Eighty years ago this month, the July 1946 issue of Popular Science carried the plans for this simple one-tube superregenerative receiver for ten meters. Ten meters was one of the first bands allowed by the FCC after the war, and as a result, the magazine noted that hams were busily firing up their ten-meter transmitters and getting on the air. The band was hot at that time, and the magazine promised that you were likely to hear stations 5000 miles away, often more than you would be able to hear stations 500 miles away. With just a handful of parts, the magazine promised that you could be listening the same day.

Eighty years ago, Hallicrafters came out with the venerable S-38 receiver. It was essentially an “All American Five” circuit, but covered three shortwave bands in addition to the broadcast band, up to 32 MHz. And it had six tubes, since one served as a BFO for reception of CW or SSB signals. It was announced in this ad from the June 1946 issue of Radio News, with a retail price of $39.50.

The receiver was a very basic communications receiver, but got the job done for many a beginning shortwave listener.  While not ideal, it was pressed into service by many beginning hams, often paired with a simple homemade transmitter.  Hallicrafters released five more versions of the S-38, dubbed S-38A through S-38E, until 1961.

Sixty years ago, ARRL Technical Editor Doug DeMaw, W1CER (later W1FB) had a transistor radio that resisted all of his attempts to fix an intermittent problem somewhere in the RF or IF sections. Undaunted, he decided to convert the radio into a 2 meter receiver. He stripped out the offending parts of the circuit, and used that portion of the circuit board to install a superregenerative detector for 2 meters. He replaced the tuning capacitor with a smaller one and used the same mount. And the earphone jack was placed into service as the antenna jack.

The circuit here uses an NPN transistor. Depending on the existing circuit, it would be necessary to use a PNP transistor for a positive ground.  The circuit is shown in QST for June, 1966.

Seventy five years ago this month, the June 1951 issue of the British publication Radio Constructor carried this idea for fabricating a switch that would turn a circuit on when the lid was opened. It was originally built for a cocktail cabinet, to turn on the lights when the lid was opened. But the author noted that it could be used for any circuit.

The cost was basically zero, since the author used an old volume control which was going to be thrown away. The volume control itself was not used (in fact, the slider was removed to make it turn more easily). Instead, only the switch was used. A spring held the switch in the off position, but when the lid was raised, the spring stretched and allowed the switch to rotate back to the on position.

This young woman looks overjoyed, and she has good reason to be. She can have a summer full of picnics, complete with radio, without spending a fortune on batteries, since she made the 6-transistor superheterodyne radio shown 70 years ago this month in the June 1956 issue of Popular Mechanics.

The magazine notes that the initial cost of this all transistor set was higher than a comparable tube set, but the cost difference would soon be made up by the lower cost of batteries. This one would run for many hours on two six-volt batteries, whereas the old fashioned set would quickly go through them by the dozen. The set is superheterodyne, so it will pull in stations along with the best.

We recently carried this image from the the March 1956 issue of Popular Electronics, J.P. Henderson making an adjustment to the clocks at CHU, at the Dominion Observatory in Ottawa.

The station has had that call sign since 1938, and has transmitted daily time signals since 1928. Unfortunately, it now joins the things that didn’t quite make it to their 100th anniversary, since the station is slated to shut down on June 22, 2026, according to an announcement by  National Research Council Canada, the operator of the station.

We would like to think that the station will sign off with O Canada, although we suspect that they’ll just unceremoniously pull the plug.

Eighty-five years ago, the June 1941 issue of Popular Mechanics showed how to put together this deluxe 20-watt PA system. Housed in three units which could be transported together, it was ideal for transport to resorts and summer camps. While it had all of the features of a high-end unit, it was easy to assemble to capitalize on the summer sound market.