The gentleman shown here is listening to one of the first pocket-sized radios, the plans for which were shown in the July 1950 issue of Popular Science.

The magazine notes that you don’t have to carry your portable radio–you can wear it. The receiver is so small that it will slip into your pocket, and you’ll hardly know you have it with you. The set was a four-tube superheterodyne that would pick up everything on the dial, thanks to four subminiature tubes.

The article did state that one needed to have “a little practice in radio building” in order to put it together. Indeed, the mechanical construction looks very challenging, trying to squeeze all of the parts into a small makeup box.

Unfortunately, the project is challenging partly because it’s unclear which tube is which. The set calls for four tubes: 2G22, 2E32, 2E42, and 2E36. Unfortunately, they’re not labeled on the schematic, and the text gives only a few hints. The 2E36 is the audio output, the tube on the far right. I think the other three, from left to right, are 2G22, 2E32, and 2E42, but I’m not positive. In any event, the tubes are taped to the sides of the IF transformers to squeeze everything into place. Of course, it probably doesn’t matter, since these tubes are probably all unobtainium.

Update:  A reader sent us a copy of the page below, which shows the missing tube numbers.  Apparently, the top of the page was cut off, but is visible in the scan below.  Thank you!!

Yesterday, we posted this quiz from the July 1940 issue of Radio Craft magazine. Based upon the symptoms shown, what was wrong with the radio?  As promised, here’s the answer:  R1 is open.  Here’s a more complete explanation:

We’ll give you 24 hours to think about it, and then post the correct answer tomorrow.

Would you have made the grade as a radio technician 80 years ago? You can find out from this quiz in an ad in the July 1940 issue of Radio Craft magazine. Based upon these symptoms, can you figure out what’s wrong? If you graduated from National Radio Institute’s home study course, you would undoubtedly identify the problem right away.

For a larger version of the image, click on it.  Then, in most browsers, click on it again to enlarge.

We’ll give you 24 hours to think about it, and then post the correct answer tomorrow.

A hundred years ago this month, the July 1920 issue of Popular Science reported that the United States Forest Service had found a valuable ally in the radiotelephone. 42 sets like the one shown above were in operation at remote points in Wyoming, Montana, and Oregon. Range varied from 10 to 300 miles, with about 50 miles being typical.

The article noted that two such stations bore a cost of about $3000. However, that particular circuit covered 60 miles, and a comparable telephone system would have cost over $5000. Even though rangers started with no radio experience, the Service reported that after a few months, they were able to expertly take and send messages.

The trees themselves were pressed into service as antenna supports. At each site, two suitable trees would be stripped of branches and the wires stretched between them. Initially, storage batteries were packed back to the closest town for charging, but gasoline generators had just been installed to save that labor.

Mules, such as the ones shown at right, transported the equipment to its station. But when the trails got too steep for the mules, the rangers themselves carried the equipment.

Seventy-five years ago this month, the July 1945 issue of Popular Science shared this self-explanatory helpful hint for mounting a radio on the wall. Many times, the radio wound up at the wrong end of the room, because that’s where the table was. With this idea, you can mount it wherever desired, and it had a sleek “built-in” look about it.

The magazine did caution that before following this scheme, you should make sure the radio’s cabinet is structurally sound.

Seventy-five years ago this month, the June 1945 issue of Radio Craft carried this schematic for a code oscillator sent in by one Gene Clardy of Fort Worth, Texas. According to Clardy, the circuit’s main feature was its safety, since no high voltages were present. With no possibiity of high voltages on the key or headphones, all possible shocks were avoided.

The set used a 6 volt doorbell transformer to light the filament. The secondary of the transformer was also rectified by half of the tube to supply the B+.

Fifty years ago this month, the June-July 1970 issue of Science and Electronics  carried this project, which itself dated back another fifty years. It’s a simple crystal set, but the most interesting feature is the tuning capacitor, which is a book-style condenser. It consists of two blocks of wood, each with a layer of aluminum foil carefully glued to one side. These are hinged together, and the set is tuned by turning a screw to open and close the book.

Astute readers might remember similar capacitors used in this 1944 crystal set and this 1942 tutorial on making parts at home.

I don’t know much about the provenance of this photograph, other than that it was taken in Atlanta about a hundred years ago. What is clear from their expressions, however, is that the two girls in the foreground obviously understand the magic of radio. Chances are, they had never heard a radio before, but when they heard music coming out of the headphones, they realized that the world had changed. I’m guessing their families were among the first on their block to get their own radio set.

Not everyone gets the magic, though. Many of the others seem a bit skeptical about this new contraption. All I know about this picture is that it appeared a hundred years ago this month on the cover of the June 1920 issue of Wireless Age, and that the caption reads, “members of an Atlanta club who danced to music received by wireless ‘phone.”