TEN FEET HIGH

Hokitika Guardian, 21 December 1931, Page 2

TEN FEET HIGH

WORLD’S LARGEST VALVE. MADE IN ENGLAND. Reluctant thought the rest of the world may be to admit it, it is an incontrovertible fact that the first valve circuit ever hooked up for radio reception was thought out and b:ought out by a British scientist, „ working in Great Britain, says a writer in an English radio journal. It happened in 1904, and Dr P. A. Fleming, of University College, Londonj was at that time the only man in the world who had tried out a valve circuit for wireless reception.

• "It ; ,.is . particularly fitting, then, that the absolutely last word —the wonder valve of the whole world — should belong also to Britain. It stands more than ten feet high, and it weighs over a ton! Evidently it is not the sort of valve you would think of using for your set. And even if someone kindly gave it to you, you would certainly need a new accumulator to run it, for it requires a filament current of live hundred amperes. Moreover, not only is it the biggest valve in the world, s but is is of a type hitherto almost unheard of.

As no dciubt you have ghessed, it is a transmitting valve. Aiid so efficiently does it do its job that when it is placed in a permanent position no fewer than fifty of the hitherto “latest” high-power valves will bo put on the permanently retired list while it does their work for them!

Alone, it is capable of operating the main transmitter at Rugby, the world’s biggest radio station. And the really remarkable, thing about this colossus is not its enormous s'zc*> but its extraordinary ingenuity. It is a complete break-away in valve de sign, and all the precedents have gone overboard. /

HANDLING HUGE POWER. As everyone knows who uses a super-power valve, one snag about handling big power in a valve is that the valve gets hot. And the more power you handle the hotter it gets. So ' thjat with transmitting valves which handle huge power, the danger is that the heat will melt the metal, melt the glass, or in other ways impair Ahe immensely high vacuum which is an essential feature of the construction.

For years research workers have, pondered over the problems of maintaining a very high vacuum, handling enormous power, and *at the same time dissipating .the inevitable heat engineered..,, . . . .... It is now standard practice to pump many gfillons of water round the • ahodes Of large transmitting valves, to k£ep them cool while working, and at least one station in Europe, Warsaw 'on 1411 metres) employs a water-cooled filament as well. But one great snag was always present with these complicated valves, and that was that the slightest flaw in one of them represented a heavy loss. Ordinary receiving valves are expensive enough, but even a wealthy broadcasting company lias to think carefully about renewing of valves when one valve replacment may mean anything up 'to £SOO. In the last three years in the Research Laboratories of the Metropolitan Vickers Electrical Coy. all valves which gets round all these difficulties has been thought out, and produced. Quite recently, the Americans were acclaiming proudly that they had produced a valve capable of handling 200 kilowatts, but this figure fades into insignificance beside th*e power-handl-ing capability of j Britain’s biggest valve, whch is capable of handling the staggering total of 500 kilowatts 1 The reason that its glass does not melt is that is uses no glass at all in the construction, but is, instead, composed of a compound of steel, porcelain, and copper. Unlike the old valves—the electrodes of which worked in a vacuum that was sealed up during the manufacture and therefore could not be tampered with—this latest monster is kept absolutely empty all the time it is in operation. And the result is that it can be dismantled.

If something goes wrong with its water-cooled steel anode (which, incidently, weighs, about three cwt.), the valve is not. ruined. The pumps can be stopped,,-the whole thing can be taken adrift and eventually the anode can be brought out into the open and there hit with a hammer if necessary.

AMAZING FACTS. When tile repairs are finished, it can rapidly be put together again, the whole valve reassembled, and placed back in operation in the course of a few hours. The vacuum, in fact, need not now be considered a permanency, but it has become part of maintenance, and as such comes into line with the filament heating, the anode cooling, and ether precisely similar and common maintenance jobs. And here are a couple of amazing facts. Every minute that the valve is in action, no less than 40 gallons of water must circulate round it to keep it cool enough to work. And such is the power handling capability of it that even the grid has to be water-cooled. While the scientists of the world have been congratulating British scientists on this latest marvel, and marvelling at British inventive genius, their minds have been, wondering and wondering whatever the end of it will be. For though designed pri-

marily for wireless communication, this valve looks like revolutionising other fields of electrical .engineering. The engineers, scientists, and ie search workers are now realising t at it could easily have been made much bigger. It appears to open the door of a hitherto unexplored domain, of enormous possibilities. But that is all in the future. In the meantime, there it is—Britain’s giant valve.