A team of great folks from the Federal Communications Commission (FCC)
office in Miami and the Federal Aviation Administration (FAA) in
Atlanta, Georgia and Fort Lauderdale, Florida visited us today. They
have been working with our engineers to solve some mysterious
interference that airline pilots have been reporting as they fly over
the east coast of Florida just east of our transmitter site in
Okeechobee. It turns out that our frequency of 7780 kHz on a 44-degree
beam up the East Coast of North America and on to Europe was radiating a
low-power 17th harmonic (17 times the nominal frequency of 7780 kHz) on
a frequency used by aircraft flying in the area. After a lot of hard
work by everyone, we have come up with a plan to switch our frequency of
7780 towards Europe to 7730 kHz as of the beginning of the next
shortwave broadcast season (the A22 season) on March 27th. And we will
switch our transmission to Mexico and Southwestern North America from
7730 to 7780 kHz. After doing a series of tests today, we think that
will solve the harmonic interference problem. Thanks to everyone for
their assistance. It's much-appreciated.
http://www.hard-core-dx.com/article.php?story=20220228201501688