Category Archives: Radio history

Treasure Trove of Ten One-Tube Radios: 1942

Seventy-five years ago this month, Hugo Gernsback and the other editors of Radio Craft magazine undoubtedly anticipate the popularity of OneTubeRadio.com, since the December 1942 issue was packed with no less than ten different one tube radios!

The first is the simple set being operated by the young man shown above. This set, the “easy one-tuber” was a broadcast set billed as being for any beginner: “Any schoolboy can build this unique one-tube set at a trifling cost. It is an easy little set to make and will bring in plenty of stations on the headphones.”

“Easy One Tuber” schematic.

This set, which used a type 30 triode, was built in the venerable cigar box, and procurement of this chassis could be done at no cost: “Any cigar store will have an empty one to give you–or perhaps your father will hurry up and finish his latest box of cigars, if you tell him that you are about to build something really useful for once!”

The tuning coil was tapped for variable selectivity. The article noted that the lower the clip was placed on the coil, the sharper the tuning would be. But if carried too far, volume would be reduced.

Regernation was adjusted by means of a variable tickler coil mounted inside the tuning coil. It could be rotated to place the set just on the verge of oscillation for maximum sensitivity.

The article recommended an indoor aerial wire of about 40 feet, but noted that stronger signals would be picked up with a longer outdoor aerial.

One-tube shortwave set.

For the slightly more advanced student, the magazine next carried the “beginner’s one-tube short-wave set” shown at the top of this page and at the left, designed by Francis R. Harris, who noted that “broadcast wavelengths and the programs they carry are very interesting, but the real thrill of radio lies in the short wavelengths–the higher frequencies–on which it is possible to pick up programs of all kinds from the very ends of the earth!”

The set was “the simplest and the best breadboard style that we have yet constructed. It is designed for the absolute beginner who is neither radio man nor mechanic, and yet it will equal or better the performance of many more elaborate lay-outs.”

The use of plug-in coils allowed the set to tune 545 to 16 meters (550 kHz to 18 MHz). The only tools required were screwdrivers, diagonal cutters, long-nose pliers, wood tools, and a soldering iron.

The set used a type 33 pentode. While that tube was designed for AF applications, it apparently functioned well as a detector up to the promised 18 MHz.

The article recommended a 50 foot outdoor antenna, fed into the house with a porcelain standoff. “Don’t under any circumstances, use one of those flat contraptions that is supposed to go under the window.”

This set probably looks vaguely familiar to many readers. While the circuit is not identical, the general layout and construction philosophy is very similar to Alfred Powell Morgan‘s one-tube receiver from the Boy’s First Book of Radio and Electronics. Many radio hobbyists got their start after discovering this book in the elementary school library. Morgan’s set is shown at the left, and has an uncanny resemblance to the 1942 model.

If that wasn’t enough for one tube radio fans, the magazine went further and included eight more “famous 1-tube circuits” shown below.

The seven shown on the page above are first the “Ultra-Audion,” “undoubtedly the most publicized circuit in radio,” the genesis of the regenerative circuit, which would tune all way down to 30,000 meters with appropriate coils and one tuning condenser.

The “Ambassador” was “without question the receiver that longest held the spotlight of popular interest.”

The “Interflex” was a design of Hugo Gernsback’s creation, using a crystal detector with one stage of audio amplification, with no need for transformer.

The “Megadyne” was said to be “of special interest to technicians,” and also combined a crystal detector with one stage of audio amplification.

The “Harkness Reflex” put the single tube to work twice, first as detector, and also as audio amplifier.

The “Solodyne” had been imported from Egnland, and was originally billed as “batteryless.” However, it simply combined the A and B batteries.

Finally, shown here on the continuation page is the “Oscillodyne,” a super-regenerative circuit.

In addition to all of these one-tube sets, the issue also contains some two-tube receivers, as well as a few one-tube phono oscillators.

1957 Boys’ Life Telephone Circuit

Sixty years ago, Maurice Peacock, Jr., of Radnor, PA, got $5 for sending these simple circuits to the “Hobby Hows” editor of Boys’ Life, where they were printed in the November 1957 issue.

The circuit shows how to rig up a telephone system to a friend’s house nearby, using an old radio headphone. One earpiece is used at each end, with batteries wired in series. Peacock explains that the wire needs to be insulated, and suggests that old thread spools can be used as insulators. The basic circuit is shown in figure 1. To save on the cost of wire, a good ground can be used as the return, as shown in figure 2.

I suspect the Boy Scouts of 1957 eventually figured it out, but the diagrams shown here wouldn’t work. A minor change needs to be made.

I suspect that, just like the Boy Scouts of 1957, our readers will quickly spot the problem. When you’ve found it, please comment on our Facebook page.

1942 Army Signal Corps Recruiting

This recruiting ad for the U.S. Army Signal Corps appeared in Popular Mechanics 75 years ago this month, November 1942. It noted that this was a radio war, and that the nerve center of the army needed skilled hands. It suggested a number of opportunities to serve.

Physically fit men ages 18 to 45 were eligible for direct enlistment in the Signal Corps Enlisted Reserve. Those with experience as a licensed radio operator, a trained repairman, or active telephone or telegraph worker would qualify for active duty at once with pay of up to $138 per month, plus board, shelter, and uniforms.

Those without direct experience but “skilled with tools” would qualify for training and ordered to active duty after completing the course.

Degreed electrical engineers, as well as junior and seniors in EE programs, would be eligible for commission.

Young men over 16 having an ability with tools would be eligible for immediate training, with pay of not less than $1020 per year. Even those with a minor physical handicap could find a place to serve.

Billy Hallicrafters to the Rescue Again

A few months ago, we reported how young Billy Hallicrafters used his Hallicrafters shortwave receiver to save the lives of some men aboard a sinking ship.

Here, we see young Billy at it again, saving the life of a pilot in distress, as reported in the November 1957 issue of Boys’ Life.

Billy was apparently late for school that day, but I’m sure his tardiness was excused. We enter the story as Billy’s mother reminds him that it’s time to get ready for school. He prepares to shut down his receiver and get to school, but at the last minute, he hears something truly ominous.

He hears a pilot, apparently in communication with air traffic control, since the pilot is acknowledging a message. But the pilot interrupts the acknowledgment to declare a mayday, which apparently only Billy hears. The pilot had “flamed out 10 miles south of Westport” and was bailing out.

Billy interrupts his school preparations and frantically calls the Civil Air Patrol to report the emergency. Within minutes, a CAP helicopter is dispatched, and spots the parachute. One of the crew comments that it’s a good thing that boy was tuned in, since nobody else heard the Mayday.

The crew quickly gets the unconscious pilot out of the tree where he’s dangling and to the hospital. In the next scene, Billy is visiting the hospital where the downed pilot thanks Billy for saving his life.

Hammarlund Super Pro Console, 1937

The Hammarlund Super-Pro series of receivers represent one of the best performing prewar communications receivers. The line was first introduced in 1936, and when war came, they took the BC-779 nameplate for the military version.

Thousands of the models making up the series rolled off the Hammarlund assembly line over the years, but one of the rarest variations is shown here, and it appears that only about 70 were made. Inspired, no doubt, by high-end home consoles such as the McMurdo Silver, Hammarlund decided to move the set from the ham shack to the living room. So they put it in the cabinet shown here, as seen in the August 1937 issue of Radio World.

But it wasn’t just any cabinet that they slapped it into. As the accompanying article explains, the cabinet was carefully designed for its audio qualities, particularly the bass response. There’s no doubt that the set was a top performer, and I’m sure it sounded good. Since it was destined for the living room, a few modifications were made. For example, even though the set had a BFO for listening to code, the BFO pitch was not adjustable from the front panel.

But it was a flop as far as sales. As the Radio Boulevard site explains, “it just wouldn’t do for hams – it had no BFO on the front and it was too big. It didn’t have the Scott or McMurdo chrome chassis – how could you impress your friends?” The site does have a picture of a nicely restored specimen, owned by AA6S. From the color picture, it does look like a communications receiver thinly disguised as a console. The front panel is faux walnut, and just looks out of place. It’s not quite a communications receiver, and it’s not quite a console.

I’d love to have one in my living room. And as a loyal reader, you would love to have one. But let’s face it, nobody else would want one!

Elizabeth Rickard, Radio Pioneer

Shown here, from the November 1917 issue of Electrical Experimenter,
is Miss Elizabeth Rickard, the first woman to graduate as a radio operator from Hunter College, New York City. According to the magazine, she received her first grade commercial license.

The school had a “very enthusiastic wireless class who are blest with every provision for quickly assimilating the intricacies of radio telegraphy.” The Marconi company had presented the college with standard receiving and transmitting equipment, as well as instructors.

Miss Rickard entered the college’s wireless class in April 1917, and in May of that year, she was detailed to the Marconi school for intensive training. She passed her tests in July, with the highest scores of the class of 20 men and 3 women.

1937 Montgomery Ward Ham Station

Eighty years ago, the October and November issues of Radio News carried a review of the model OR-5 transmitter for the 160 through 10 meter bands put out by an unlikely supplier for ham gear, namely Montgomery Ward & Company.

The reviewer, Everett Walker (whose call was, coincidentally, W2MW, whose 5 meter station we previously featured), posted an overall favorable review of the transmitter: “the small transmitter proved itself an excellent all-band unit on small power. On the higher frequencies it proved a good competitor for the 500 watt transmitter used at W2MW. On the lower-frequency bands it put out a signal that could compete with the normal QRM with more effectiveness than was expected. The transmitter also was tested on 160 meters, not at the writer’s station, but at a nearby station that was equipped with an adequate antenna. Here it put out a good signal and the operator who made the test reported local communication was excellent and more than six “out-of-the-district” stations were worked within a short time.”

He noted that the rig put out 60 watts CW on all bands but 10 meters, where it put out 40 watts.

The rig was geared mostly for the CW man, but the accompanying OR-7 modulator was also available for AM use. In the photo above, the transmitter is at the right, with the modulator in the middle. The accompanying receiver on the left, whose model number is not stated, is also from Montgomery Ward.

1937 Little Giant Cathedral Crystal Set

This ad for a “Cathedral” radio from the Little Giant Radio Company of 1166 Diversey Pky, Chicago appeared in Radio Guide 80 years ago today, November 20, 1937.

The ad praises the set in near miraculous terms, and contains a number of glowing endorsements. Of course, the set is a simple crystal set. The “cabinet”, it turns out, is made of cardboard, and the earphone is mounted permanently right on the back. So to listen, you have to hold the whole radio up to your head. The set had two large alligator clips, presumably to attach to an antenna and ground. But it’s just $2.95, they would send it C.O.D., and your satisfaction was guaranteed.

More informaton, and a picture of the set, can be found in Volume 2 of Crystal Clear: Vintage American Crystal Sets, Crystal Detectors, and Crystals. (Volume 1 and Volume 2 of that set are both available on Amazon.) You can also see some more photos of the set at this link.

US Army Signal Corps, 1942

Signal Corps mobile radio unit.

Seventy-five years ago this month, most of the November 1942 issue of Radio News was devoted to the U.S. Army Signal Corps, and included dozens of photographs, including the color photos shown here. The photos themselves were taken by Signal Corps photographers, which comprised a branch of the service.

Here are a few of them, showing various phases of both wireline and radio communications.

Command car equipped for both voice and code communication.

Operation of handheld radio from Jeep, probably around 50 MHz.

Radio-equipped halftrack.

Students receiving instruction on portable transmitter. Note operating frequencies of ___ kHz.

Students receiving instruction on portable transmitter. Note operating frequencies of 2300, 2900, and 3400 kHz.

Operating radio from concealed position with hand-driven generator.

Operating four-band portable field set.

Field telephone in operation.

Field telephone switchboard.

Placing telephone lines.

1933 One-Tube “Triflex” Shortwave Receiver

As our loyal readers are aware, we often get off on tangents here at OneTubeRadio.com, but we always try to get back on track by showing actual One Tube Radios. And the one we offer today has all the hallmarks of being an excellent performer, covering the range of 10-200 meters.

This is a one tube radio, since it uses a single 6F7. But we’re cheating a little bit, not only because it’s a dual tube, but because the two halves of the tube are actually doing the work of three tubes. The 6F7, which is still readily available at a reasonable price, consists of a pentode and a triode in the same envelope. In this circuit, the pentode is used as an RF amplifier, with the triode serving as the regenerative detector. But through the magic of “reflexing,” the pentode is then used a second time to serve as an audio amplifier. The result is that the set gives the performance of three tubes, while only using a single tube.

The circuit originally appeared in the November 1933 issue of Shortwave magazine, in an article written by “well known shortwave engineer” Clifford E. Denton, who dubbed the set the “Triflex.”

For those wishing to duplicate the circuit, parts, or reasonable substitutes, should be readily available. The new-old-stock tube can be found at this link. You’ll probably need to make the plug-in coils yourself, but you’ll find helpful hints at this post. Most of the other parts can be tracked down at my parts page.