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 Crosley?s Every Body?s 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
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Topband Reflector
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