Seventy-five years ago this month, the March 1945 issue of Radio Craft magazine carried this one-tube receiver, submitted to the magazine by Sgt. L.R. Blattner, who was stationed at Tinker Field, Oklahoma. According to the serviceman, the set gave the maximum performance for the number of components, and it’s hard to dispute that claim. Despite having only one tube, the set had a stage of RF amplification, AVC, and two stages of AF.

The signal is first applied to the pentode section of the dual tube, passed through the RF transformer, and then detected by the plate and cathode of the triode. Then, it’s applied again to the pentode, now acting as an AF amplifier. From there, the signal goes back to the triode where it’s amplified again.

The magazine also carried the shortwave converter below, sent in to the magazine by Richard E. Held of Sioux City, Iowa, who reported that he received stations from Tokyo to Brazzaville.  It tuned 7-11 MHz, and used two tubes that the writer had lying around.

According to Wikipedia, MacGyver was born in either 1951 or 1952, so he couldn’t have been responsible for this wartime power supply. Instead, it was sent in to the the March 1945 issue of Radio Craft by one Richard F. Reed of Jacksonville, Florida. But MacGyver must have been inspired by Reed, since this power supply ingeniously makes use of available parts, despite wartime shortages.

Reed needed to 90 volt power supply, and used this circuit to get it out of a 1.5 volt battery. The transformer could have been an audio output transformer, but Reed had on hand a model plane induction coil, so he used that. In lieu of an inverter, he used a 1.5 volt buzzer in series with the transformer.

For a rectifier, he used the starter from a fluorescent light. He reported that the supply put out 95 volts at 25 mA.

This handsome but utilitarian wartime cigar-box set was put together by G.L. Keirstad of Toronto, and described in the March 1945 issue of Radio Craft magazine. According to the author, the set pulled in all four of the local Toronto stations, as well as WGR and WBEN in Buffalo. At night, it would also get the New York stations with loudspeaker volume quite adequate for a personal radio.

In March 1945, the war was still on, and that meant that there was no production of civilian radio receivers. But the manufacturers knew that there would be a big sales boom as soon as the war was won, and they were getting their name before the public.

This ad from Stromberg-Carlson appeared in Life Magazine 75 years ago today, March 12, 1945.  And the company was betting on the miracle of FM being the wave of the future.  These young people are listening to some postwar program daydreaming.  The girl dreams of marrying the man of her dreams, and her tenderfoot little brother dreams of being the patrol leader of the best patrol in town.

Every year, Popular Mechanics featured plans for a receiver dubbed the “Little Giant,” and these gentlemen are putting together the version described in the magazine’s March 1945 issue.

Despite a war going on, this set was somewhat more elaborate than most.  It featured push-pull audio, with two 6G6-G tubes driving the speaker.  To drop the voltage for the filament string, a 40 watt light bulb was used.  It could be mounted on the chassis, or a lamp could be plugged in to the radio.  The set used a TRF circuit, and the magazine recommended a 75 foot antenna to pull in distant stations.

Yesterday, we featured this brain teaser from the  March 1945 issue of Popular Science.

At first glance, it looks like it will work.  If you trace the path with button a pushed, bell A should ring.  But what you might not have noticed is that with neither button pushed, both bells are hooked up to the transformer in series.  So they will ring continually, albeit probably at reduced volume.

So wartime shortages or not, Jones will have to scrounge up some additional wire.

Wartime shortages were undoubtedly the reason that Jones tried to save wire when hooking up his two doorbells. But can you figure out what went wrong? We’ll have the answer tomorrow.

This item appeared 75 years ago this month in the March 1945 issue of Popular Science.

Seventy-five years ago, this Chicago war worker was testing RF chokes for their Q factor as they rolled off the assembly line of the Ohmite Manufacturing Company plant. The picture is the cover of the February 1945 issue of Radio News.

Seventy-five years ago, this trapezoidal building was the home of Mahr & Van Name, a radio dealer at 29 Beach Street, Stapleton, Staten Island, New York. The shop was featured in the February 1945 issue of Radio Retailing.

According to the magazine, both before and during the war, the shop stressed quality and material, rather than selling on a grand scale. With wartime shortages, that philosophy proved to be especially important.

Even before the war, the shop also sold table lamps, and those sales, along with service, kept the store open during the war. The owner predicted big things for both FM and TV, both of which the store had sold before the war.

As shown from the current Google Street View shot, the building still stands, although its unclear who occupies the radio shop’s former space.