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.
Sixty 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.
Eighty 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.
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.
Eighty years ago this month, the February 1940 issue of Radio Retailing carried this ad for the Admiral model 12-B-5, a five tube set that covered both standard broadcast (including police at the top of the dial) and shortwave signals from 5.65 to 17.1 MHz.
With Europe at war, this inexpensive set would pull in the news straight from the warring powers. I wasn’t able to find much information about this set, but it looks like an “All-American Five” with the shortwave band added. It probably did an adequate job with the strong stations, and at $12.95, it was modestly priced for a shortwave set.
A hundred years ago this month, the February 1920 issue of Boys’ Life asked the boys of America if they had a wireless station, and offered these two receivers. Both tuned 200 – 2500 meters (120 – 1500 kHz). Each included the loose coupler, radiometer, headphones, and hardware for the antenna and ground. The Moded 4007, selling for 28.00, included a crystal detector. Model 4008 was identical, but used an audion tube for the detector. It sold for $48.
The ad promised that the set could be up and running within hours. The crystal set was said to have a range of 300 miles under ordinary conditions, with the audion set being capable of pulling in stations up to a thousand miles away.
The manufacturer, the A.C. Gilbert Company, is the same one which is famous for erector sets, chemistry sets, and other tools for young scientists. While the company no longer exists, the brand name is still in use. The set in operation here is similar to, or possibly the same, as the one we previously featured, delivered by Santa Claus in 1919.
Shown here, from the February 1945 issue of Radio Craft, is a compact one-tube shortwave set dubbed “The Ultra.” It’s a superregenerative set covering 10-120 meters using a 117ZP7-GT tube. One half of the tube is the rectifier, with the other half serving as the superregenerative detector. The magazine notes that the set features post-war details such as phosphorescent panel marks. These are made from glow-in-the-dark paper coated with calcium sulphide which is carefully applied to the panel. After being exposed to the light, the markings will then glow in the dark with a purple hue.
The set is shown here with a bent antenna, and the author notes that this antenna is sufficient for strong stations. He cautions against use of an outdoor antenna, as the set will radiate and interfere with other nearby receivers. He suggests the use of one stage of RF amplification if an outdoor antenna is used.
One shortcoming of a superregenerative receiver is that it’s practically impossible to listen to code. When the key is down, the receiver is silent, and when the key is up, the receiver is making a loud rushing noise. Since this is the exact opposite of how it should sound, the author acknowledges that this is a shortcoming. But for AM signals, it would appear that this little set would really pull in the stations.
With Canada’s men off to war, it was up to the women to work in war industries, as shown by this ad from the Toronto Daily Star 75 years ago today, February 7, 1945.
The ad doesn’t identify the company, but it’s a well-established organization that manufactures radio tubes. Women were needed full time to work as assemblers, and the work promised to continue after victory.
Application was to be made at an agency located at 832 Bay Street, Toronto.
Sixty years ago this month, the February 1960 issue of Electronics Illustrated carried the plans for this one-tube regenerative shortwave tuner. The article was part 6 in the magazine’s build-it course, and the new tuner was designed to plug into the existing projects, which already included AM and FM tuners. For that reason, this receiver contains no power supply or audio amplifier. The cord with the 8-pin plug was keyed to fit the rest of the project, and the shortwave tuner took the place of the FM tuner.
The circuit used a 6BC5 tube. One notable feature is that the regeneration was taken from the screen grid of the tube, rather than the plate. The regeneration control was a voltage divider which varied the positive voltage to the screen.
Since the article was part of a course, in addition to the exact schematic diagram, it also included a simplified diagram along with an explanation of each part of the circuit. From most browsers, click twice on the image for an enlarged version.
Here is the actual schematic for constructing the receiver:
