John Beckman - W4BTX HAM RADIO "A PAST TIME FOR A LIFETIME"
Back in the '70s and /80s we proudly hung our handi-talkies on our belts and had the accessory mic clipped to our shirt pockets. It was pretty cool. Now, the w;hole transceiver (with lots more features) will fit in a shirt pocket. It wasn't always that simple. In a recent ARRL was an interesting article from 1936.
Since the advent of wireless technology, efforts have aimed at condensing the size of the necessary equipment to permit ease of transport, mobile installation, and radios that could be hand carried, slipped into a pocket or -- in this case -- carried on the belt. Hugo Gernsback's Radio-Craft for December 1936 included the article, "How to Make the World's Smallest 3-Tube Radio Set" by Arthur Miller (likely not the playwright). It details how a clever radio crafter could construct a set worn on a belt around the waist and -- in this case -- with the antenna worn on the head in the manner of an old-time banker's eyeshade. The individual wearing such equipment today likely would not only have to endure considerable pointing and laughing but would raise the alert level at any airport TSA checkpoint.
(Click on the small pix for larger Picture)
Vacuum tubes of the day were not too sensitive, required separate voltage sources for filament and plate, and were pretty hard on batteries. The filaments for the three tubes came from "a liquid unspillable storage cell" (i.e., rechargeable) to supply the necessary 2 V. The article says this battery should last from 7 to 10 hours and came "with an oiled silk bag and fits in the hip pocket." This was the sort of futuristic innovation that Gernsback typically featured in his publications, and the entire December 1936 issue of Radio-Craft is worth perusing.
"When using this 'Belt-Radio' the wearer is quite unmindful that the latest news or dance music is coming from an ultra-midget receiver which is actually being worn on the belt!" the article exults. "And it takes only a minute to put the whole equipment on -- and less to take it off!"
According to Miller's article, building the three-tube set was easy. "The loop aerial is wound on a cardboard disc 13 ins. in dia," it explains. "Litz wire is used and 22 turns are interlaced around the 9 ribs." No mention of gauging hat size. The article concedes just to "one disadvantage" in having to wear the antenna on one's head. "The 4-ft. cable connecting it with the receiver acts as a capacity and restricts the tuning range of the set," it explains.
The set tuned the AM broadcast band, and with the antenna on the head, directionality was less of an issue. While it might look silly to us now, project ideas such as this helped advance the radio art toward the technology we use and enjoy today.
If you click on the underlined link above you will go the whole 1936 issue of Gernsback Radio-Craft magazine.;
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