RealAudio File


The following is a RealAudio file (59-kb) than runs for apx 30 seconds.
Many thanks for the assistance of N5JEH in creating it.

KSFY-13

     The recording is of 215.76 MHz Es (US TV Ch A-13 FM audio)
                     Sioux Falls, South Dakota (EN13RM)
       made on Feb 7, 1977 at 1800 CST (hence the news lead-in).

As this was 978 miles, the Secant Law gives a 1400-mi MUF of well into
the then 220-MHz band.  Unfortunately, besides my lacking even 144-MHz
gear back then, the endpoints from EL09 would likely have been into the
very underpopulated areas of ND or VE4 (see the graphic below). 
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At my 1983 Central States VHF Society Convention presentation I was
asked about how often 220-MHz Es would occur.  I gave the somewhat
offhand number of once in 10 years.  Jun 14, 1987 provided the first
two-way Es QSO on the band - between the Dallas, TX area (K5UGM) and
Jacksonville, FL (W5HUQ).  The next reported (partial QSO) occurrence
seems to have been this past summer - so my once-a-decade guess would
so far appear to be fairly accurate!
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[Map of Ch 13 Es path Feb 07, 1977]
Software by K9SE (K0BI)

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Page last modified: November 27, 1997
minor mod: January 27, 2001
correction: June 14, 2014