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1 DIRECTION FINDING AND DF RECEIVERS page 238 Journal of the Radio Society of Great Britain A nn uuncing another wu rid beater THE NE W K W 200 0B • T W O-SPEED VFO DRIVE SSB TRANSCEIVER: 180 watts P.E.P. IMPR OVED VFO READ-O UT 10-160 Metres complete with AC PSU, VOX, e P.T.T., I.R.T I.T.T. • NE W, PRECISE METERING plus the usual KW Quality and Reliability e ATTRACTIVE PANEL LAY O UT Other KW Products: Write for illustrated detailed specifications on the KW 2000B: KW K W Antenna Switch Atlanta: KW Vespa Mk 11: KW 201: KW 1000 and our list of KW 13 positioni KW E-Z Tested Trade-ins. Antenna Match Unit, K W PEP Meter, KW Match S WR Indicator K. W. ELECTRONICS LIMITED K W Low-Pass Filters, K W Trap Dipoles, K W Balun, K W Du m my 1 HEATH STREET, DARTFORD, KENT Load, K W Q Multipliers ELECTRONICS TELEPHONE: DARTFORD 25574. CABLES: KAYDUBLEW DARTFORD LIMITED RA DID [11111111 uPlc!!!!!!!! ASSOCIATE EDITOR John J. Adey 233 CURREN T CO M MENT —BRUSSELS 1969 EDITORIAL ASSISTANT Laurence S. Margolis, G3U ML 235 JOHN CLARRICO ATS, OBE, JP, G6CL AN APPRECIATION EDITORIAL PANEL 236 QTC J. P. Hawker, G3VA G. R. Jessop, G6JP 238 DIRECTION FIN DING AND D„F RECEIVERS R. F. Stevens, G2BVN Robin J. Pearce-Boby, Dipl. Arch.(Oxford), ARIBA, G3JLE 245 NE W PRO DUCTS DRAUGHTS MAN Derek E. Cole 246 REM OTE CONTR OL FOR VHF APPLIC ATIONS Robert K. MacDowell, W4VGS G5AFL ADVERTISING 250 EQUIP MENT REVIE W —KNIGHT KIT G-30 GD O AN D MANAGER KG 625 VALVE VOLT METER Mrs P. D. Harvey D. W. Robinson, G3FMT EDITORIAL 252 QSL CORNER OFFICE A. O. Milne, G2MI RSGB Headquarters 253 THE MOSVED AN D THE DIRECT GENERA TION OF SSB 35 Doughty Street, Henry Gibson, K5MM W.6 London, WC1 254 TECHNICAL TOPICS 01-837 8688 Pat Hawker, G3VA ADVERTISING 259 THE INVESTIGATION BY THE POST OFFICE OF RADIO OFFICE AN D TELEVISION INTERFERENCE FRO M A MA TEUR Sawell and Sons Ltd., TRANS MITTING STATIONS 4 Ludgate Circus, London EC4 260 MONTH ON THE AIR ELE 4353 John Al'away, G3FKM 262 PROP AGATION PREDICTIONS 266 FOUR METRES AN D DO WN Jack Hum, G5UM 272 SOCIETY AFFAIRS RADIO COMMUNICATION 273 AN NU AL GENERAL MEETING (INCORPORATING THE RSGB BULLETIN) 274 OBITU ARIES IS PUBLISHED 275 RADIO AMATEUR EMERGENCY NET WORK BY THE RADIO SOCIETY S. W. Law, G3PAZ OF GREAT BRITAIN AS ITS OFFICIAL JOURNAL AND 276 CON TEST NE WS POSTED TO ALL MEMBERS 280 CLUB NE WS ON THE FIRST TUESDAY IN EACH MONTH 284 LOOKING AHEA D, CONTEST DIARY AN D MOBILE RALLIES RADIO SOCIETY OF GREAT BRITAIN, 1969 285 ME MBERS' ADS 295 INDEX TO ADVERTISERS CLOSING DATES (except where otherwise staled) MAY 10 APRIL APRIL 1969 JUNE 5 MAY VOLU ME 45 No. 4 INDIVIDUAL COPIES 4s, LO WE ELECTRONICS 50/52 W ELLINGTO N STREET, MATLOCK, DERBYSHIRE. DE4 3GS. Tel: Matlock 2817 (2430 evenings) Let's fill a page with moans this month. I'm in a real old snarling mood. I also have the FT-150 in stock. At £215.0.0. complete with both mobile 12v Mainly because some London spin robbed me. Their advertising reads "all and mains p.s.u.'s built in. it represents extremely good value. It's big goods are new, first quality manufacture only and subject to makers full brother the FT-500 with a 500W pep. input costs £250.0.0 complete with guarantee. - Fair enough. I think, in my simplicity I order some 0C171's. built-in mains p.s.u. "Funny" I thought when I got them ''OC171's should be chunky efforts For someone wanting something a little cheaper, take a close look at the with 4 bits of wire, whereas these are stamped 0C171, sure enough, but Inoue. The receiver is all transistor using lots of FET's around a top quality only 3 wires and a TO5 case". VERY INTERESTING, New they may be. 9 mc/s xtal filter. A very sensitive, quiet, birdie free Rx. 12v d.c. or 240v a.c. first quality manufacture they may be. subject to makers full guarantee supplies built in. It's a little beauty and comparing it with other Re's around they may be. but 0C171s they most certainly are not! Ah, well, that's the the price, well worth £85.0.0. The companion Tx uses the Rx V.F.O. for last time I deal with that outfit, you can bet your sweet bippy. Unfortunately transceive operation. Again transistor except V.F.O. mixer, driver and PA the laws of libel prevent me from warning you against a bunch of spivs (2-6146B's). A nice sounding very clean Tx complete with psu L95.0.0 publicly. In my case, it was O.K.—I only wanted them for a fool-around Where you'd get a better rig for £180.0.0 complete, I honestly know not. project. But think of the thousands of mugs who don't know enough to Here again, let's introduce some plain honesty. Is the Rx as good as the realize they've been done. Some poor lad who can't figure out why his Sommerkamp FR-500 I'm always asked—of course it isn't. If it were, then transistor converter or something is dead. Ah. well, one lives and learns I wouldn't sell a Sommerkamp. Certainly it is better in some respects, but Let me just add that if you too have been caught—write to (a) MuIlard, it just hasn't the versatility of the FR-500. However, taking other transistor who are ready to take a swipe at the spivs. and (b) Wireless World, who, gear on the market at around the same price as the Rx, there just isn't any provided enough people shout, will stop their advertising. I can't understand comparison. the mentality of these crooks—it's just as easy to make a living honestly. The Star 700 series also represents excellent value for money. SR-700 Rx at As I said, I'm in a snarling mood, ready to take a swipe at anyone—particu- [115.0.0. and ST-700 Tx at [135.0.0 larly advertisers who claim perfection for things which are very, very far Last good buy is the National 200 at [145.0.0 less p.s.u. I just can't sell these from perfect. It constantly amazes me that people can be fooled by such blah. and I don't know why. It is one hell of a good rig for the money. It is not, What really riles me is that the advertiser is taking us for mugs. His opinion of course, in the same class as the Sommerkamp transceivers—but it's nowhere near che price either. I just can't understand you chaps. The only of us chaps who read this magazine is so low that he thinks we haven't the intelligence to see through it. And that gets me mad. Once again, the laws thing I've got against it is that it uses the PA pi net as the Rx input stage. of libel stop me from blowing my stack, but honestly, lads, just look at the Now. the PA tubes' load impedance differs very considerably from the r.f. ads and the deliberate attempts to fool us. Here again, readers of this amp. input impedance, to say nothing of conflicting Q requirements so it magazine should know something of spec sheers and how they can be isn't really very elegant design. However. Gentlemen, just take a look distorted, but what about the poor chap who laps it up as gospel—he's done around and see all the other makes at much higher prices that do exactly proper, as they say. Most of us know what constitutes a mechanical filter, the same thing! Also, by the way, look at Som merkamp who DO NOT do we know the difference between a spec which claires 2.4 keis selectivity and it—they use proper r.f. antenna coils for the Rx side. Just one of those little one which says 2.4 kcfs at -6dB at 4'5 kcis at 60dB. We know the differ- things the spec. sheet never mentions! And of course. just one of those little ence between so many microvolt sensitivity for 10dB S/N ratio and better reasons I flog Sommerkamp and not some other brand! However, in spite of than so many microvolts for 10dB SjN ratio across the entire tuning range. this, the National 200 is value for money and that's my criterion. I honestly We know the importance of image rejection, internally generated signals, chink that the above stuff is top value for money, but more than this, you stability etc. and do our best to find these things out. But what about the get service second to none. Also of course, it is all ex stock at the time of poor laddy who doesn't know. All he thinks is, it's widely advertised and writing. everyone sells it, it must be good. Poor lad, he's a lot to learn. When some- Anyway, so much for the new expensive stuff. In the second hand line I have thing new comes on the market, I try it out. If the maker claims 2 kc,Is a very good selection of good quality stuff.