The plans for this handsome two-tube set appeared 80 years ago this month in the March 1944 issue of Radio Craft magazine. The author had a broken midget set with a cracked case, one bad tube, and some loose connections, but he was able to use the parts to make this portable TRF set.
For a cabinet, he found some clear plastic. The result, despite wartime parts shortages, was a radio almost as good as the donor.
A hundred years ago this month, the March 1924 issue of Radio News showed the holy grail of crystal sets: One that would provide the elusive loudspeaker volume without any tube amplification. It didn’t require any electrical power, but as the hand crank indicates, it did require mechanical power.
The device was dubbed the Frenophone, and was invented by S.G. Brown of the company S.G. Brown, Ltd., of England. It worked as follows, referencing the diagram at left:
An ordinary Brown telephone receiver, A, with adjustable magnets, is attached to a metal arm pivoted at B, and weighted at the end with counterbalance C. To the reed D and the receiver are attached the steel needle E to whose end is fastened a small disk F covered on the bottom with cork. This small disk is directly above a perfectly level glass plate G. The glass plate, in turn, is mounted on the shaft of a phonograph motor so that it may be slowly revolved. The disc F, as shown in Fig. 2, is suspended by threads H near the edge of the glass plate G. The two threads terminate at the center of the diaphragm L which is the diaphragm of the loud speaker.
According to the magazine, the instrument required very fine adjustment. But once it was set up, it worked satisfactorily, and frequent adjustment was not necessary. If you want to see one in person, you can do so at this London museum.
Eighty years ago, these gentlemen are disassembling an old radio to salvage the parts within. There was a war going on, and those old parts would provide many useful materials. The March 1944 issue of Popular Mechanics reminded them to unsolder all fixed resistors and capacitors, rather than clipping the leads. It also reminded them to save the coils, sockets, and screws in separate compartments in their junk boxes.
The fashionable headgear shown here from a hundred years ago is being donned by an engineer at WDAP in Chicago. The station had these so that the quality of the station’s transmission could be checked at any time anywhere in the studio. The crystal set was mounted on a pair of headphones, which meant that there was no need to sit down at a standard receiver.
Later that year, the station was purchased by the Chicago Tribune, which changed the call letters to WGN, for World’s Greatest Newspaper.
These images appeared in the March 1924 issue of Popular Mechanics.
Eighty-five years ago, radio repairman Lewis P. Evans of Chicago’s Evans Radio Laboratory brought along a camera on every service call. He would snap a picture of the house, or if he was lucky, a picture of a child, or even the family dog.
He would hold on to the pictures for a few months, and then send them to the woman of the house, with the shop’s address on the back. He reported that a woman can’t resist a picture of her own home or someone in her family. The picture would be saved, or perhaps placed in the family photo album. And when the radio needed service, they would know exactly where to find the shop’s address.
This feature appeared in the February 1939 issue of Radio Retailing. According to this 1936 newspaper advertisement, the shop’s address (presumably the one on the backs of the photos) was 7152 S. Exchange Ave.
This schematic for a code practice oscillator appeared in QST 70 years ago this month, February 1954. The observant reader will notice that something seems to be missing.
That’s right. There’s no apparent source of B+ power. The only power connection is to the filament of the tube. But it works anyway! According to an editor’s note, the circuit shows 0.2 volts between the cathode and plate, derived from the initial velocity of the electrons.
According to the same note, the only other circuit that works without any apparent plate voltage is a Tri-Tet crystal oscillator, This is explained in more detail in an article in the May 1941 issue of QST. According to that note, the oscillator “will run merrily without plate voltage from an external source so long as the circuit is complete.”
This code oscillator was designed by long-time ARRL staffer Lew McCoy, W1ICP, who then held the title of Technical Assistant. He noted that the electric buzzer was the traditional method, but “if you don’t live alone, the sound of an electric buzzer may soon grate on the nerves of the family or neighbors.” This inexpensive circuit allowed practice while still preserving peace at home.
The novel method of powering the oscillator meant that it could be built for less than six dollars, less than half the cost of commercial code oscillators. And after licensing, those parts could undoubtedly be put to use in other projects.
McCoy noted that while the circuit worked with all 6J5 tubes he tried, it was possible that a particular tube might not. In that case, the advice was to try another. He noted that the 6F6 pentode he tried, with plate and screen tied together, also worked.
The oscillator took care of the beginner’s need for sending practice. For receiving, he pointed out the W1AW code practice sessions, but also included a list of other stations with scheduled code practice. Many of these were operating on 10 meters. For example, W0BOL was sending code practice on 29.2 MHz Tuesday and Wednesday evenings from 1130 Delaware Avenue, St. Paul, MN.
Eighty years ago this month, the February 1944 issue of Radio Craft gave some description of the automatic gun director system illustrated here. The system consisted of a computer (undoubtedly analog) that directed the gun exactly where to fire. The path of the plane was plotted by two telescopes, whose operators kept the plane in the cross hairs for a few seconds, to plot the aircraft’s location, speed, and direction. Height was measured in a similar manner, and the computer had inputs for wind direction and velocity, muzzle velocity, and air pressure. The result was a gun that was able to aim itself to the spot where the plane would be when the shell arrived.
This combination radio-intercom system was the latest thing 75 years ago. It could be used as a regular broadcast receiver, from either its own speaker, or the extension unit in another room. And at the push of a button, it could be used for two-way communications. The set had four tubes, said to be quick heating.
It appeared in the January 1949 issue of Popular Mechanics.
The duo behind the counter here are Dick Hall, W5EIB, and his wife Lillian Hall, W5EUG, owners of R.C. & L.F. Hall, 1015 Caroline St., Houston, Texas.
Their business began when they found a lack of interest by local dealers for hams, and Dick began stocking a few parts in his home. As the stock started to overtake their entire house, they moved to a downtown location. As they anticipated American entry into the war, their business focused on industrial and marine parts. When war came, they knew the whereabouts of most amateur transmitters and receivers in the area, and facilitated sales of that equipment to the military.
The Halls discovered that dealers and hams don’t really mix. The dealer, seeking marine and industrial parts, knew just what he wanted, whereas the hams wanted a place that talked their language. They anticipated a big future for their business after the war, as hams came on the air, and as FM and TV stations would create new markets.
The picture and accompanying article appeared in Radio Retailing, Feburary 1944. This eBay listing shows a 1946 ad for their business, which by then had locations in Beaumont, Dallas, and Galveston, in addition to the Houston store, which was then at 1306 Clay Avenue.
Eighty-five years ago, the February 1939 issue of Radio Craft shows how to wire your house for radio. And like Mr. Green, you could be serene knowing that there was one in every room. Actually, there was only one radio, a top-of-the-line RCA Victor model U-130. Speakers were mounted in each room. But in addition, the set allowed the use of a wired remote control, so controls were mounted on the walls of most rooms. But if walking over to the wall proved too stressful, there was also an armchair remote, which could be plugged in to a nearby socket.
The installation also incorporated a set of Model 446 Aristocrat “TELECHIMES” by General Kontrolar company, Inc., which could be used to elegantly page family members throughout the house.