Message-ID: <015a01bf20d8$754bf440$af12063e@default>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: "rsgb_lf_group" <rsgb_lf_group@blacksheep.org>
Subject: LF: re Dave's corrections to my 'Musings' on CFH
Date: Wed, 27 Oct 1999 21:46:30 +0100
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Hi Dave, thanks for the check...the trouble with postage stamp calculations
is you can't read your own writing afterwards! Not when your eyesight is
like mine.

I did get the distances screwed up. I thought the nearest path to the 'New
World' was under 2000 miles (i.e just over 3000km) but that is from Mallin
Head to Gander Newfoundland rather than Nova Scotia. Distinctly duff
geography on my part, and its another 800kms to Halifax.  My locator program
gives my location to CFH as 4700kms. I must admit I began to have quarms
about the distance calculation, and dug out my old great circle map to check
it. Healthy skepticism for other people's software! The interesting thing is
its makes an almost insignificant difference to the path attenuation.
Richard Lamont's Graph shows the water path attenuation rising at 20dB per
decade( of distance) so the attenuation for 4500kms (rather than the 3000 I
used ) is a mere 3dB more. This would seem to confirmed by some comments
from the Antipodes reporting very much greater distances heard across water.

The 200 foot quote was not a misread of Jon's data, I was using it as a
stepping stone to 600ft. I thought doubling a mast height (WA2XTZ has 100
foot masts I believe) might give 3dB 'gain' so multiply by 6 is around 8dB.
I expected someone to leap on my logic and beat me up here.... it was a kind
of a 'kite flying' exercise to see if anyone could come up with a better
figure.

 There's no doubt it going to be a tough one, Dave....like Top Band in the
early days with 10w DC....but that proved 'do-able' in the end. The one
interesting effect, suggested by someones anecdotes of old ROs,  was that
the path may not be reciprocal.

Whoops, I've done it again, and flooded the reflector with messages....well
hope you found them fun I certainly did.

73 de Alan G3NYK
Alan.Melia@btinternet.com