I have been following the chatter on WLW and there are a few statements that are not correct. WLW at 700 KHz was a clear channel in North America ( US, Canada and Mexico) When WLW went to 500 KW in 1934, they created some international night time QRM by interfering with a station near Toronto on 690 KHz. The FCC pulled the permission for 500 KW operation at night until the Crosley engineers designed a directional antenna system to solve the problem. The criteria was to reduce the WLW nighttime 500 KW signal by 10 dB at Niagara Falls, NY. Fritz Leydorf did 20 different designs until he got the right solution. The engineers called the array Antenna #20. It consisted of two ¼ wave antennas across the road from the big Blaw Knox 5/8 wave stick. The antennas were on Crosleys Every Bodys Farm property. The two towers were fed with 600 Ohm open wire feeders and were phased by coupling some power from the main feedline.
This solution was used until WLW ceased 500 KW operation. Full time 500 KW operation stopped in 1939 but continued during the experimental time period (1AM to 6 AM) until 1943. In late 1943, the US Government wanted to borrow the 500 KW amplifier and send it to Australia for the war effort. The rig was partially disassembled when the plans changed. WLW never again used the 500 KW power but the rig was reassembled and in 1961, plans were made to convert it to 750 KW and an application was made for super power. There were about 10 other stations that also applied for super power. The plan was related to a military communications back up system using very narrow FSK for military data. The network was in place for many years during the cold war. The FCC quickly dismissed the applications and that was the end of the line for the concept of super power. There is a video on You Tube showing the 500KW rig at WLW. It is still in place but has been stripped of some of the heavy iron. The video was produced by Randy K7AGE. 73 Jay K8CJY 49+ years in Cincinnati broadcasting _________________ Topband Reflector
