50 Years of Home Radio
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According to Radio-Electronics magazine editor Hugo Gernsback, 1955 marked the 50th anniversary of "home radio." You would be excused for maybe thinking the world's first home radio set was one of the early "tombstone" style tabletop radios in a stylish wooden case, with a dial on the front for tuning one of the relatively few (at the time) AM stations, and sometimes even shortwave. In actuality, it the TELIMCO Wireless Telegraph Outfit; the only audio signal it emitted was fixed tone indicating a dit or a dah. Music and speaking came a couple years later. Pittsburgh radio station KDKA* is famously the first commercial radio broadcaster, which began operation in 1920. Here are some KDKA articles: Photographic History of Radiotelephony, Half a Century of Electronics Publishing - 50th Anniversary, New Antenna to Multiply Field, Mac's Service Shop: How it Started, Men Who Made Radio - Frank Conrad. 50 Years of Home Radio
By Hugo Gernsback A half-century ago, the first radio for the public's use and enjoyment was marketed. Differing vastly from today's radios in construction and function, it opened the field of radio for private interest and amusement rather than commercial communications use. The year 1955 marked the 50th anniversary of the first home radio sold to the public anywhere in the world. It was not radio as we know it today because in 1905 there was no commercial broadcasting. But wireless had been going strong for several years and amateur radio too had just begun. Marconi and other pioneers were transmitting intelligence by the dot-and-dash method; indeed wireless in those days was rapidly forging ahead. The public at large knew little or nothing about wireless before 1905, except what they read in the papers and in magazines. As for owning a wireless home set, it had not as yet been born. Previous to 1905, in 1903-04, the writer had been working on a small portable transmitter and receiving outfit which he felt could be sold to the public. It took several years to perfect it and make it foolproof so it would work under practically all conditions. It had to be low in cost so everyone could buy the outfit. This ambition was realized some time in 1905. After making a number of models the writer began to market the first home or private radio set ever sold to the public. As there were few wireless stations in the country, it became necessary to sell a transmitter, too, so amateurs could set up a transmitter and receiver at home. Then while one person was transmitting signals, the other could receive them. Or the transmitter could be set up in one room and the receiver would ring a bell in the other room without any intervening wires whatsoever. The outfit that accomplished all this was known as the TELIMCO Wireless Telegraph Outfit. TELIMCO is a contraction of the first letters of the writer's old pioneer firm, The Electro Importing Company (E. I. Co.), which became famous between 1904 and 1915 as the first radio mail-order house in the world. Only comparatively few sets were sold in 1905. But in 1906 the little outfit went into quantity production and was sold through many large outlets, including such famous stores as Macy's, Gimbel's and F. A. O. Schwarz, the country's largest toy establishment. Incidentally, it was first advertised in the magazine Scientific American in the issue of Jan. 13, 1906. This was the first home radio set advertisement to appear in print anywhere. The writer well remembers the incredulous looks of many of the store owners when they were first approached to buy "wireless sets." It was necessary to make a demonstration in each case before anyone would stock them. The complete set, both receiver and transmitter, at first was marketed for $7.50. This was raised later on to $10, at which price most of them were sold. The photograph shows an exact replica of the original outfit, built by the writer, to commemorate the 50th anniversary of the first home radio set. The transmitter, with the three dry cells and key, was composed of a 1-inch spark coil. The "1-inch" here means that the coil threw a 1-inch spark through free air, between wire points. Mounted on the spark coil, on two metal standards, were two brass oscillator balls between which a small blue spark jumped the 1/8-inch gap. The spark coil had a fast vibrator so that every time you depressed the key a spark would jump between the two balls. Depressing the key for a short period would give a dot, a longer period would give a dash. The receiver was a 75-ohm "pony" relay which had to be so sensitive that if you blew your breath slightly against the armature its contacts would close. There was also a single dry cell and the all-important coherer. It was simply constructed of two large, double binding posts through the bottom holes of which passed two silver-plated brass rods. A glass tube, placed between the two binding posts, was slipped over the two brass rods. These silver-plated 1/8-inch metal rods fitted the glass so that there was extremely little or no play. The two rods were separated about 3/16 inch, forming a gap. This gap was filled with the "soul of the set" - the coherer filings, composed of 90% coarse iron and 10% coarse silver filings. By shaking the mixture well it was ready to be used. The filings had always to be loose, never packed tight. The decoherer - an ordinary house bell - was mounted so that the clapper of the bell would strike against the glass tube of the coherer at the exact spot where the filings were. If the diagram is studied, it will be seen that every time the relay closes its contacts, the bell will ring through the single cell. Now, if you depress the key at the transmitter, the two aerials (aerial and counterpoise) will emit radio waves. Curiously enough, the waves which the writer used 50 years ago were of the very short variety (above 30 megacycles) to which modern radio has come back. The two aerial wires of the transmitter measured less than 1 1/2 feet. Inasmuch as the coherer is directly in the receiver aerial circuit, the filings offer a very high resistance. But under the onslaught of the radio waves they instantly become an excellent conductor - as if they now were a solid conductor. The relay, in the same circuit, now goes into action, attracting the armature which closes its contacts. This sets off the decoherer bell which rings and shakes up the coherer filings. These now fly apart - they decohere - and the coherer becomes nonoperative until the next wavetrain comes along. Thus every time you press the transmitter key, the bell at the receiver rings. It rings as long as you hold the key down. A long ring is a dash, a short one a dot. You can pick up the receiver and walk to· the next room, yet the bell sounds without any visible connection. Even through thick walls, signals still come in. One of the things that bedeviled us in the early days was sparking at the relay contacts. This would set up electromagnetic waves and often the outfit gave no clear signals; sometimes the bell would ring for seconds after the signal. This was overcome by putting a 5-μf capacitor across the relay points. The range of the TELIMCO Wireless Telegraph Outfit was between 300 to 500 feet when used without ground connections. By using an elevated aerial 50 to 100 feet in length and by grounding one side of both transmitter and receiver to a water or gas pipe, the range was easily increased to one mile. Indeed, hundreds of people who bought the outfit at the time reported excellent reception even over greater distances, but these, of course, were exceptions. Note that this set used no tuning whatsoever. A curious thing about this little outfit today is its strange effect on radio people who never heard of the ancient spark coil and coherer sets. Young radiomen, who have never seen one of these outfits, are usually very much perturbed and astonished when the writer demonstrates it. The reason of course is that people have difficulty realizing that with a little three-dry-cell transmitter it is possible to ring a bell through intervening walls while the novice holding the receiver. Radiomen today think of devices which operate relays as being relatively large and find it hard to believe that such a small portable transmitter and receiver could do the work. It is conceivable that some time in the future these same instrumentalities may still find a use in modern radio and electronics which may not be apparent today. The TELIMCO outfit here described has recently been acquired by the Henry Ford Museum of Dearborn, Mich. It was donated by the writer. It will be permanently exhibited in the radio section of the museum.
Posted October 13, 2022 |
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