Monthly Archives: April 2018

1948 Printed Circuits

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Seventy years ago this month, the April 1948 issue of Popular Mechanics introduced a new term to the electronics lexicon, namely the “printed circuit.”

The magazine noted that this truly “wireless” technology was made possible by research by the Bureau of Standards during World War II.  The worker shown above, at Spraywire Laboratories, Inc., of Minneapolis, is making a  board.  It explains that a circuit stencil is applied to a material such as plastic or ceramic, after which a sandblasting process was used to form grooves.  Finally, the grooves were filled with molten metal to form the conductors.

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1938 One Tube Shortwave Regen

Screen Shot 2018-04-27 at 11.30.06 AMWhile Fido keeps a watchful eye, the father-son team here is putting together the one tube regenerative shortwave set shown 80 years ago this month in the April 1938 issue of Popular Mechanics.

Screen Shot 2018-04-27 at 11.35.06 AMThe set ran on three flashlight batteries. Two of them in series provided the 3 volts of B+ necessary to run the type 49 tube, with another powering the filament.

With four plug-in coils, the set covered 18 to 200 meters. A good antenna and ground were required, as were high-impedance headphones. But as evidenced by the QSL cards shown in the illustration above, the simple circuit was capable of pulling in DX.

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1959 Young Soviet Radio Enthusiasts

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These young comrades were pictured on the cover of Семья и школа (Family and School) magazine, April 1959. Unfortunately, I can’t find any article inside the magazine that goes with the cover. Perhaps one of our Russian readers can fill us in!

But these gentlemen, now about 70 years old, seem to be having a good time pulling voices out of the aether.



WNAX Yankton, 1943

1943Apr26BCSeventy-five years ago today, the April 26, 1943 issue of Broadcasting carried this ad for South Dakota blowtorch WNAX in Yankton. As the ad noted, the the station’s tower stood 927 feet, then the highest in the country.

Due to the area’s good ground conductivity and the station’s low spot on the dial, the station still has the second largest daytime coverage area in the nation, putting a respectable daytime signal into Minneapolis/St. Paul, Fargo, Kansas City, Omaha, and Des Moines.  The station’s current tower stands 911 feet, and is also accompanied by two other towers used for the station’s nighttime pattern.

The station’s transmitter building shown here still stands.  The studio in Yankton was destroyed by fire in 1983 and rebuilt outside of town.



1948 Australian “Crystal King”

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Seventy years ago this month, the April 1948 issue of the Australian magazine Radio and Hobbies showed how to make this simple crystal set, dubbed the “Crystal King.”

The author noted that the magazine’s readership including a lot of “young chaps who are just beginning to discover what radio is all about,” and that he remembered the first radio he ever built, and that the questions and problems he came up against, while silly in retrospect, seemed very important at the time. Accordingly, the article goes into sometimes excruciating detail as to such minutiae as what kind of wire to buy.

The set was neatly built on a wooden basebaord with a shellacked front panel. It was said to be able to pull in stations within about 10-15 miles. Occasionally, more distant signals could be heard, but “everything must be on your side if such reception is to be certain.”

The main advantage of the crystal set was that it needed no battery and thus no operating costs. However, “if you are a young lad who has built this set just for experiment and your Dad already has a license for a set you won’t need to pay for another one. Only if you intend to keep it built up as a permanent installation is another license required for it.”

I wonder how many young Australians built the set as a permanent installation, which presumably required a license.

The circuit is quite basic, with the coil tapped on both the antenna and detector side, with a vairable condenser for tuning. The crystal is mounted on the front panel, and the article notes that other types of crystal holders can be employed.

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American Leader Midget Pocket Radio, 1938

1938Apr23RadioGuideEighty years ago today, the April 23, 1938, issue of Radio Guide carried this ad for a midget pocket radio from American Leader, 1606 W. 78th Street, Chicago.  Since it needs “no batteries, tubes, or electrical connection,” it appears to be a crystal set.  The ad promised that you can use it anywhere–“in auto, bed, office, hotel, etc.” and that it’s not a toy.  The set sold for $2.99, and the seller covered the postage on cash orders, or you paid a few cents if sent C.O.D.

I suspect that the antenna and ground connections would get a bit tricky in a car,   But subsequent research reveals that it was a quite attractive little crystal set.  The image below appears at Wikimedia Commons:

The caption of that photo reveals that the headphone is stored in a compartment inside the set.  So as long as you had an antenna and ground connection nearby, the set probably was something more than just a toy.



Making Movies in a Volcano, 1933

Screen Shot 2018-04-20 at 11.14.30 AMEighty-five years ago, the cover of the April 1933 issue of Popular Science shows cameraman Arpad Kirner being lowered by a fireproof rope 800 feet into the mouth of an active volcano in Italy. He explained that while his colleagues contented themselves on looking down into the volcano, he was able to view phenomena unseen by any human before.

Accompanied by friends (selected for strength to work the winches), he went down and studied the walls with an electric light powered by a wire running alongside the rope.

Of course, it is quite apparent that this stunt was dangerous and should never be repeated. This, of course, is because both the rope and parts of Kirner’s suit were made of deadly asbestos.

Despite the danger posed by the asbestos, Kirner was lucky and lived to the ripe old age of 78, as documented by his grave in Slovakia.



1918 Train Dispatching

1918AprElectricalExpA century ago, with much of the labor force off to war, American industry turned to women to fill many jobs traditionally held by their male counterparts. Shown here is one of the hundreds of young women being trained to be train dispatchers. The article, in the April 1918 issue of Electrical Experimenter, pointed out that the job was exacting, and in the real world, mistakes could easily mean death or dismemberment. Therefore, the women were trained on the model railroad shown here, before being unleashed on the real rails. The dispatcher would set signals and switches, with the model trains responding.



SPARS Radioman

1943AprRadioServiceDealerCover1943AprRadioServiceDealerShown here on the cover of the April 1943 issue of Radio Service Dealer is a SPARS Radioman, a member of the female branch of the Coast Guard. The magazine noted that women were relieving trained radiomen for combat duty, and in the process earning ratings and regular Coast Guard pay and training.

A recruiting ad in the same issue encourages women ages 20-36 to “get into a trim uniform” and put the country one step closer to victory. Those with two years college work and experience were eligible to apply at once for an officer’s commission.

 



Philips Adagio 52

PhilipsAdagio52This avid shortwave listener is pulling in a program on her Philips Adagio 52, model BA-511A.  The six-tube Austrian set from 1951 covered longwave, medium wave, and two shortwave bands.  One of the bands covered 15-51 meters.  The second band featured a bandspread to separate stations on the crowded 31 meter band.