The plans for this unusual looking two-tube receiver appeared in Popular Science 80 years ago this month, May 1941. The controls were mounted on top of the chassis, meaning that the added expense of a front panel was unnecessary.

The set is billed as having two detectors. In reality, a 1N5G tube is used for the detector, with regeneration provide by a 1G4G following it, with that tube’s output being fed back through a tickler coil to the first stage. This made the set very efficient, to the point where it would be able to operate a speaker directly at some locations. The detector could also serve as an audio amplifier, allowing a crystal phonograph pickup to be hooked in as shown in the schematic below. With the appropriate plug-in coil, the set could be used for shortwave.

A hundred years ago today, May 1, 1921, navigation in New York Harbor became a safer proposition thanks to being equipped with a system of radio warning signals aiding navigation. Lighthouses and light ships had long been present, but they were of very limited usefulness in foggy conditions. Therefore, the lighthouse at Sea Girt, NJ, as well as the light ships Ambrose and Fire Island were equipped with powerful radio beacons.

Official notices had been made to mariners, and many vessels were already equipped with radio compasses in the form of a rotatable loop attached to the receiver. The beacon would identify in Morse, and the bearing could be fixed to within one degree.

Radio had been in operation on the Fire Island for some time, as we recounted previously. That ship was equipped with both a wireless transmitter and a bell. By measuring the time between reception of the radio signal and the bell, distance could be accurately measured.  The Sea Girt lighthouse, however, was the first land-based radio fog beacon in the U.S.

This description of the system appeared in the New York Tribune, May 8, 1921.

Eighty years ago, if you needed room filling volume from your Harmonica, there was no need for additional lung power. Instead, you could move up to the next level with electronic amplification, courtesy of this microphone shown in the April 1941 issue of Popular Mechanics. As shown here, your kids will be delighted at the prospect of this musical entertainment.

The microphone was designed to plug into the phono jack of a radio, and up to five could be wired in parallel for your next harmonica quintet performance.  The microphone was also suitable for guitar, violin, piano, and many wind instruments.  It was manufactured by the Amperite Company, then of 561 Broadway, New York.

Eighty years ago, the radio repairman was a heroic figure, as shown by this illustration on the cover of the April-May 1941 issue of National Radio News.  While the lady of the house and faithful canine companion look on, he is getting this set back into operating condition.

Perhaps he had to replace a tube, or perhaps he was resetting the set’s pushbuttons.  This was necessary since the FCC had just changed the frequencies of most U.S. radio stations on March 29, 1941.  An article in the magazine included a timely feature going into detail on the circuits involved.

A hundred years ago this month, the April 1921 issue of Radio News showed how to build this simple receiver, said to have a cost of only 25 cents. Tuning was accomplished with a variable capacitor consisting of aluminum plates separated by waxed paper. By compressing the plates, the capacitance was changed.

The magazine lamented that there were probably thousands of lads who looked wistfully at the catalogs, only to be discouraged by the high prices. The thought was that if they got a chance to listen in with this inexpensive set, they would be sold on the idea of radio and would soon figure out a way to put together a more impressive station.

Accroding to the magazine, almost every town had a good amateur station holding court on 200 meters, and receiving them even with this simple crystal set would be a simple matter.

I have no doubt that the parts shown here could be had for a quarter. The problem, however, is that the prospective radio ham would still need a headphone with which to connect the set. Looking through the magazine, the least expensive was $4.50, or about $66 in today’s money, according to this inflation calculator.

Those headphones, of course, would still be good when the listener was bit by the radio bug and upgraded to a better set. But the cost of entry to the hobby was $4.75, and not the 25 cents promised by the magazine.