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LF: Re: TransAtlantic II

To: [email protected]
Subject: LF: Re: TransAtlantic II
From: "Peter Dodd" <g3ld[email protected]>
Date: Wed, 12 Apr 2000 23:54:34 +0100
Reply-to: [email protected]
Sender: <[email protected]>
From Dave G3YMC
I wish Larry and the VE team all the best for their forthcoming
transatlantic tests - the choice of a period in November is excellent, and
if there is a chance then (and December) is the optimum time.
I think it would have given Peter Bobek a very special thrill if his aims
were met by a normal amateur using normal CW and an average station.
I don't recall that DJ8WL had any hang-ups about using QRSS - in fact
all my QSOs with him used this mode
Of the modes proposed for these Transatlantic tests the extremes are
30 or 40WPM CW and slow CW that would take several hours. From
experiance gained in the last couple of weeks in crossband tests on
72kHz/137kHz, mainly with I5TGC, I feel that the following notes may
be of some interest.
Even in good conditions a signal radiated from 1W erp is going to be
very weak by the time it has travelled 3000km, even on a sea path. In
periods of exceptional conditions such a signal may be audible but a
much greater chance of success can be had by using QRSS. This can
illustrated by a 72/137kHz cross-band I had with OH9UFO. Reino was
using nomal CW on 137kHz. I was a comfortable 'O' on QRSS. I was
asked to try fast CW and Reino copied his report and gave me 329 -
then lost it. This QSO was very marginal and if it wasn't for the
inital QRSS contact it would not have happened.
We have very little knowledge of the long distance propagation
mechanism of weak signals at LF. All we can say is (from observing
commercial stations) that they seem better in Winter at around
0400UTC for this path. The greater the distance the shorter the
openings so digging the signal out of the noise using very long
integration times is impractical.
The openings for the I5TGC experiments lasted half an hour, which
gave plenty of time for QRSS with a dot length of 3 or 4 seconds.
Exceptional conditions can occur any time so we should not confine
the tests to special expeditions. We should have a plan.

Regards, Peter, G3LDO

<[email protected]>

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