HISTORY OF STATION WLW's 500kW TRANSMITTER PART I Dick Reiman, Historian At the December IEEE meeting, Edwin Dooley and Clyde G. Haehnle presented the "History of Station WLW's 500kW Transmitter." The following is a review of the presentation based on their notes of the meeting. Powell Crosley, Jr. was a pioneer in the new field of radio broadcasting in 1920. He wanted to become the Henry Ford of radio manufacturing, and the radio broadcasting was a means to popularize the new medium. His business philosophy was to market the lowest priced radio possible to reach the market of people with modest incomes. If the broadcast channel was of higher power level, a simpler radio could be produced for this market. His interest in radio began in his youth, when he asked for a radio from his father. Instead of a radio his father bought him a book on how to make a radio; thus began his radio career. In July 1921, he began broadcasting from Station 8CR using a 50 watt transmitter at his home on Davey Avenue in College Hill. His first program was a record of "Little India." He requested listeners to send him a card if the received the broadcast, and several did. This was all the encouragement he needed. In March 1922, the transmitter power was increased to 500 watts, and Crosley was granted a license to use WLW call letters. He was assigned two frequencies, 833 kc for entertainment programs, and 619 kc for weather and farm reports. In January 1925, the power was raised to 5kW and on July 1, 1927 the frequency became 700kc. On May 25, 1928, Crosley was authorized to broadcast at 50kW. His production of radios proceeded in parallel with his broadcasting progress. He incorporated the mass production techniques of Henry Ford to build the most economical receiver. He found that women were the best workers because of their manual dexterity. In the 1930's, Powell Crosley began planning for a 500kW transmitter, the first of its kind. He contacted RCA Victor of Camden, New Jersey to build the transmitters. General Electric and Westinghouse became subcontractors to build the necessary components, from antennas to cooling systems. The new 500kW transmitter began broadcasting on April 17, 1934. In the next issue, the story will continue and some broadcast experiences related. HISTORY OF STATION WLW's 500kW TRANSMITTER PART II Dick Reiman, Historian At the December IEEE meeting, Edwin Dooley and Clyde G. Haehnle presented the "History of Station WLW's 500kW Transmitter." The following is a conclusion to that presentation. Powell Crosley, Jr. had acquired Station WSAI which provided a site for the 500kW transmitter on property in Mason, Ohio. The design and construction began January 1933, and receipt of the equipment and erection of the 831 foot cantilever guyed tower occurred in the summer. Testing of the broadcast facilities was done in December between 1:00 AM and 5:00 AM. The first broadcast was on April 17th, 1934 and continued until March 1st, 1939 when a bill passed in Congress limiting the power of commercial U. S. broadcasts to 50kW. The battle had begun over the use of the clear channel band, such as WLW's 700kc. Was it to be used with a more powerful 500kW signal, or by several stations with the smaller 50kW? At issue also was reaching the many rural areas beyond the range of the 50kW signal. The issue was finally settled by advancing technology when television and FM broadcast became a major factor, and the long quest for high power AM radio ended. Some of the technical features were as follows: *The RF amplifier consisted of three separate amplifiers driven in parallel with outputs in series, each could be isolated, and each had four type 862 triodes rated at 100kW plate dissipation, operated in a push-pull parallel class C mode. *The high voltage rectifier was 3-phase full-wave using six 870 ampere mercury arc tubes. *DC generators supplied 3,000 amperes of filament power to the tubes. The tubes were cooled by a half- mile long network of 1-1/2 inch Pyrex pipe with distilled water flowing at 660 gpm, powered by 50 hp pumps. *The boost from 50 to 500kW was done by the addition of amplifiers to the existing 50kW transmitter, a simple brute-force method without complicated controls. The operation had to deal with many lightning strikes to a metal ball on top of a pole at the very top of the transmitter. These were measured at 200,000 amperes. The signal strength was so great in the Mason area that crews from the project would respond the local complaints, such as arcing between two pieces of metal which crossed each other but were not securely bonded. Rain pipes of the correct configuration would tune in the signal. After all, the signal could be heard from coast to coast, so it had to be strong locally. In 1939 the FCC ruling limiting output to 50kW ended the commercial use of the 500kW transmitter. It was, however, kept in service under the call letters W8XO from 1939 to 1943, as stand-by emergency service in the event of a national emergency during this wartime period.