Monthly Archives: March 2022

Tree Antenna, 1962

Sixty years ago this month, the March 1962 issue of Electronics Illustrated carried these self-explanatory plans for the stealth antenna shown at left. It was billed as a way to fight TV interference, basically by keeping a low profile and thus not alerting potentially suggestive neighbors to the possibility that their picture was other than perfect.

And for the patient ham, the illustration above demonstrates a method of adding multiband capability.

The article was penned by prolific writer Howard Pyle, W7OE.

12 Volt Power in 6 Volt Car, 1952

Finding the right power supply for a particular piece of equipment has always been an issue, as shown by this Hints and Kinks item from the March 1952 issue of QST. There was a lot of surplus gear on the market, much of which ran on 12 volts. Most vehicles, on the other hand, had 6 volt systems. Kermit Karns, W0MYH, of Kansas City, had a 1948 Chevrolet with a 6 volt power system and submitted his solution for running 12 volt equipment in his car.

He simply added another generator and another battery to the car, essentially giving him two independent 6 volt systems, and one 12 Volt system for his radio gear. An additional 6 volt generator, identical to the one that came with the car, was mounted under the hood, and the second battery was stowed away under the driver’s seat. One of the two regulators in the diagram was for a positive ground vehicle, and the other was for a negative ground system.

In addition to being able to run his radio equipment in the vehicle, the added advantage was that the car now had two electrical systems. Karns noted that one was used primarily for the starter with the other loads attached to the second system.

1962 Clown Radio

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We previously showed you a radio at left that was sure to delight the youngsters of 1939. It featured a creepy face with eyes that lit up in time with the music.

Not to be outdone 23 years later, the publishers of Popular Mechanics published in the March 1962 issue the plans for the same general idea shown here. This time, the face, a clown, was a little bit less creepy, but it still had magic eye tubes in the place of eyeballs, and the eyes flashed in time with the music. The magazine gave two options for the project. If you didn’t have a radio to spare, then you could build the entire radio, which was basically a crystal set using 1N34 diode, with two tubes to provide loudspeaker volume. The magazine noted that this worked satisfactorily in downtown Chicago, and pulled in three different stations with a 50 foot antenna on the roof. According to the magazine, this simple circuit was “the minimum performance which might satisfy youngsters.”

But for better performance, it was recommended to just use an existing radio, and tap in the additional circuit, shown below, to flash the eyes. The magazine showed a template for cutting the clown face, but also noted that the prepunched chassis and clown face were available from the Experimenter’s Supply Co., 1924 W. Columbia Avenue, Chicago.

1922 AM Transmitter

A hundred years ago this month, the March 1922 issue of Popular Mechanics carried the full construction details for this AM transmitter for the radio amateur. Heretofore, constructing such a transmitter was an expensive proposition, since it invariably required a motor-generator to provide the high voltage. This transmitter, however, used a “new type of transformer” to supply the 500 volts of B+ from household current, “as simply as screwing in a lighting bulb or plugging in an electric iron.” Two rectifier tubes could be of “any of the various types on the market,” and the transmitter itself used three UV-202 tubes.

The price of all of the parts was said to be about $125. According to this inflation calculator, that works out to over $2000 in 2022 dollars, so this was not the project for the impecunious.

The article noted that the exact range would, of course, vary with local conditions. But the author reported that music and voice had been transmitted from 100 to 200 miles, and under especially good conditions, an extreme range of 500 miles had been recorded.

The author, whose later call sign was W9DCX, went on to become the magazine’s radio editor. He died in 1955, as noted in his obituary in the magazine.

1947 RCA-Victor 65U Radio-Phono

This ad appeared 75 years ago today in the March 10, 1947, issue of Life Magazine. It’s for RCA Victor’s model 65U radio-phonograph. It’s a typical “All American Five” broadcast radio with automatic record changer. It has a large elliptical speaker, and it’s a nice sounding radio.

I actually own one of these that I got back into working order a few years ago. The automatic record changer (said to be capable of 12 ten-inch records or 10 twelve-inch records) stopped working a long time ago, but the phonograph still plays manually. The original cartridge was no good, but I substituted a more modern ceramic cartridge, held in place with a piece of foam rubber and rubber bands. The lid can be closed completely while records are playing, a relatively uncommon feature of tabletop sets of that age.

1962 Four Transistor “Half Pocket” Portable

Sixty years ago, this listener was probably the first on her block to own a transistor radio. And she was almost certainly the owner of the smallest radio. Smaller than a pocket set, this one was billed as a “half pocket” portable in the March 1962 issue of Radio Electronics.

The four transistor set measured only 1-11/16 x 1-1/2 x 11/16 inches, with a 2N345 serving as regenerative detector, with three 2N207’s amplifying the audio. It was “about the size of a petite ladies’ cigarette lighter,” and smaller than some hearing aids. It was said to pull in local stations with good volume and clarity, and required no external antenna or ground.

1962 Grocery Prices

For a snapshot of grocery prices 60 years ago, this ad appeared in the Arizona Sun on March 8, 1962. There’s been a lot of inflation in that time period, and according to this online inflation calculator, one dollar in 1962 was the equivalent of $9.31 today. So the dozen eggs for 39 cents look like a bargain, but that would be the equivalent of $3.63 in today’s money.

Some items, on the other hand, really were cheaper back then. You could get three pounds of ground beef for 89 cents. That works out to the equivalent of $2.76 per pound.

1947 TV Kit

If you wanted to be the first on your block to have television 75 years ago, and you were reasonably adept with a screwdriver and soldering iron, then this kit might be just the thing you needed. When you were finished, you would have a set with a 7-inch picture tube, large enough to be viewed comfortably by 10 or more people. You could put it into operation at any locality where television reception was available.

The kit retailed for $159.50, and was geared up especially for schools. All difficult assemblies were prewired, so you didn’t have to worry about getting it into alignment. It cam pre-tuned for three channels of your choice, dictated by which stations were on the area in your area.

While no cabinet was included, it is noted that the 3000 volts were carefully protected by insulation, an interlock switch, and a bottom plate under the chassis. This description appeared in the March 1947 issue of Popular Mechanics.

Prewar Radio Allocation Table

For a snapshot of how the radio spectrum was allocated 80 years ago, this chart appeared in the March 1942 issue of Radio Retailing. You can click on the image above for a full-size image, and on most browsers, click again to enlarge.

While America was now in the war, the allocations above are really the last prewar allocations, as they would have appeared on December 6, 1941. Since then, for example, Amateurs had left the air for the duration. At the time, the amateur bands were on 160, 80, 40, 20, 10, 5, and 2-1/2 meters. Postwar, the allocations would be similar on 160 through 10, with the addition of the 15 meter band a few years after the war. The VHF allocations shifted slightly to 50 and 144 MHz.

With some changes, the TV channels were in their postwar configurations. FM broadcasting would move from the 42-50 MHz band up to its present allocation at 88-108 MHz.

Science Fair Idea: “Lens” for Sound

For students looking for a simple but impressive (and slightly dangerous) science fair experiment, this one from the March 1937 issue of Popular Science is almost certain to bring home the blue ribbon. It demonstrates that sound waves can be manipulated with a “lens” in the same way that light can. In this case, the “lens” is made up of a balloon filled with carbon dioxide. Since the CO2 is heavier than air, a bubble full of this gas refracts the sound waves. This can be shown, as hear, by using the “lens” to amplify a distant sound. To prove the effect, another balloon filled with normal air can be compared. If the teacher requires that the project answer a question, then the question can be, “can sound waves be focused in the same way as light waves?”

To generate the carbon dioxide, the method suggested by the magazine is to place some limestone into a bottle containing muriatic acid. The balloon is placed on the bottle and quickly inflates with the carbon dioxide produced by the reaction.

WARNING: Muriatic acid is another name for hydrochloric acid, and it’s very dangerous. You need to take precautions from getting it on your skin, and especially your eyes, since it could blind you. Do this part of the experiment outside, wear eye protection, and follow these other safety precautions. But you can get the muriatic acid at your local hardware store or on Amazon. For children too young to handle the acid, a parent or teacher can produce the carbon dioxide and give the balloon to the child. The balloon full of CO2 is perfectly safe.

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