Fred M. Sloniker wrote:
About ten years ago, when I was living in Seattle, I had a clock radio
with rather crap reception, so finding a station I was both
interested in and capable of listening to when I woke up was a bit of
a task. One day, though, as I began slowly and carefully tuning the
dial to try to find something worth listening to, I stumbled across
clear, strong, and repeating Morse code. It wasn't an SOS, which was
about the only Morse I knew, but it was a good strong signal, better
than the alarm clock's built in buzzer, so I shrugged mentally and
left the tuner there. As a result, the pattern got burnt into my
brain.

Fred,

Upon re-reading your post, I note that you were living in Seattle at the
time. I think that clinches it.

The beacon you heard was at Boeing Field (hence the "BF"). It operates on
362 kHz (perhaps you heard the 2nd harmonic at 724 kHz). This is an "outer
marker" beacon and is named "Nolla."

See:
http://www.airnav.com/airport/BFI/ils/13R

Scroll down to "Outer Marker Informatio."

Also see:
http://www.mwenda.com/flyer.htm

Look under "other frequencies on the right.

Art Harris N2AH