Message-ID: <003201c30f4f$ee182a60$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <000c01c30f29$700bc080$bbe4fc3e@l8p8y6>
Date: Wed, 30 Apr 2003 20:36:42 +0100
MIME-Version: 1.0
Subject: LF: Re: strange condx
Content-Type: text/plain; charset=iso-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Sender: <owner-rsgb_lf_group@blacksheep.org>
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

Hi Mal, thanks for the interesting report. I have looked at the darkness
shadow at that time using Geoclock, and it crosses the path at quite an
angle, approximately between Berlin and Helsinki. That means the ionosphere
is probably still illuminated at around the Russian boarder.  My guess is
that the early signal was a one hop path from the bottom of the E-layer at
about 100kms altitude. Later higher order paths become possible as your end
of the path goes into darkness and these destructively interfere giving very
deep sharp fades. It is surprising under present conditions that the initial
signal was so strong as it is a "long hop". Two hop signals would normally
be stronger and more stable over that distance except that there is a lot of
nightime absorption due to the after-effects of the geomagnetic activity.
This would weaken the two hop signals. Maybe that makes them of similar
strength to the one hop and hence the deep fade (cancellation when the
phases oppose)

Of course I could just be totally wrong....but it sounds like a good story.

Cheers de Alan G3NYK
alan.melia@btinternet.com

----- Original Message -----
From: "hamilton mal" <g3kev.ham@virgin.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: 30 April 2003 16:01
Subject: LF: strange condx


Yesterday early evening around 1900 z RN6BN was a very strong signal,
stronger than usual about S6 then about one hour later he suddenly started
to disappear, this is when I worked him on 137.7 QRS3, we have worked
before. Although weaker he was solid O copy and he gave me the same report.
Shortly after we worked he disappeared totally on a CQ then re appeared,
perfectly readable but during the evening never got as strong as around
1900z. I have not noticed this rapid QSB on signals before on 136 khz There
seemed to be some unusual propogation at this time.
YU7AR and OK1DTN were very strong with some variations on their signals also
during the evening.
I also observed some DL acty and DK8KM on hellscriber or some variation of
the mode, solid signal.
73 de Mal/G3KEV