VINTAGE RADIO

Order Out Of Chaos

While perusing the shopping mall this past 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 one of those vintage sets featured in my November and December 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 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. The Titanic also played a role in this legislation. The new rules included a requirment 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 ones being a Frank Conrad who began playing music over his amateur radio station 8XK from a garage in Pittsburgh 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.

The first broadcast license was issued to Westinghouse for their station KDKA in Pittsburgh, PA. Frank Conrad was now working for Westinghouse as assistant chief engineer. On November 2nd, 1920, KDKA went on the air. Its first broadcast being coverage of the Harding/ Cox presidential election. Despite Mr. Conrad’s first foray into the world of “commercial broadcasting” with his records for promo trade, advertising was not the driving force in early radio. Radio manufacturers were building stations to encourage people to buy their radios. In fact, direct advertising was prohibited by DOC regulations. A few stations skirted the law by doing “trade ads” similar to what Mr. Conrad had done as an amateur. Some were cited or given cease and desist orders by the DOC for selling airtime. The commercial restriction was dropped in 1923. By now a reasonable order had been established and the broadcast industry began to grow. Broadcasting was regulated by the DOC until 1927 when an act of congress created the Federal Radio Commission. The DOC continued to regulate other radio communications until congress enacted the Communications Act of 1934, creating the Federal Communications Commission (FCC) and placing all forms of radio communication under its jurisdiction.


Radio of The Month
Radiola 18 This month’s radio is a 1927 RCA Radiola 18. It features an oak cabinet with a hinged top, gold leaf border and a large brass escutcheon with a lighted dial. The style would become known as a “long box” for obvious reasons. Displayed with the Radiola is an RCA Model 100-A paper cone speaker.

The radio was very state of the art, incorporating almost all of the design improvements that the industry introduced in 1927. These included the use of two new types of tubes, a ganged single knob tuner (no more triple tuning knobs), enough power to drive a large paper cone speaker, and most important, AC operation, no more cumbersome batteries! It still required an outdoor long wire antenna but otherwise was as easy to operate as a modern radio. The only controls were the on-off switch, volume control, and the tuning knob. The Radiola 18 still used a simple 0-100 scale for a dial.

Radiola 18 Dial

The circuit utilized the still popular three stage TRF circuit, but it was nice to have all of the stages tuned by just one knob. RCA was determined to take its place as a titan of the radio industry and competition was fierce. Radios were judged by how many stations they could receive. Other major players such the Grigsby-Grunow company were building sets with up to six TRF stages. RCA realized that greater profit could be made by building a three stage radio if they could make it perform as well, or better, than the competition. The RCA engineers had a clever idea. They would add a small amount of regenerative feedback to the second TRF stage. I discussed the very early regenerative receiver circuit in the November 2004 edition and how regeneration greatly improved the gain of a tube. The regeneration was kept to a low level so as not to create the instability that the older sets suffered from. This was considered such a trade secret that the added components were not shown on the schematic and no patent was applied for. The regenerative feedback adjustment was mounted on the bottom of the chassis and hidden by the model and serial number label. RCA required that all radios requiring warranty service be returned to the factory as no information regarding the use, adjustment or even the existence of the control was initially released. The circuit did work well giving the Radiola 18 and subsequent models a competitive edge for two or three years. Click here to view schematic

Two new tubes were introduced, both for the purpose of allowing the radio to be operated on AC power instead of batteries. The type 227 triode, used as a detector, featured an indirectly heated cathode. Prior to this, all tubes had directly heated cathodes and if used with AC power in a detector circuit would result in a loud hum in the speaker. The other new tube was the type 280 power rectifier which allowed AC to be converted to DC as was required by the radio circuits themselves. The use of AC here would also result in a hum.

Inside the Radiola 18 If we look inside the Radiola 18 we see two separate chassis. The radio chassis has six tubes, and yes, they are on and glowing! Three are for TRF circuit, one serves as a detector and two are audio amplifiers. The power supply with its rectifier tube is the smaller chassis on the right. This was done for more than one reason. Much of rural America was not yet electrified. The radio could be purchased without the AC power supply and used with batteries. Much of Europe used 220 volts instead of 120 volts, so more than one type of AC power supply was offered. The three section gold plated tuning capacitor is clearly visible. This particular radio is completely original except for the power cord which was replaced because it had frayed. No chassis or cabinet restoration has been done. It is still fully operational and is a real performer when hooked to a good antenna, not bad for a 72 year old set.
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