Batn 85 New Products , B,vnror, www.americanradiohistory.com 2 WIRELESS WORLD MARCH 1978 vrirato, 41!Mi O. 4e For high quality electronic valves, The world over - semiconductors and integrated circuits - and the speediest service - specify Haltron. It's the first choice of You get the Governments and many other users throughout the world. Haltron product best quality and reliability are clearly service confirmed. The product range is very, very wide. And Haltron export from Haltron expertise will surely meet your requirements. Wherever you are, get the best service. From Haltron. Hall Electric Limited, Electron House, Cray Avenue, St. Mary Cray, Haltron Orpington, Kent BR5 3QJ. Telephone : Orpington 27099 Telex: 896141 WW -072 FOR FURTHER DETAILS www.americanradiohistory.com WIRELESS WORLD. MARCH 1978 3 LOW COST TESTERS LEVELL PORTABLE INSTRUMENTS INSULATION TESTER TRANSISTOR TESTER A logarithmic scale covering 6 decades is used to display Tests bipolar transistors, diodes and zener diodes. Measures either insulation resistance or leakage current at a fixed leakage down to 0.5 nA at 2V to 150V. Current gains are stabilised test voltage. The current available is limited to a checked from 1 µA to 100mA. Breakdown voltages up to maximum value of 3mA for safety and capacitors are 100V are measured at 10µA, 100µA and 1 mA. Collector to automatically discharged when the instrument is switched emitter saturation voltage is measured at 1 mA, 10mA, 30mA off or to the CAL condition. The instrument operates from a and 100mA for I C/I B ratios of 10, 20, 30. The instrument is 9V internal battery. powered by a 9V battery. RESISTANCE RANGES TRANSISTOR RANGES (PNP OR NPN) 10M D to 10T O (10" 0) at 250V, 500V, 750V and 1kV. &,l 10nA, 100nA,1 iA,10NA and 100µA f.s.d. ICBO E B O : 1M 0 to 1T 0 at 25V, 50V and 100V. acc. ±2%f.s.d. ±1% at voltages of 2V, 5V, 10V, 20V, 30V, 40V, 50V, 60V, 80V, 100V, 100k 0 to 100G 0 at 2.5V, 5V and 10V. 120V, and 150V acc. ±3% ±100mV up to 10k0to10GOat1V. 10pA with fall at 100pA < 5 % +250mV. Accuracy ±1 5% +800 0 on 6 decade logarithmic scale. BVCBO 10V or 100V f.s.d. acc ±2%f.s.d. ±1% at Accuracy of test voltages ±3% ±50mV at scale centre. currents of 10µA, 100µA and 1 mA ±20 %. Fall of test voltages < 2% at 10µA and < 20% at 100µA. 10nA, 100nA,1 µA ...10mA f.s.d. acc. ±2% Short circuit current between 500µA and 3mA. f.s.d. ±1% at fixed I E of 1 µA, 10µA, 100µA, CURRENT RANGE 1 mA, 10mA, 30mA, and 100mA acc. ±1%. 100pA to 100µA on 6 decade logarithmic scale. hFE 3 inverse scales of 2000 to 100, 400 to 30 and Accuracy of current measurement ±15% of indicated value. 100 to 10 convert I B into h F E readings. Input voltage drop is approximately 20mV at 100pA, 200mV VBE: 1V f.s.d. acc. ±20mV measured at conditions at 100nA and 400mV at 100µA. on h F E test. Maximum safe continuous overload is 50mA, VCE(sat)' 1V f.s.d. acc. ±20mV at collector currents of MEASUREMENT TIME 1 mA,10mA, 30mA and 100mA with I C/I B selected 10, < 3s for resistance on all ranges relative to CAL position. at 20 or 30 acc. ± 20%. < 10s for resistance of 10G f2 across 1 µF on 50V to 500V. DIODE G ZENER DIODE RANGES I As I transistor ranges. Discharge time to 1% is 0.1 s per µF on CAL position. D R E B O Vz: Breakdown ranges as BV RECORDER OUTPUT C B O for transistors. 1 V per decade with zero output at scale centre. ±2% VDF 1V f.s.d. acc. ±20mV at I D F of 1µA, 10µA, Maximum output ±3V. Output resistance 1k O. 100µA,1 mA, 10mA, 30mA and 100mA. typeTM14 £120 typeTM12 £ 110 Prices are ex -works with batteries. Carriage and Packing LEVELL ELECTRONICS LTD. extra. VAT extra in U.K. Optional extras are leather cases Moxon Street, High Barnet, Herts.