Eighty years ago this month, the May 1945 issue of Radio News showed this transmitter-receiver mounted in an “innocent-looking traveler’s suitcase,” and seized from a German spy by agents of the FCC Radio Intelligence Division. It was said to be substantially built and of an up-to-date circuit design. It included a tool set, vibrator power supply, and wire for erecting antennas.
You can see what appears to be the same model at the Imperial War Museum.
Eighty-five years ago, this father-daughter team is hooking up a temporary indoor antenna. But to avoid marring walls or woodwork, they’re following a hint shown in the May 1940 issue of Popular Mechanics. They are using several small rubber suction cups, which can be easily removed when not required.
One hundred years ago this month, the May 1925 issue of Talking Machine World reminded dealers that there was money to be made in the Big Outdoors, namely by selling portable phonographs to those at camps and summer cottages, those on motor tours of fishing and canoeing, or anywhere that a phonograph would add enjoyment.
Specifically, they were selling the Carryola Master, from the Carryola Company of America, 647 Clinton Street, Milwaukee. It was said to give beautiful tone, and its motor was silent in winding and operation.
This ad appeared 75 years ago this month, in the May 1950 issue of Radio Retailing, for the SILAVOX, manufactured by Skinner & Pelton, Inc., 100 N. LaSalle St., Chicago. The add-on device allowed you to use headphones with your television. For private listening without annoying others in the household, the speaker could be shut off. But for the hard of hearing, you could leave the speaker turned on. Both the headphone and the speaker had independent volume controls.
When I worked for Radio Shack in an earlier lifetime, we sold a similar device, shown here in the 1980 catalog. One day, we received an urgent communication from headquarters in Forth Worth that they were to be immediately removed from the shelves. I never heard the exact details, but I believe that someone had managed to electrocute themselves.
Many TV sets of the day had a hot chassis, meaning that there was a 50/50 chance that the chassis was hooked to the hot side of the AC power connection. In addition, there were extremely high voltages inside the set, and even with the set unplugged, there was a possibility that the capacitors still held a deadly charge. So the prospect of a consumer installing one of these was problematic. And if they did the job wrong (or maybe even if they did it right), there was a chance of high voltage running to the earphone attached to someone’s head. It’s actually surprising that they lasted as long as they did.
Eighty-five years ago this month, the May 1940 issue of Popular Science showed how to put together this four-tube (1A7GT, 1N5GT, 1H5GT, 1C5GT) portable receiver. As shown in these illustrations, it was guaranteed to enhance any activity at home or on vacation. Powered by a 1.5 volt A battery and 90 volt B battery, the superheterodyne design could pull in stations 100 miles away during the day, or 500 miles at night, with only the built-in loop antenna. For greater DX, an outside antenna could be connected.
The magazine provided proof, in the photo at left, that the set weighed in at a mere eleven pounds.
Here’s something I’ve never seen before. Radio News carried lists of new TV stations to come on the air, and periodically had complete lists. This one is from the May 1955 issue.
Among the data presented is the wavelength (of the video carrier), but it’s given in feet, and not meters! The only reason I can think of for this is for antenna construction. If you needed to build an antenna of a half wavelength, then you would probably be measuring in feet, and I guess it would save a little bit of time to have the conversion done for you.
But almost anyone building an antenna would know that if you started with frequency, then the formula for the length of a dipole was 468/f. And that formula took into account end effects, and was really 95% of the true wavelength. Has anyone else ever seen radio wavelength expressed in feet?
The plans for this handsome one-tube receiver appeared a hundred years ago this month in the May 1925 issue of Popular Science. The set was said to be ideal for the beginner, but still boasted long-distance reception. Regeneration was controlled by a variable capacitor, and this was said to reduce squealing, by virtue of the fact that only RF, and not audio, was fed back. The set called for an antenna of 75-100 feet. In testing, the set pulled in Chicago from a less than ideal location in New York.
For a look back at 1977 grocery prices, this ad appeared in the Pittsburgh Post Gazette on May 18, 1977. While the prices might look low, there has been a lot of inflation since 1977. According to this online calculator, one dollar in 1977 works out to $5.28 in 2025 dollars.
Still, it looks like there were some bargains here. An 8 ounce tube of Pillsbury biscuit dough was only a dime, which works out to 53 cents today. Ground beef was 69 cents a pound, or about $4.40 in today’s money. And 64 ounces of Coke (what would sell as 2 liters today) is 69 cents, also about $4.40. If you want to see the modern prices, click on the links above to see the same product at Amazon.
What would you have for dinner in 1977?
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Back in the day, kids were warned about things like not listening to the radio in the bathtub, or the importance of wearing shoes in the basement. This was because caution was warranted around many electrical devices, especially the “AC-DC” radio, which was the most common design.
These circuits were such that one side of the electrical cord was often connected directly to the chassis. For some semblance of safety, there were some precautions taken. First of all, the cabinet was often made of wood or plastic, which insulated the chassis inside. Even then, though, there was often a screw visible in the back. In some cases, the connection to the chassis was through a capacitor, although that could eventually become leaky. So taking your five-tube radio into the bathroom probably wasn’t a good idea.
This hint for adding a bit more safety appeared in Radio-Electronics 75 years ago, May 1950. If the plug is plugged in with the correct polarity, then the risk of shock is minimized considerably. These days, if you’re restoring an old radio, it’s a good idea to add a polarized cord and/or a three-prong plug. Even so, it’s probably best not to use it in the bathroom or near the kitchen sink.
Sixty-five years ago this month, the May 1960 issue of Radio Electronics showed that a portable AM radio can made a surprisingly good direction finder. The loop antenna is typically directional, and has sharp nulls as it is pointing directly at the station. You can use this effect to determine your location quite accurately by taking readings from two stations, and plotting them on a map from the station’s known location. The lines should intersect at your exact location.
I have done this before, and by using local AM stations, I can plot my exact location within a few hundred yards. At night, by using distant stations, I can determine my location within a few tens of miles.
Since the radio’s antenna is typically parallel with the case, you can do a good job of plotting by simply laying the radio on the map, and using it as a straight edge. But the article shows a more refined method. You can use an HO-scale model railroad turntable and mount the radio on that. This provides a handy crank, and you can calibrate the dial with exact directions.
A further refinement was to obtain a surplus pelorus and mount the radio in that. This would allow very exact visual bearings to the station. Unfortunately, there don’t seem to be many surplus peloruses (yes, that’s the correct plural) in circulation these days.
Once you know your position, you can navigate directly toward one of the stations by placing your radio parallel with your boat, and simply keep the signal nulled.
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