TopBand: Re: 160 LP (fwd)

Earl W Cunningham
Thu, 04 Feb 1999 21:42:36 EST

Bob, NM7M wrote:
"I hate to be a "party pooper" but I really doubt you worked that A45 via
160 meter long-path at 1406 UTC.

"I looked up your QTH (Tucson, AZ) and then put the path in the mapping
utility of MINIPROP PLUS.  I find that more than half of the path, going
into the southern hemisphere, was in sunlit regions.  160 meter RF just
cannot survive under those conditions, summer in the southern hemisphere.

"On the other hand, the short-path to A4 was all in winter darkness in
the northern hemisphere.

"Ionospheric absorption being the limiting factor that it is on 160, I
can only conclude it was a short-path QSO and your SX Beverage was
playing tricks on you.  It is not the first time that sort of thing has
I looked up both N7DD's and A45XR's coordinates and used DBGRID to
calculate the beam headings to/from both QTHs.  Disregarding any skew the
signals might have taken, long path from N7DD to A45XR is at a bearing of
191.37 degrees, or 11.37 degrees west of south.  For A45XR to N7DD, the
LP bearing is 169.51 degrees, or 10.49 degrees east of south.

I then set up GEOCLK at the exact time/date of the QSO to get an idea of
what the terminator looked like.  Propagation could've occurred on either
short path or long path, following the "gray line" either way.  Based on
Larry's use of his SW Beverage to hear A45XR, there's no doubt in my mind
that the QSO was via long path. If the LP beam headings were more to the
south, then we run into the daylight problems that Bob suggests.

73, de Earl, K6SE

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