Seventy years ago this month, the August 1952 issue of Popular Mechanics showed how to build this extremely compact broadcast receiver. The set was named “The Salesman’s Pal,” as it was designed to meet the needs of the “honest-to-goodness salesman–on the road most of the time,” although it was also suitable for the once-a-year vacationer.

The set was a typical “All-American-Five” AC-DC set, but was small enough to conveniently slip inside a briefcase. Two recently available parts made the small size possible. The first was a Centralab Audet PC-150 printed circuit unit, which we might today call a predecessor of the integrated circuit, as it contained several resistors and capacitors in the same package. The other, which became ubiquitous in later portable radios, was the “Ferri-Loopstick,” a ferrite core antenna coil.

The article pointed out that while the set was not difficult to build, the limited space meant that it was not intended for beginners.

By 1922, it was pretty clear that radio was soon going to be a phenomenon to be enjoyed by all. Retailers were starting to pop up, and Omaha, Nebraska, was no exception. This ad appeared a hundred years ago today in the Omaha Morning Bee, July 30, 1922. If you were in Omaha, then the place to be was at the southeast corner of 17th and Howard, where you would find the Radio Apparatus Company. It was no longer necessary to go out on disagreeable evenings. Your new radio could bring you music, lectures, and concerts at will. You could stop in for a demonstration, or if you called, they would be happy to arrange one in your home.

Seventy-five years ago this month, this ad from Federal encouraged radio dealers to make some extra profit by upgrading their customers’ portable radios. Most such sets operated off batteries as well as standard household current. The radio itself had four tubes, along with an additional rectifier tube for use at home, in this case a 117Z6. The low-voltage tubes came to life almost immediately, but the rectifier took some time to warm up. By replacing it with a selenium rectifier, this problem was solved. And even though selenium rectifiers are famous for their catastrophic failures (which produce malodorous and toxic fumes), they probably lasted longer than the tube, and probably outlasted the radio in most cases.

The age of selenium rectifiers lasted through the 1960’s, when they were replaced by silicon diodes.

The ad appeared in the July 1947 issue of Service magazine.

With radio, as with everything, there’s a right way and a wrong way of doing things. A hundred years ago this month, in the July 1922 issue of Popular Science, Armstrong Perry gives some pointers on how to set up your radio receiving station the right way, and he includes the examples shown above. He concedes that the second station might be highly efficient, but from not planning things out right from the beginning, it is “no ornament to the household.”

A hundred years ago this month, the July 1922 issue of Science and Invention carried the plans for this, which the magazine called the “simplest radio receiver.” The plans had been sent in by Leon Webster, who won $50 in the process, as the third-place winner of the magazine’s radio design competition.

According to Webster, the set could be constructed by a twelve year old boy, and a great deal of pleasure could be obtained. All that was needed was an outside antenna and ground, a tuning coil, condenser, and detector.

The condenser consisted of one from a defunct Model T spark coil, and the detector was a piece of galena or silicon. The coil, as shown here, was homemade on a piece of wood. The set would work with an old telephone receiver, but for better results, a 1000 ohm headphone was the better option.

A hundred years ago this month, the July 1922 issue of Popular Science explains how the Seaman’s Aid Society of New York deals with the problem of medical emergencies at sea, in the form of a radio doctor whose services can span half the Atlantic.

Sixty years ago, this listener was probably listening to a record with the player on the left, but perhaps she is pulling in a broadcast or even shortwave program with the identical unit on the right.

One way or another, she is listening to a Sterephone (note the “e” in the middle rather than an “o”) that she purchased from Hoffman Electronics in Los Angeles for about $80. The one on the left is lying on its side, and in that configuration, it’s a portable record player capable of spinning both 45’s and 33’s. But standing upright, it’s a radio covering the broadcast band and 3.9 to 12 MHz shortwave.

It’s shown here in the July 1962 issue of Electronics Illustrated.  While the magazine doesn’t give the details, it appears to be Sharp’s model BXG-370.  The set was powered by four flashlight batteries, or could run on an optional AC adapter.

This compact 80 meter transmitter designed especially for the novice appeared 70 years ago this month in the July 1952 issue of Radio-Electronics.

The two-tube circuit used a 6AQ5 as a Pierce crystal oscillator, with a 1625 serving as class-C final amplifier. The 1625 is the 12 volt version of the venerable 807 tube, and according to the article, it was possible to buy several of the on the surplus market for the price of one 807. Since a separate 12 volt power supply would be required for that tube, the article suggested using two 6 volt filament transformers in series.

According to the author, good results were had with a 20 foot antenna at 12 feet.