Topband: K5K logs

[Robert Brown]

                     A Review of the K5K Logs
 
     The recent K5K DXpedition to Kingman Reef provides additonal
insights to propagation on 160 meters.  The present brief note is
a summary of those features.
 
     For the period October 23-29, geomagnetic activity was of a
minor nature, the Ap index ranging from a low of 9 on October 27
to a high of 32 on October 29.  That level of activity was enough
to hinder any sort of propagation across the northern polar cap
into Europe.  By way of interpretation, low level auroral activity
and polar drizzle were probably sufficient to fill up the usual
night-time electron density valley above the E-region and block
the possibility of any signal ducting across the northern polar
cap.
 
     As a result, DX contacts were generally limited to distances
out to 10,000 km from the operating location.  The two exceptions
to this were contacts with ZS4TX and LU7XP, 17,500 and 16,800 km,
and those contacts were realized during quiet magnetic conditions,
Kp of 1 and 2, respectively.
 
     The general pattern of DX contacts followed the location of
the dark hemisphere, east of Kingman Reef before local midnight
(1032 UTC) and west after midnight.  During the "Witching Hour",
60 minutes centered on midnight, contacts were made with QTHs
within the 10,000 km limit of the dark hemisphere centered on the
anti-solar point, such as VK6, JA, UA0, WL7, VE1, W1-W0 and P4.
At other times, DX contacts were out to distances of 10,000 km or
less - YV, YS, TI, VK and ZL - in spite of the region of darkness
extending to greater distances after sunset and before sunrise.
 
     The two long-haul DX contacts point to signal ducting beyond
the 10,000 km multi-hop limit discussed recently by K9LA.  That
limit follows from conventional ionospheric physics but the lack
of European contacts due to filling of the electron density valley
in the polar region is of magnetospheric origin.  Beyond that
sort of exception, the K5K logs show the daily variation of DX
contacts fall within those expected from locations in the oval of
darkness in azimuthal equidistant mapping.
 
     The assistance go Garry Shapiro, NI6T, was invaluable in
reviewing the K5K logs.
 
73,
 
Bob, NM7M
 


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