This young man is pulling in the proverbial strong local station thanks to one of two sets described in Popular Mechanics 70 years ago this month, June 1951. Both sets are billed as low-cost sets for young radio experimenters, and the magazine noted that such designs re not as plentiful as they should be.

The set above is a crystal set using a galena detector. The tuning coil is wound on a rectangular piece of wood under the chassis, and there is an opening on top for a slider.

The father-son team at left have upgraded the set. First of all, instead of a galena detector, this set uses a 1N34 diode. And for added volume, it employs a 3Q5-GT tube as audio amplifier. For the B+, the set uses 9 volts, but the article points out that for added volume, as much as 90 volts can be used.

If you are thinking of recreating one of these designs, you might find ideas for sourcing parts at my crystal set parts page.

Eighty years ago this month, as shown in the June 1941 issue of Popular Mechanics, Junior was so pleased with his new crystal set that Dad decided to make a second one for himself. The set was so small that it was built right in to an old set of “Baldwin” style headphones, which had an extra large Bakelite shell and cap to house the set.

Into the bottom of the shell was placed a spiderweb coil, and the the shaft of a small tuning condenser was mounted in a hole drilled in the bottom. A wire with a spring clip was used for the optional but recommended ground connection, with another for any convenient antenna.

Eighty years ago, the hapless radio serviceman at left was making his customer wait for a relatively simply job to be completed. The one at the right, however, was able to proceed immediately with the job, thanks to having in stock a kit consisting of 18 volume controls, along with various switches and shafts. He didn’t have to wait for the exact replacement. He just located the resistor of the correct value, and then added the shaft himself, tapping it in place with a hammer. If a switch was part of the control, it was an easy matter to add that as well.

The set of 18 controls sold to the dealer for $14.97, with a total list price of $29.95. The kit came from the International Resistance Company of 401 N. Broad Street, Philadelphia, and this ad appeared in the June 1941 issue of Radio Retailing.

Eighty years ago this month, the May 1941 issue of Radio Service Dealer carried this ad showing the 1941 lineup of radios from DeWald Radio, 170-16 Jamaica Avenue, Jamaica, New York.

The ad features the model 562, an All-American Five with a suggested retail price of $19.95, as well as a portable at the same price point, the model 410.

The model 565, retailing for $24.95, was a portable that also ran off household current.  Finally, the model 670 had a retail price of $33.50 and was a six-tube set tuning the broadcast band as well as two shortwave bands, 4.7-10MHz and 11.5-24MHz.

Seventy years ago, these picnickers were enjoying a favorite radio program while on their outing, thanks to their portable radio. But they would have never thought of it if it weren’t for the foresight of their radio dealer in suggesting one.

The picture appeared in the May 1951 issue of Radio & Television Retailing magazine, which pointed out that most people were not “portable conscious.” The dealer needed to help them out through advertising in the store, especially in connection with summer gift-giving occasions such as graduations and weddings. And while the magazine was gearing up for the summer season, it reminded readers that the fall hunting season or Christmas were just around the corner, and it was a good idea to plant the seed.

The magazine suggested exchange advertising. For example, an excursion boat line might be interested in placing a poster with rates in the dealer’s shop, in exchange for an ad for the radio shop at the ticket office.

This hundred-year-old circuit, from the March 1921 issue of Radio News, initially had me a little mystified, since the accompanying article describes the set as a “C.W. transmitter.” But I searched in vain for the rectifiers in the power supply and found none.

The mystery was solved by loyal reader NM0S who pointed out that it’s not exactly a CW transmitter–it’s actually a modulated CW (MCW) transmitter, which puts out a 120 Hz tone. He points out that this is the same type transmitter employed by Art Collins, 9CXX (later W9CXX and then W0CXX), to make contact with an Arctic expedition in 1925. There’s no rectifier because the tubes plates are hooked directly to the AC. As you can see, one tube is hooked to each end of the transformer winding, meaning that each one of them will be “on” for alternating halves of a cycle. As a result, the output will be modulated with a 120 Hz tone, meaning it can be copied with any receiver, even a crystal set.

The manufacturer of the set is not stated, only that it is an “eastern radio corporation” that had recently entered the market, and had been on display at a recent radio convention at the Hotel Pennsylvania in New York.

The set was designed for operation with two type U.V. 202 tubes, and even though the tubes were rated at five watts each, the set could be run at an overload of 100 percent, for an output of up to 20 watts, at the cost of reduced life of the tubes. The magazine noted that the set would be suitable for places such as summer camps. It reported one notable QSO during the daytime between 1DH in Boston and 1DAC in York Harbor, Maine. This was accomplished with an antenna of only 27 feet, one foot above the roof.

Shown here is a one-tube transmitter for 80 or 40 meters from the May 1951 issue of Radio News.

The 12-watt set’s main feature was its compact size. The author, Leon Wortman, W2LJU, noted that he knew at least one ham who had stayed off the air “because of the apartment shortage.” Whenever that ham expressed a desire to get back on the air from his cramped apartment, he wife protested that there was no room for equipment, nor even room to hang her nylons. The transmitter itself measured only 3 by 5 inches, although it also called for a similarly compact power supply which could be tucked away. The transmitter itself was crystal controlled using a 6V6GT.

Voltage doubler. Wikipedia image.

The power supply employed a 117 volt isolation transformer, but used a voltage doubler circuit to supply the B+. The author noted that the circuit was by no means new, and was employed in many receivers. However, it was rarely used in ham gear, and it was intriguing to think that you could take a voltage and double it without the use of inductors or transformers. It does this by charging a capacitor on each half of the cycle, and then placing those in series. In this case, the unit employed selenium rectifiers.