Satgen 131    The 11 year DX cycle    by GM4IHJ        29th Sept 91
YOU ARE REQUESTED NOT TO ALTER BIDS ON THIS BULL IF YOU RETRANSMIT IT

With any luck the next 4 months should provide some of the best HF
satellite DX of the decade. RS12 is on Mode K 21MHz up 29MHz down and even
at the very begining of the winter DX season we are getting sub horizon
ionospheric propagation of RS12 uplink and downlink around the world, with
sat signals coming into UK from near the antipodes ( that point you reach
if you dig a 12756km deep hole in your back garden).

We are still close enough to the recent Solar Sunspot cycle peak for
RS12's 29.408MHz beacon to be announcing propagation from some exciting
places . This last week I heard RS12 over Antarctica at 79S 267W  ( at
1718ut) heading up towards Perth in VK6 and the signal was in and out for
nearly 28 minutes up to 50N 232W. Two days earlier RS12 was 536 from the
North Pacific at 46N 145W at 1234ut. Last season G3IOR used one of these
South to North runs, up the Pacific, to QSO ZL for the first G/ZL sat
contact ever. G is normally unable to hear near antipodeal ZL via any sat.

So what are the secrets of operating this mode, apart from the fact that
this DX usually occurs when RS12 IS NOT ABOVE YOUR HORIZON. First your
reception must be good, signals are usually weak , can be broken up ,and
often have a poor tone.  Second you must be able to ignore the terrestrial
21MHz users who inadvertently access RS12 and transpond to 29MHz. IHJ Rx
antennas are sloped selectable 10m dipoles with preamps on the dipoles and
a second receiver tracks the 29MHz search 8.204 MHz approx lower ( on the
21MHz band) to identify the terrestrial 21MHz users if possible. Try to
make your CW as rhythmic as possible . G3IOR was easy copy yesterday as he
had a QSO , but the man at the other end had an arhythmic fist I could not
read. Most of all do not imitate X , who forgot IT WAS HIS CALL I NEEDED
TO GET, as he sent GM4IHJ GM4IHJ GM4IHJ GM4IHJ de Blurp bleep.

For a last major clue to this DX ,please remember that RS12 is way above
the ionosphere. When it passes near your station in daylight it sounds
awful because it has to struggle to get down through the ionosphere at
all, and almost no 21MHz gets up to it. By contrast when RS12 is on the
night side of the terminator line but within 4000kms approx of the
daylight ionosphere, its signal can easily penetrate down through a thin
ionosphere and may then chordal hop to the underside of the dense daylight
ionosphere and propagate via the underside of that ionosphere to you.
Equally with luck your 21MHz can propagate back on the underside until it
too reaches the terminator and can penetrate upwards to the satellite. For
further detailed examples see pages 90 to 94 of RSGB Space Radio Handbook

There is no reason why this situation should not work both ways Eg VK ZL
to UK ( 1000ut to 1300 appears best) sat near VK or ZL, OR the other way
around sat near UK at UK pre dawn say 0500ut thence propagated to VK ZL.
VK6 to/from Eastern USA may also be possible. 73 de GM4IHJ @ GB7SAN