vintage radio

Vintage Radio
11:16 am
Thu February 13, 2014

Making Pictures Fly Through The Air

Credit The Early Television Museum of Hillard Ohio, www.earlytelevision.org, used with permission

Television as we now know it, an electronically scanned and reproduced image, was a development of the 1930s. I’ll spend more time discussing electronic TV at a later date. For now though, let’s take a look at what came first, something called electro-mechanical TV. Although it is not my intent to write this series as a chronological history of radio, we have started out by exploring the beginnings of the art, and many readers may find it surprising to learn that the concept behind television came about long before radio itself.

Alexander Graham Bell invented the telephone in 1876. Despite the limited technology of the day, there were those who believed that if it was possible to send sound over wires, why not pictures?

The photoconductive properties of the element selenium had been discovered in 1873 by Willoughby Smith (*1), an English electrical engineer.  Mr. Smith had already achieved wealth and success derived from his development of high quality wire for the telegraph industry. Selenium's electrical conductivity varies with the amount of light that it receives, making it ideal for converting varying amounts of light into an electrical signal.  The more light that it receives, the more electricity it conducts.  Mr. Smith thought that he could use this characteristic to send images over wires. He attempted to focus an image on a number of selenium cells, each cell connected to a corresponding light bulb. The bulbs would in theory reproduce the image that fell on the selenium cells. This is comparable in concept to each cell and bulb representing a single pixel of a modern digital screen, only much bigger. In theory this should work, except that the cells and the bulbs of the day were far too large to produce any resolution.  It would have also required at least one wire for each cell and bulb, requiring an impractical number of wires to send such an image over any appreciable distance. Mr. Smith eventually discontinued his attempts to develop the system.

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Vintage Radio
3:04 pm
Sat January 4, 2014

Order Out of Chaos

A 1922 Atwater Kent Model 1 table radio
Credit John Jenkins/ sparkmuseum.com

While perusing the shopping mall this holiday season in pursuit of last minute gifts, I came upon an advertisement depicting a popular video game. The ad pictured the game as having just two controls; one labeled “ON/OFF”, the other was labeled “MAYHEM”.  Reflecting upon this, I thought that perhaps it would have made for good labeling on radios manufactured during the early 1920s.

Just what would you have heard on the 1922 set pictured here,  or the ones  featured in my recent articles?  Let's take brief look at the history of early broadcasting to get a feel for what the airwaves were like in the beginning. The first major commercial use of radio technology was for communication with ships at sea, and this was done exclusively with Morse code. In the beginning, amateur radio operators could operate whenever and on whatever frequency they desired, also using Morse code.

The first radio rules in the United States were enacted by the US Navy. These primarily consisted of the requirement that all non emergency communication must stop for a period  of five minutes at the top and bottom of each hour during which all stations must listen for possible distress traffic from ships at sea. Back then almost all communication took place on or just below what we now know as the AM broadcast band. There were no assigned frequencies because spark gap transmitters such as the one used on the Titanic splattered energy over most of the band anyway. Although all stations were required to  yield to emergency traffic, if your boat sprang a leak on a busy night at six minutes after the hour you might have a problem.

As the technology progressed, clean transmitters that could be centered on a specific frequency were developed. 400kHz became the first frequency assigned exclusively for distress traffic. Further developments led to the ability to modulate the radio signal with audio. This opened new opportunities not only for marine and amateur traffic, but for broadcasting to the general public as well. By 1912, the airwaves were becoming so overcrowded that the US government enacted legislation giving the Department of Commerce (DOC) the power to regulate radio transmissions (radio act of 1912). The Titanic also played a role in this legislation. The new rules included a requirement that ships at sea must have a radio operator on duty 24 hours a day. The freighter Californian was estimated to have been about 30 miles from the Titanic when it struck the iceberg, about half the distance that the Carpathia was, and capable of reaching the Titanic before she sank. The Californian’s radio man had retired for the night, about an hour before the fateful distress call was sent.

The first broadcasts to the public were made by radio amateurs, who were defined at the time as anyone not conducting land or marine communications for commercial purposes. One of the more notable amateurs  was a Frank Conrad,  who began playing music over his amateur radio station 8XK from a garage in Pittsburgh,  Pennsylvania  in 1916. He began receiving requests to play more music from people listening with crystal radios and soon was borrowing records from a local music store in return for on air promotion. This new broadcasting concept caught on quickly and soon stations were popping up all over the country. As technology improved, transmitters became more powerful. Broadcasters would often increase power or switch frequencies to overpower a potential competitor. By 1920 the airwaves were quite a mess and something had to be done. The DOC restructured radio regulations. A new broadcast class license was introduced. Amateur operators lost their privilege to play music or broadcast to the general public (now they could only communicate directly with other amateurs) and were restricted to frequencies above 1500 kHz that were considered to be "worthless" for serious communications.

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Vintage Radio
8:38 am
Tue December 3, 2013

A Rhode Island Radio

Polle Royal table radio
Credit Paul Litwinovich

This is  a Polle Royal table radio, manufactured by the Royal Radio Corp. of Providence, Rhode Island. I estimate the date of manufacture to be between 1923 and 1925. I have been unable to locate much information about the company other than it was one of the many small manufacturing companies to come and go during the infancy of the radio industry. Many of these small independent radio manufacturers were quite successful for a few years only to fail during the great depression. Many turned out a high quality product. This particular set appears to have been targeted at the higher end of the market and was technologically advanced for its day. It consists of a 5 tube Bakelite chassis using type #01 tubes and a Bakelite front panel featuring silk screened markings with gold leaf paint. The knobs feature machine etched pointers also filled with gold leaf paint. The cabinet appears to be pine or poplar with an ebony stain. Like all radios from this time period, it is a battery powered set, but this gave it the advantage of operation in both the city and rural areas not yet electrified.  Unlike the kit radio that I featured two articles back that was designed to maximize battery life, this set was designed for maximum performance at all times and was probably sold to consumers who were not as concerned with the price of batteries. Although I have not been able to determine the original selling price of the radio, similar high end sets typically sold for a little over $200.00, the equivalent of $2600.00 in today’s dollars [1].

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Vintage Radio
1:00 pm
Mon November 4, 2013

Vacuum in a Tube Enabled Sound from a Box

Credit Paul Litwinovich

In my humble opinion, the vacuum tube rates among the most important technological inventions of the past century. It is considered by most to mark the birth of the electronic age, and until the invention of the transistor in 1947, it stood alone as the heart and soul of just about every electronic device developed.  

Opinion varies over just who should receive credit for inventing the device. The debate focuses on four well known inventors;  Americans Thomas Edison and Lee DeForest, Englishman John Fleming, and the German physicist Wilhelm Conrad Roentgen. For the purpose of discussion, let us define a vacuum tube as a vessel most often made of glass, porcelain or metal, from which as much air as possible has been pumped out, containing a number of electrical elements and performing a useful function. Based on that definition, all of them qualify in one way or another.

In 1895 German physicist Wilhelm Conrad Roentgen discovered that by placing two electrodes in an evacuated glass tube and applying high voltage to these electrodes, that not only would electricity flow through the vacuum, but that x-rays would be generated by the impact of the electrons striking the steel plate. Mr. Roentgen was not the first to observe that electrons could be made to flow in a vacuum, but his invention of the x-ray tube was probably the first useful and practical application of the phenomenon. As a result of his discovery, he was awarded the first Nobel Prize in Physics. Both of the elements in Roentgen’s original tube were unheated. It is not easy to get electrons to flow in a pure vacuum between unheated elements. Fortunately for Mr. Roentgen, vacuum pumps were not of the highest quality in 1895, and traces of remaining gasses became ionized (electrically charged) allowing current to flow.

Thomas Edison invented the light bulb in 1879. He did so by placing a carbon filament in a glass enclosure and pumping all of the air out of it. His early bulb had one major problem. Carbon seemed to evaporate from the filament and deposit itself on the glass, darkening the glass and thus reducing the useful light output. He noticed that more carbon seemed to evaporate from the end of the filament attached to the negative terminal of his power source. A year later he placed a second element in the bulb, a small metal plate near the filament. He observed that electricity would flow through the vacuum from the hot filament to the plate. He was unable to explain this effect but was hoping that the carbon would also be drawn to the plate instead of darkening the inside of the bulb. When this did not happen, Mr. Edison discontinued research on the phenomenon,  but not before obtaining a patent for the “Edison Effect”, hoping that it might have some commercial application in the future.

John Fleming was an engineer, physicist, and professor who taught and lectured at a number of British universities. He presented an important paper on the theory and design of electrical transformers in 1892. He crossed the pond to take a job in  Thomas Edison’s lab and became curious about the “Edison Effect”. Later, while working for Marconi Wireless he began conducting further research and discovered something that Mr. Edison had overlooked. He noted the fact that electrons would only flow in one direction, from the hot filament to the cold plate, and only when the filament was made negative, and the plate positive. In 1904 he patented this device as the “Fleming Valve” for use as a detector of radio waves. The English still refer to vacuum tubes as “valves” to this day. Ironically,  his first vacuum tube was replaced by the first “solid state” device, the gallium crystal (henceforth the term “crystal radio”)  about a year later. Larger versions of his “valve” would later become rectifier tubes used to convert AC to DC.

Lee De Forest obtained a Ph.D from the Sheffield School of Science at Yale University. His dissertation was on the subject of radio waves. Despite his degree, he remained more of an intuitive inventor like Thomas Edison, than an academic theorist. Upon inventing the vacuum tube as we now know it, he was quoted as saying he “didn't know why it worked, it just did.”

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Vintage Radio
12:49 pm
Mon October 7, 2013

That's a Radio?

Early 1920s kit or home made radio.
Credit Paul Litwinovich

The average person probably wouldn't know what this object was if they came upon it at an estate sale or in an antique shop. They would have less of a clue were it not displayed with the headphones, which are also from the same time period. The two largest knobs are graduated with a scale that reads 0 to 100, the others are not labeled at all. If you were to turn it around, you would see the first clue that it might be a receiver of some type. There are seven thumb screw terminals, two of which are labeled antenna and ground. Three are labeled "B Battery", and the remaining two are labeled “A battery” and "Common". There is nothing to indicate what frequency it receives, such as 540 –1600, or whether it is AM or FM.

To a collector of vintage electronics, this item would definitely warrant a closer inspection. Since this is the first of my articles on vintage radio, I decided to go way back to the beginnings of radio as we know it today, the early beginnings of the vacuum tube era. This radio is a very early set, built with parts which appeared on the scene between 1919 and 1922. It may have been a kit radio, or it may have been designed  and built by a hobbyist from plans found in an early wireless magazine. Perhaps it was built to monitor the broadcasts of the first licensed broadcast station KDKA which hailed from Pittsburg PA in 1920. It may have been built to allow its creator to monitor wireless telegraph transmissions between ships and shore stations, or for use by an early amateur radio operator.

There were receivers which predated the age of tubes. An Englishman named John Preece began wireless transmission of Morse code for commercial purposes  as early as 1892, and Marconi made his famous transatlantic transmission on December 12, 1901, but I’ll cover those technologies at a later date.

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