Category Archives: Radio history

1968 Radio Shack Battery Kit

1968AugRadioTVExpFifty years ago, the August 1968 issue of Radio-TV Experimenter showed this interesting offering from Radio Shack, a hobbyist kit for assembling two D-cell flashlight batteries.

By all appearances, the finished product is identical to the store’s pre-manufactured “heavy duty” carbon-zinc battery. The only difference is the price, as you apparently had to pay a small premium for the privilege of putting it together yourself:  The kit cost $1.25 for two batteries, but the manufactured article, as shown below in the 1968 Radio Shack catalog, were available four for 98 cents.

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Despite the slight extra charge, there is something alluring about making a product at home that’s indistinguishable from the factory version (as is the case with this currently available AM-FM radio kit).  For students thinking about making a homemade battery today, see our earlier post about making a reasonably useful battery suitable for emergency use, or this hundred year old idea for making a homemade flashlight, battery and all.



1937 Zenith Robot Dial

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In 1937, the Zenith Robot Dial was apparently a big deal, as evidenced by this photo in the August 1937 issue of Radio Retailing.

According to the caption, the display was in the window of Zenith Radio Distributing Corp. in Chicago, and the “ten-foot high dial tuned by a pretty girl stopped traffic.”



1938 Dayton, Ohio, Emergency School of the Air

1938Dec3RadioGuideThis teacher and students  are holding class in 1938 in the studios of WHIO, Dayton, Ohio, as shown in the December 3, 1938 issue of Radio Guide.

The teacher was apparently working without pay, but most of her colleagues weren’t quite so generous. The Dayton Board of Education “ran out of funds,” and the city’s 1300 teachers refused to continue without pay, leaving the 34,000 students without the possibility of public education. The station’s owner stepped in and volunteered the station’s facilities to cope with the emergency.

In cooperation with the superintendent, the station quickly revamped the station’s schedule to broadcast emergency lessons. Four periods of instruction were organized, supplemented by educational programs from the networks. As a result, students were able to spend a couple of hours per day receiving expert instruction. The Emergency School of the Air included classes in English, Biology, Chemistry, General Science, Physics, Vocational Guidance, Latin, French, Spanish, German, Bookkeeping, Geography, American History, Mathematics, Civics, Art, and Music.



1938 Pyro Pantagraph

1938AugRadioCraftThis ad for the Pyro Pantagraph appeared 80 years ago this month in the August 1938 issue of Radio Craft. For a mere $2.75, the enterprising young man or woman could go into business and “burn your way to extra dollars.” The burning tool was designed to burn designs onto leather, wood, cork, bakelite, or even gourds. The electric pencil plugged in to any 110 volt outlet, with “plug and cord furnished as part of equipment.”

Pantograph. Wikipedia animation.

But what made the set special was the pantograph, which allowed designs to be reproduced in the original size, enlarged, or reduced, as illustrated by the animation here.

As far as I know, the Pyro Pantagraph is no longer available, but inexpensive wood burning tools such as the one shown here are readily available, as is a pantograph such as this one.  Most modern pantographs appear to be made of plastic, so you’ll need to figure out a way to affix the burning tool.  And most of the negative Amazon reviews are fixated on the fact that the instructions are in Chinese.  But we’re confident that our readers are smart enough to figure these things out themselves, and have no need for the instructions.  You can still burn your way to extra dollars, or this could be the basis for a most interesting science fair project.



1918 Combination Telegraph Sounder/Key

1918AugEEThis ad from the August 1918 issue of Electrical Experimenter magazine shows an interesting code practice set which appears to be a combination key and sounder, for the low price of 25 cents (plus six cents for the catalog the company wants to get in as many hands as possible.

The ad contains the copy: “Impossible–you say. Quite so.” I’m still not sure exactly how it’s supposed to work. My best guess is that there’s another contact not visible behind the front binding post, and the key is wired in series with the coil. The sounder and the key would have to be able to move independently, which I guess is possible if it’s flexible enough and the center mount is firmly attached. Hooked to a battery, the sounder would then click whenever the key is depressed.

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According to the ad, two such units can be connected, with a range of up to six blocks. This would require the key to be shorted out, and there doesn’t appear to be a convenient way of doing that, other than perhaps just holding down the key while receiving.

The ad reminds readers that telegraph operators are scarce, and that Uncle Sam needed thousands. For the entrepreneurially minded young men, the ad points out that boys are ordering 6-25 of them and selling them to their friends like hot cakes for 30-40 cents.

Even though the sounder would be most useful for learning American Morse for use on a landline telegraph, the text around the key is in International Morse, and reads:  EICO NY.



1938 Progressive Receiver

1938AugPMThe young man shown here, now in his early 90’s, is pulling in a strong local broadcast station with the help of a simple crystal set shown in the August 1938 issue of Popular Mechanics.

That, by itself, isn’t particularly remarkable, since a lot of kids constructed a crystal set.  But this young man has the added satisfaction of knowing that within a month, he’ll also be pulling in the weaker stations, and he’ll get loudspeaker volume on those strong stations, when he upgrades the set.  The construction article is actually a two-part article to be continued in the September issue showing two upgrades for the “progressive” receiver.

The first upgrade will replace the crystal detector with a tube.  A few additional parts will be required, but thanks to careful planning, all of the original parts (with the exception of the 12 cent detector) will be re-used.

1938AugPM1And as soon as he gets the one-tube broadcast set going, he’ll be able to get to work on the final upgrade, which will allow him to pull in the short waves by adding a few parts.  The original wooden chassis will be used for all three receivers.

As you can see from the pictorial diagram, the crystal set is a very basic model.  The only interesting angle is that the antenna coil features a primary that can be adjusted by sliding it over the secondary, allowing the set to be peaked for the maximum sensitivity.  When the set is upgraded (using an RK-43 tube), the primary coil becomes the tickler coil of a simple regenerative receiver, with the other half of the tube serving as audio amplifier.  The upgrade to shortwave isn’t shown, but we promise to include it in a later post.



1938 Majestic Charlie McCarthy

1938AugustRadioRetailerEighty years ago this month, the August 1938 issue of Radio Retailing carried this ad for Majestic’s Charlie McCarthy radio. It reminded dealers that the set wasn’t a novelty, but a high-quality six tube radio. The set was to be marketed in theaters, and dealers could reserve their share of the profits by acting fast.

The set is still popular with collectors, and you can see a restoration in progress at this video:



1938 Knapsack Portable

1938AugPS1938AugPS2The young man shown here is enjoying radio on the go thanks to the four tube portable knapsack set shown in the August 1938 issue of Popular Science.

Worn like a life jacket, the set allowed the wearer to tune in broadcast stations while biking or hiking. The radio itself is worn in front, with the loop antenna on the back, and with the batteries at the side. Featherweight headphones were recommended for listening long periods without fatigue.

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Wartime Tube Shortages

1943JulyRadioRetailingToday2Wartime parts shortages in 1943 meant that radio repairmen had to improvise to make do with what was available, and magazines were full of tips to allow substitutions.

The diagram shown here was sent in to the July 1943 issue of Radio Retailing Today by radio serviceman M.G. Goldberg of 142 E. 4th St., St. Paul, Minn.

Goldberg noted that tubes for the standard “All American Five” circuit were hard to find, but equivalent six volt tubes were still available, and that 6 volt filament transformers were also fairly easy to come by in most areas. So one solution to the problem was to replace the series-string tubes with 6 volt equivalents, as shown here. This particular version meant that the tube sockets could be kept as-is, other than rewiring the filaments. The article also suggested other possible substitute tubes, although other substitutions would require rewiring the sockets.

1928 Beginner’s Crystal Set

1928JulyRadioNews2Ninety years ago this month, the July 1928 issue of Radio News carried the plans for this simple crystal set. The magazine noted that the multi-tube sets could pull in distant signals, but there was something to be said for the thrill of receiving a local station on a simple receiver built at very low cost. It noted that the majority of receivers in Europe and other parts of the world were still crystal sets, and that the crystal set was actually superior when it came to the quality of the signal received, since there was no distortion caused by the tubes. And added bonus was the lack of operating cost, since not battery was required.

The magazine especially reminded parents that if a boy was interested in radio, then a good way to keep him out of mishcief was to get him started building his own. The simple set would pull in the local stations, and also give him insight into doing things for himself.

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