Category Archives: Radio history

1938 Distance Learning

The students shown here are now almost 100 years old, but 85 years ago, they were learning about the atmosphere in science class. These students, Marian Oakley, Henry Kehrer, Hannah Esterman, and Bruce Kunkel, were receiving instruction in person from science specialist Harry A. Carpenter, but hundreds of other students were taking part in the same class by radio, on station WHAM.

For several years, the Rochester, NY, schools had been conducting this sort of distance learning via radio. Afternoons, radios would be switched on in classrooms both in and outside of Rochester, and students would get their lectures by radio. Lessons could include well known guest speakers, music programs featuring the Rochester Civic Orchestra, and programs on books presented by the Rochester Public Library. The photo shown here appeared in the February 1938 issue of Rural Radio, and the students shown here attended Frank Fowler Dow School No. 52.

1938 Utah Junior Transmitter Kit

Eighty-five years ago this month, the February 1938 issue of Popular Mechanics featured this 25-watt CW transmitter kit, the Utah Junior transmitter from Utah Radio Products of Chicago. The kit sold for under $16, not including tubes, meter, and crystal. The transmitter used a 6L6, with the RF stage mounted on one chassis and the power supply mounted below it for a neat design. To make assembly foolproof, small components came pre-mounted on the chassis.

You can read more and see a nicely restored example at W0VLZ’s blog.

Burns’ Electric Shop, Lancaster, WI, 1923

If you lived in a small town or out in the country a hundred years ago, you probably heard of radio. And if you were lucky, you probably got a chance to hear one. But it would have seemed risky to buy one. Would you be able to pick anything up, or would it wind up being a waste of money.

Burns’ Electric Shop in Lancaster, Wisconsin, took away the risk, as shown in this ad in the Grant County Herald, February 21, 1923. They would put a set in your house for five days at their expense, and then the radio would sell itself. It probably wasn’t a big risk. The town was in southwest Wisconsin, and eastern Iowa was a hotbed of radio activity at the time. At night, those stations would come in loud and clear, as well as stations in Chicago and more distant places.

1938 Directional Antenna

This gentleman is adjusting his directional antenna, using an interesting design shown in the February 1938 issue of Popular Mechanics.

The antenna itself consists of two doublet antennas at right angles. The combined antenna is fed with a four-conductor feedline, and down in the shack is a switch, allowing for nine different combinations. While this design wouldn’t work with today’s ubiquitous coaxial cable, it probably did help boosting your signal in one direction, or nulling out some interference.

It appears to be a commercial product from TACO, the Technical Appliance Corp. of Philadelphia, which was purchased in 1961 by Jerrold, and then by General Instrument Corporation in 1967.

1948 Metal Detector

The plans for this three-tube metal detector appeared in the British magazine Practical Mechanics 75 years ago this month, February 1948. The general circuit is similar to inexpensive metal detectors sold today, although the modern versions are much smaller as they are transistorized.

According to the author, many coins, rings, and other metallic objects, some of considerable value, were found on the sites of old Roman camps in Dorset.

The general idea of this circuit is quite simple. It consists of an RF oscillator, the coil of which is held near the ground. When that coil comes into the proximity of metallic objects, the change in permeability results in a change of frequency. This type of metal detector can work quite well, but it does require a bit of practice. The detector makes a loud squeal, and the best way to use it is to tune it carefully so that the squeal just barely disappears. If it’s done carefully, the detector can be very sensitive.

Many people have bad experiences with the types of inexpensive metal detectors shown here, some of which look like toys, but that’s because they didn’t take time to carefully adjust them and practice. It’s best to start out indoors, toss some metallic objects on the floor, and then carefully adjust the metal detector and see how it reacts when the coil is brought near the item. After some practice, you can take it outside and look for treasure. The metal detector above, with which Roman coins were found, is actually the equivalent of any of these detectors, and with a bit of practice, one of these will give similar results.

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1943 Emergency Generator

Eighty years ago this month, the February 1943 issue of QST showed this emergency generator. Hams might have been off the air for the duration, but they still had an interest in emergency needs, including WERS operations.

It was powered by a Briggs & Stratton gasoline engine normally rated at 1-3/4 HP, but the accompanying article noted that it was capable of up to 2-1/2 HP maximum as shown here. It was capable of putting out 120 volts thanks to a salvaged Dodge 12-volt generator, rewound, and was capable of putting out over 1400 watts. The field coils needed power, and that was provided by a second six-volt generator also driven by the engine.

The estimated cost of the whole unit was said to be $7.50, although the author admitted that this figure might have been somewhat “under-exaggerated.” The set shown here was the second one constructed, and a third was underway.

One of the gentlemen shown on the cover, although they’re not identified, was apparently Warren Copp, W8ZQ. The article mentioned that he was the father of then-eight-year-old actress Carolyn Lee. We’re not sure exactly why that’s relevant, but like the author of the QST article, we believe that’s the kind of thing our readers would want to know.

Col. Richard G. Rogers, 1943 POW Broadcast

We’ve previously written about the prisoner of war broadcasts of World War 2, and eighty years ago today, the Washington Evening Star of February 16, 1943, carried this report of one such broadcast. Col. Richard G. Rogers was being held prisoner in Formosa, and recorded a message to his family in America. As often happened, listeners in America sent news to his family. There were many such letters sent in these cases, as documented in the book Letters of Compassion, but this is the first case I’ve heard of where one listener sent a phonograph record of the broadcast, undoubtedly recorded on their Recordio.

British Auxiliary Territorial Service, 1943

This young British woman, shown on the cover of the February 1943 issue of Radio Craft is a member of the Auxiliary Territorial Service (ATS), and was tasked with spotting enemy planes. According to the magazine, she and her colleagues shared much of the credit for winning the Battle of Britain.

The young women of the ATS took over important “desk jobs,” freeing men to serve in combat. Their training was intense, and required intelligence and keen perceptive powers. In particular, the work shown here at a radiolocation station required keen senses of sight and hearing, as well as concentration and constant alertness.

One Tube “Saskatchewan Space Charger” Receiver, 1943

Eighty years ago this month, the February 1943 issue of Radio Craft carried this circuit for a simple one-tube regenerative receiver. It had been sent in to the magazine by one Joseph Niwranski of Brooksby, Saskatchewan, and was dubbed the “Saskatchewan Space Charger. The set, which employed a 1A5GT tube, was said to perform splendidly. It reportedly had enough pep to drive a speaker on strong stations.

According to this Find a Grave entry, the author was about 17 when he designed the circuit. He died in 1992 at the age of 67.

1948 Magnetic Recording

The drama student shown above appeared on the cover of the February 1948 issue of Radio News. The young thespian was an early adopter of magnetic recording technology, one of the many civilian technological advances that came from wartime industry. She used a wire recorder from Webster-Chicago Corp. to practice her diction and delivery.

Of course, home sound recording had been possible for some time, thanks to disc records such as the Recordio. But magnetic recording media had the great advantage of being reusable.

The magazine contained a number of features, and it does contain a very complete look at the state of the art in 1948. The two competing formats were wire and tape. Wire held a slight lead in fidelity, but tape was easier to work with, especially when it came to editing and splicing. Interestingly, the magnetic recording tape of the time was actually paper tape with a thin magnetic coating. Typical speed was 8 inches per second.

Among the features of the issue was a construction article for the tape recorder shown here. The project was said to be “well within the capabilities of anyone who has a working knowledge of electronic circuits and who has ordinary mechanical ability.” The mechanical ability was important, because all of the parts had to be made. A metalworking lathe was required, although the article noted that those without one could have the parts custom made at a local shop at low cost. As one of the mechanical diagrams shown at right shows, the construction did require some mechanical skill. Apparently, 75 years ago, that level of skill was ordinary.

The recording/playback and erase heads also had to be homemade, and consisted of a coil wound on a laminated core and placed in a shielded enclosure with just a small opening for the tape. The choice of material for the core was critical, and had to be permalloy. The type of material normally used for transformer cores would not work. The best solution was to buy a particular type of audio transformer, disassemble it, and use the lamination material for winding the heads.

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