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.


     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). 
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!

[Map of Ch 13 Es path Feb 07, 1977]
Software by K9SE (K0BI)


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