Category Archives: Radio history

1945 MacGyver Power Supply

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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.

 



1945 Three Tube Broadcast Set

1945MarRadioCraftThis 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.

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Stromberg-Carlson 1945

1945Mar12LifeIn 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.



Is Your Portable Ready to Roll?

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On the first warm weekend eighty years ago, this couple were taking their portable radio for a spin around the lake.  It was pulling in the stations thanks to their foresight in bringing it in to the dealer for a free check of the battery and tubes, and a reasonably priced tune-up.

This promotional poster appeared in the March 1940 issue of Radio Retailing.  Presumably, the dealer cut the page out of the magazine and put it in his window or bulletin board.  He then sat back and waited for the portables to start flooding into the store.



1945 “Little Giant” TRF Broadcast Set

1945MarPM31945MarPM1Every 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.

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1920 Boys’ Life DeForest Radio Ad

1920MarBLOne hundred years ago this month, the March 1920 issue of Boys’ Life carried this ad from the Deforest Radio Telephone and Telegraph Company, 1397 Sedgwick Avenue, Bronx, New York.

Interestingly, I’ve noticed that some ads from this era, like this one, don’t make a distinction between a licensed amateur radio operator, who could transmit, and someone who was just operating a radio receiver as an amateur.  The ad invites boys to write in for a catalog of radio equipment to get the news from everywhere by wireless.  It told them that they could “be an Amateur Radio Operator with your own Receiving Station.”  The ad made clear that the company didn’t sell toys, but instead “practical, scientific Radio Apparatus like that used by Government and Commercial Stations.”  One could start out inexpensively and then build up the station.



Answer to Yesterday’s Quiz

1945MarPSYesterday, 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.



1945 Electrical Quiz

1945MarPSWartime 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.



1960 Aerial Platform

1960FebEISixty years ago this month, the February 1960 issue of Electronics Illustrated the “radio powered sky station” shown here.  It was an artist’s conception of the Raytheon Airborne Microwave Platform.  It could be used for either civilian or military purposes, but would establish a platform 65,000 feet in the air.  From there, it could relay radio or television signals, or serve as part of the nation’s missile defense system.

The craft would be stationary above its power source, which consisted of a beam of microwave energy.  This was picked up by an antenna on the bottom.  It was rectified, and the resulting energy was used to power the propeller as well as the electronic payload.

I’ve never heard of this system being deployed, probably because the bugs never got worked out.  This once classified 1965 military report (authored by Raytheon) speaks in glowing terms of the feasibility of the project (which presumably needed just a few more million dollars).  However, as of 1965, successful experiments consisted of the successful use for ten continuous hours at 50 feet, a far cry from the 65,000 feet planned.  And to keep the craft over the microwave beam, a tether was employed, which would probably be impractical at 65,000 feet.

It seems like an ambitious project for 1960, but it’s probably quite possible today.  It seems to me that battery and solar technology will soon be at a point (if they’re not there already) where it’s possible to have a craft that will stay aloft indefinitely.  And unlike the 1960 vision, it wouldn’t need to stay above a fixed point.  If a craft can stay aloft indefinitely, this means that it can fly anywhere in the world.

It also seems to me that an autonomous military vehicle could derive its power from the enemy’s power grid.  When it needed a charge, it could roost on a convenient power line.  In fact, it could probably get its power inductively from an AC power line merely by flying close.



1940 One Tube Kit

1940LafayetteEighty years ago, the young man (or woman) with an interest in radio couldn’t go wrong with this one-tube kit from the 1940 Lafayette catalog. The set was a “baby in size but a giant in performance,” and pulled in the stations with a single type 30 tube. The kit went for $3.95, but also required the tube for 33 cents, an A battery for 33 cents, and a 22.5 volt B battery for 74 cents.

Headphones were also required, which would set the builder back at least another 66 cents. The set came with a plug-in coil covering the broadcast band, but the young radio buff would almost certainly want to start pulling in the short waves. This was accomplished by ordering a set of four coils for only 74 cents.

The catalog noted that this was the type of set that most hams started with.