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WSHU Chief Engineer Paul Litwinovich explores aspects of vintage radio, from the radio sets themselves to the people and technology that made it all possible.

Vintage Radio: The Contributions Of "Amateurs"- Giving Radio A Voice

Library of Congress Prints and Photographs Division

Last month we looked at Marconi and his pioneering work in the advancement of wireless communications. In the early days of radio, prior to government regulation, anyone with the knowledge could build a transmitter and go on the air. Even after the first attempts at regulation, one could still do this, the only rules being a mandate to yield to commercial traffic and to remain silent for a five minute period at the top of the hour to allow for distress traffic from ships at sea. In the days before what we now think of as "broadcasting," commercial traffic was considered to be the handling of messages between ship and shore stations, or between areas not connected with wires, such as overseas. Everyone else was considered an "amateur," even if they were a professor at a university, or an engineer trying to develop a new system. World War I brought further regulations prompted by the military, who realized the potential for this new form of communication. Eventually, licensing became the norm, with three types of licenses issued: commercial, for handling messages for hire, experimental, for research and development, and amateur, for others who wished to explore the art as a hobby or outside of what was specified by the other classes of licenses. Still, there were few limits as to what frequency to use or what one could transmit over the air.

Credit ARRL, used with permission
Clarence Tuska.

With the sinking of the Titanic in 1912, the U.S. Congress passed the Radio Act of 1912. In an attempt to reduce traffic that might interfere with distress signals, the act also limited amateur operations to "worthless" frequencies above 1500 kHz. Although this may have raised the ire of some at the time, it was probably the best thing that could have happened to both the amateur operators and radio in general. Amateurs began experimenting to discover what they could do with these frequencies. With increasing regulation and a ban on all amateur activities during WWI, amateurs realized that they had to organize to protect their interests. The roots of this organization were already in place when in 1914 Hiram Percy Maxim and Clarence Tuska founded the American Radio Relay League (ARRL). The distances that early radio technology could cover, particularly with lower power levels available to most amateurs, were relatively short, about 30 miles on average. The original purpose of the ARRL, as its name implies, was to form a network of amateurs who could relay messages across the country by repeating it from one to another. The league quickly grew in number, and within a year published its first monthly journal, QST, which is a Morse code term meaning that a bulletin is about to be sent for all amateurs. The ARRL also grew in lobbying power and influenced the development of radio regulations that included, and favored, amateur radio operators.

Credit Wikimedia
A small rotary spark gap transmitter such as an amateur operator would have used. Yes, the rotating gap might well be a saw blade.

From the beginning, almost all transmissions used Morse code, and, in part due to the robust nature of Morse transmissions, few commercial radio companies had any interest in exploring the technology of voice modulated radio signals. Prior to the invention of the vacuum tube in 1906, and even during its infancy, there were limited ways to create a high power radio signal. One way was to discharge large amounts of power across a rotating spark gap, which resembled something that one would expect to find in Frankenstein's lab. This resulted in a signal with a loud buzz, which actually made it easy for the listener to distinguish between the dots and dashes with the receivers of the day. It was, however, unsuitable to modulate with an audio signal. Smaller versions of spark gap transmitters were popular with amateur operators at that time.

The other way to generate a high power signal was to use a huge multi-pole alternator, spun at speeds high enough to generate a radio signal. These units were cumbersome and typically limited to frequencies less than 500 kHz, but were used by commercial companies, such as Marconi's, to generate up to 200,000 watts for overseas communications. The Morse code key switched the power to the exciter winding, the rotating electromagnet in the alternator, on and off. The output of such a system was, however, clean and quiet. Later attempts to modulate the exciter with audio produced poor results, as the bulky, spinning electromagnet responded poorly at audio frequencies.

Amateur operators however, were fascinated by the prospect of sending voice over radio waves. They started by building small homemade radio frequency alternators and inserting a carbon telephone microphone between the alternator and their antenna. This worked fairly well, but only for transmitters of a scant few watts. More than that would overheat and burn out the microphone.

Enter the vacuum tube. By the 1920, the vacuum tube had evolved to the point were it could be used to build transmitters of 100 watts or more, producing a clean signal that could easily be modulated by voice. Tubes also allowed the building of receivers that were sensitive enough to receive and demodulate a voice signal. The general population was fascinated by this new technology, and many built receiver apparatus. Some amateurs began broadcasting music over their stations, as this was not illegal at the time. One such operator, Frank Conrad, whose call sign was 8XK, began doing so in 1916. Radio listeners asked him for more. His efforts led to the first commercial station, Westinghouse's KDKA, going on the air in 1920, where he served as an engineer. The creation of broadcast regulations prohibited amateurs from playing music or other forms of broadcasting. From this point on, they were limited to experimentation and communicating with other amateurs.

After WWI, through experimentation, amateurs greatly contributed to the advance of the radio arts. One of their contributions was the development of voice modulated radio signals, which used Amplitude Modulation (AM), where by the strength of a radio signal is varied (modulated) by an audio component. They also contributed greatly to the study, and understanding, of how different frequencies behaved and how, at some of these frequencies, even weak signals could propagate over great distances. They soon demonstrated that those "worthless" frequencies above 1500 kHz weren't so worthless after all. By the mid 1920s, amateur operators were communicating across the Atlantic on shortwave frequencies using transmitters of 100 watts or less, while commercial companies were still pounding the lower frequencies with 200 kilowatt transmitters. For their efforts, amateurs were granted permanent privileges for frequencies in the 80, 40, 20, and 10 meter shortwave bands by international treaty in 1927. In modern times, these privileges extend all the way to microwave frequencies. The term "ham" was originally coined by commercial operators as a derogatory term to describe amateur radio operators. It caught on and was adopted by the amateurs as a favored nickname for those in the hobby.

Another area where these "ham operators" achieved commendable accomplishments is disaster communications. They became skilled at being able to put and keep a station on the air after a major disaster such as an earthquake or storm. In the early days this often included building a station out of scrap or junk box parts and attaching an antenna to just about anything, natural or manmade, that was still standing. If nothing was standing, kites and balloons were pressed into service to raise antennas. From the beginning of radio through present times, ham operators often facilitated the first communications in and out of a disaster zone.

The efforts of "mere amateurs” to prove that personal wireless communications were both doable and desirable led the FCC to create a “citizens band” or “CB” radio service in 1958*, wherein the average person could operate a two-way radio providing local (about a 15 mile range) communications with family or for small business use. CB radio reached a peak, if not an outright frenzy, of popularity in the late 1970s, forcing the FCC to increase the available number of CB channels from 23 to 40. Although the service is still available, and no longer requires a license to operate, its popularity waned with the invention of the cell phone as a means for the average person to stay connected to the rest of society.

* The FCC began experimenting with the concept of CB radio in 1945, just after WWII, using UHF radios in the 450-470 MHz band, but the radios proved too costly and complicated at the time for the average consumer. The service established in 1958 used inexpensive technology operating around 27 MHz.

Paul was a design engineer and engineering manager in the broadcast industry for14 years before coming to WSHU in 1990. He holds an FCC commercial radio license, and an extra class Amateur radio license.