I’m not quite sure what the function of this Soviet electronic project was. It appeared in the magazine Моделист конструктор (Model Designer) issue number 7 of 1968, with the cryptic title “In the air – the coach.” The magazine covers model building, so at first I assumed that it was a radio control transmitter and receiver. But the transmitter appears to be connected to a microphone, and the receiver is connected to an earphone. So it appears to be intended for voice communication, and it appears to be for the 10 meter amateur band. The text mentions “300 – 500 meters,” so I assume that’s the intended range of the set. Elsewhere in the magazine is a discussion of “what is the procedure for registration and operation of amateur receiving and transmitting radio stations.”

In any event, the illustrations speak for themselves, and presumably some young comrades put together this QRP 10 meter AM station. Here’s the schematic and pictorial diagrams of the transmitter:

And here are the schematic and pictorial diagrams of the receiver:

This photo from the October 1968 issue of Radio Electronics shows KIRO Seattle disc jockey Jim French taking a traffic report via CB radio. The article noted that instead of depending on helicopter reports, the station had a network of 40 CB-equipped motorists sending in live reports. The studio and CB antenna were located atop the 600 foot Space Needle. The location ensured a coverage radius of 20 miles, but the QRM was described as unbelievable at times.

Ninety years ago this month, the October 1928 issue of Popular Science tackled the vexing question of whether you should buy or build your radio receiver. The magazine noted that as between building and buying, the magazine championed neither option. It viewed its function as assisting with a wise purchase for those who so desired, or to help solve home construction problems for those who decided to build.

The gentleman shown in the illustration opted to build, and the magazine noted that if you enjoyed working with tools, then assembling your own set would yield good results.

It noted, however, that building a radio was really a misnomer. It was really a matter of assembling factory-built parts.

Either way, the magazine stressed that it was important to identify your needs. Was bringing in distant stations the main appeal, or did you put tone quality first?  By first answering these kinds of questions, the radio consumer would wind up with a suitable set, whether they decided to buy or build.

If you look closely at this picture from the October 1943 issue of Popular Mechanics, you’ll see a 1H5 tube lying on the table. This means that the trio shown here decided to build the one-tube version of the receiver described in the issue. Included were the plans for two almost identical receivers, the difference being that the one shown at left used a crystal detector, while this group decided to tackle the only slightly more complicated,tube version, shown below.

For either set, as long as the builder had a good set of headphones, a quick look at the junk box, or a trip to the dime store, would produce the necessary parts.

Either set was mounted on a 10 x 13-1/2 inch breadboard, with the coil wound on a toilet paper tube. The coils were tapped and hooked to the switch that gave the sets, the Toothbrush Twins, their name. The switch was made with the handle of a toothbrush from which the bristles were removed with a pair of pliers. This was used as the slider, which contacted thumb tacks layed out on the board with the help of a compass.

If a shorter antenna was used, this was fed to the coil. A longer antenna had its own Fahnestock clip, and bypassed the coil.  Either set was said to provide excellent results with local stations, with the tube version showing a bit more selectivity.

The October 1943 issue of Radio Craft carried this schematic for a one-tube AC-DC shortwave receiver. The circuit had been sent in by Leo Silber of Springfield, Mass., who reported that in 25 nights, he had pulled in over 200 stations from as far away as Little America, Antarctica.

The set used a 6C8G, with half the tube serving as rectifier and the other half as regenerative detector. Plug-in coils were used along with a variable capacitor for tuning. Silber reported that the set could drive either headphones or a small speaker.

For those wishing to duplicate the circuit, it appears that a 6SC7 can be substituted.  Those tubes are still rolling off the Russian assembly lines of Sovtek, and are available on Amazon.  For information on winding the plug-in coils, see our plug-in coils page, and for sourcing other parts, you can get ideas at our crystal set parts page.

If the circuit looks familiar, it’s because the magazine’s March 1943 issue had carried a slight variation on the same circuit, also sent in by Mr. Silber.  Silber, then a high school senior, was apparently not licensed before the War, but the 1949 call book shows him as holding W1NRP.  He went on to receive his Ph.D. in Physics from Purdue University, and later served as Professor of Electrophysics at the Polytechnic Institute of New York, Brooklyn.  A 1981 biography is available at this link.