Eighty years ago this month, the March 1938 issue of Popular Science carried the plans for this transceiver, which it billed as the world’s smallest two-way radio. Weighing less than ten ounces, the set could be carried in a coat pocket. The set shown here was for the 3/4 meter band, but could also be built for the 1-1/2 meter band. The heart of the circuit was a 955 acorn tube.

A DPDT switch was used to switch from transmit to receive. In the transmit position, the circuit was an efficient oscillator, and in receive, a grid leak and condenser were added to the circuit to produce a sensitive receiver.

The external batteries were acually larger than the radio. Two 3-volt flashlight batteries were used for the filaments, with a 45 volt battery providing the B+.

In order to make sure the radio was operating within the amateur band, the article described a simple wave meter, consisting of a flat U-shaped loop of No. 12 wire hooked to a galvanometer. The transmitter was held close to the loop and moved along until the highest current rating was shown. The transmitter wavelength was equal to the distance along the wire to the meter.

The construction article reminded readers that an amateur license was necessary to use the transmitter. But for those considering trying for the license in the near future, the construction of the set would teach many of the radio fundamentals that would be on the test.

The circuit here is similar to this WERS transceiver shown here previously. In case you’re wondering, the 955 tubes do seem to be readily available on eBay.

This one-tube shortwave portable was featured 85 years ago this month in  the February 1933 issue of Short Wave Craft.

The set was awarded honorable mention in a contest sponsored by the magazine, and had been designed for a trip by the author to northern Michigan, where neither AC power nor replacement batteries would be available. Therefore, the main design consideration was low battery drain.  The set was built in the venerable cigar box, which housed all of the parts, including batteries and  antenna.

The author noted that the set could also be used as a shortwave converter with a broadcast receiver by running a wire to the phono input of the radio.  The author reported pulling in W1 and W4 stations at Detroit using only a copper screen in the lid of the radio as an antenna.

Seventy years ago this month, the February 1948 issue of Popular Science showed how to put together this handsome one-tube converter to pull in shortwave signals with a standard broadcast receiver.

The simple circuit, by S.T. Van Esen, W2OXD, was built around a 6BE6 pentagrid converter tube, and tuned 6-16 MHz.  The radio was set to an empty spot on the dial near 1500 kHz, and tuning was accomplished with a tuning dial on the converter.  A second variable capacitor was used to peak the mixer section.

For power, you could tap into the power supply of a transformer set.  Or if the proper voltages were not available, or if an AC-DC set was being used, the schematic for an appropriate power supply was also included.

The article promised the ability to pull in London, Lima, Sydney, Johannesburg, and other sources of news, information, and entertainment that were pouring out of foreign skies.