Radio of Yesterday and To-day

Radio Record, Volume III, Issue 24, 27 December 1929, Page 3

Radio of Yesterday and To-day

Comparison and Contrast at Chicago Radio Exhibition Contrast and comparison are always interesting, and it is not surprising that when the main feature of the Chicago Radio Exhibition was a display of antiquated apparatus alongside ,the ultra-modern, that this was one of the most successful shows yet held in America. This unique display included relics of great value-original Fleming valves,.a Marconi kite aerial which was used in the triumph of that inventor’s life-the bridging of the Atlantic; the first telephony apparatus to span the "pond," and a model of the first neutrodyne. But this. was not all, the newest all-electric circuits, remote and automatic controls, a device for visual tuning, and a totally new instrument, were in contrast.. The accompanying article, from the viewpoiat of a ore than casual" observer, tells in detail the story of this remarkable show.

O the average visitor, the 1929 ™ Radio Show was probably ! | "just another show." But to ¢ the thoroughly inoculated radio enthusiast, veteran of many shows, there is just a little more than period furniture and suave demonstrators.. ‘° , The veteran radio show-goer is on an errand, and: goes almost directly to his objective, and moves on. He is looking for things that the blind enthusiast ca¥not, see. He probes into chagsis, does behind the scenes of period cabinets and directs his inquisitive gaze into the "innards" of all apparatus. . This year he investigated the screen grid. radio receivers. He knew, of course, that screen grid valves were listed as one of the show’s "sensations." ' What he wanted to see, however, was:

he way in which these valves were ‘sed. in radio circuits. So he looked for genuine bandpass filter circuits and to his astonishment discovered that ’ only three, possibly four, manufactur. ers. had worked. it into their new ~ models. He saw that there were several varieties of the same idea, and that there can be bandpass filters, and tun. ed filter bandpassers. While looking for the new screen grid bandpass circuits, he discovered a receiving set that only used a single stage of audio amplification in pushpull, ‘immediately after the detector, preceded by four stages of screen-grid amplification.. This, according to quick figuring, should give amplification into the millions! He saw for himself \. power detection (anode bend) automatic volume control, installed both in ‘yadio and audio circuits, but because of the complexity of wiring, and the genera] unwillingness of engineers to divulge their "secrets," he went away comparatively wninformed on the "how" of. the'meéthod.; « '

HERE were other things that engaged his attention, which as an old-timer in. the matter of show. inspection and radio history, he: was equipped to thoroughly appreciate... In a corner, for instance, and quite unobtrusively presented to the gaze of the onlookers that ignoringly glanced at it, he discovered the model of the original "neutrodyne" circuit receiver,. as built by Professor Louis A. Hazeltine, the inventor. He. recalled his own home-made neutrodyne set of many years ago, and observed that there were still many neutrodynes at the present show, though in modified or improved form. Another sight which interested him as an old-timer was the early mode! TRECTRRRERERERTE RRR REM ERE EERE SERRE ERE EEE eee eeceeeae

veteran show-goer saw replicas of Mareoni’s first trans-Atlantic receiving receiver built by the’ amateur pioneer Alfred H. Grebe. In the "pile" of sets he saw also an amateur transmitter for short-wave work, one of the first commercial sets, and, he learned, the very one that an amateur used to speak directly with Europe for the first time. This was probably ten years ago! Compared to these relics, the crystal set that won the "radio relics" contest was a grown-up boy!

T seemed that there were several other "historical" displays that are really part of radio history. | For. instance, he lingered long enough before the cases showing Dr. De Forest’s’ Bunsen burner detector, which the good doctor himself says was the original step in the invention of the world-famous audion, which is shown in its original state alongside of the burner. A little farther along, the set, including one of the real kites used to support the antenna. Then, there was an "SOS" ("0.Q.D.") key, | the same, indeed, which had sounded the s.s. Republic’s call of distress. Here was a relic indeed! Next, after finding that the minia

ture models of radio installations: on ships were working mo-els, and that the small direction compass could actually turn and has,a needle in its base, the show-goer turned his attention to the newer ‘devices of radio science. For a*long time he had wanted to see the recording machinery used for making talking pictures. Here, was one of the instruments, bare of any covers, and easy enough to look over in great: detail, since hardly anyone

took notice of it! Aside from an automatie voltage regulator, which the show-goer had heard of before, and which semeed to actually work, though built on a transformer principle and labelled as somethng "really different and new," there were other novelties that engaged his attention. HERE were remote and automatic controls for tuning in radio receivers that could be called new. The Motomatic remote control’ was. worth a second look. Bdison’s device for visual tuning interested him, as did the remote tuning arrangement ‘which permitted the tuning, at any distant point, of a receiver located any distance away. The idea used was probably not "new," as it consisted of a remotely controlled motor. The method of control was, however, although it PITITTITITT TTT rita ia tet |

did look a bit complex right there at the booth. There was also an automatie printer for typewriting news on a machine, as pickéd up by a broadeast set. It was fascinating for our show-goer to watch the precision with which these devices tuned in automatically the stations selected. RICK furniture, notably modernistie conceptions as applied to radio, relieved the monotony of too much woodwork, apparent everywhere. It wasn’t until the showgoer could squeeze his way through a group looking under the top of a beautiful table in one particular booth that he discovered that it was a radio receiver built under/it! An automobile receiver, for installation under the cowl, was another interesting development. As becomes an onlooker who has seen enough, our veteran showgoer only casually looked at the television demonstration, to notice that it had visibly improved over last year’s. transmissions. He hard the automatic wireless transmitter and receiver, set up to

show how this was done, on a large Scale, between countries. ‘With all the new electrically operated devices threatening to spoil radio reception, manufacturers of filtering devices have been alert; so that there are few forms of interference that will not yield te one or another of these filters. F particular interest to dwellers in city districts where the lighting service is direct current, is a new product of a well-known manufacturing firm. So new is this, in fact, that as yet neither details or price can be obtained. It will prove an undoubted boon, however, as it is nothing less than & properly filtered and shielded miniature motor generator set; permitting the d.c. dweller to avail himself of the most modern of a.c, receivers. Last but not least-perhaps to show the versatility of radio-was a device known as the Theramin, a totally new musical instrument for the home. An offshoot of radio, the demonstrations of this instrument at the show proved it to be capable of producing. somé really fine tone shadings, both volume and pitch being controlled entirely by proximity of the operator’s hands. PERHAPS the most important thing of all at the Radio Show (speaking now particularly of the Radio World’s Fair at Madison Square Garden, New York) escaped the casual visitor entirely. Seven years ago when broadcasting took the public by storm, the first attempt at a public showing of radio apparatus on the Hotel Pennsylvania roof in New York was swamped, and from the attendance figures at the various shows throughout the country it may be seen that radio interest is far from being on the wane.