Satgen 221   HF Satellite DX   by GM4IHJ                     19th June 93
BID of this msg is SGEN221  Please use this Bid if you retransmit the msg

The excellent Russian HF satellite RS12 has been operational on Mode K 
( 21.21 to 21.25 MHz up  and, 29.41 to 29.45 MHz down ) since 1991. But
listening to qso's on it and discussions about it, suggest that few users
understand it well enough , to make full use of its potential.

Operation is simple. 25 to 100 watts to a quarter wave vertical antenna
gets you a good signal into the transponder whenever the satellite is
above your horizon, as it can be every 100 minutes approx, up to 10 times
a day, with passes lasting about 16 minutes, to go from one horizon to the
other. The satellite downlink is received on any simple antenna connected
to a 29 MHz receiver, tuned roughly 8.2 MHz above the uplink. There is no
sideband inversion, so USB up gets you USB down. All Eastern USA is in
view of passes well to the west of UK and, Russian Asia and the Persian
Gulf are in range of passes going east of UK.

In addition to the above "Line of sight = Satellite above horizon
operation ", the 21 Mhz up to the satellite and the 29MHz down from it can
often reach the satellite when it is well below the UK horizon. This sub
horizon operation uses ionospheric propagation to bring the satellite
signal above your horizon from places as far away as Alaska or the Russian
Far East. The point to notice about this is, that when over Alaska the
satellite can see most of Western Canada above its horizon and provide
communication to that region provided the ionospheric link to UK is
present. Similarly when RS12 is over Siberia it can often see Japan and
has recently allowed sub horizon communication to Japan from UK, via RS.

In a typical recent example. RS12 far below the UK horizon at 1555 ut ,
was in range of Japan whilst sending signals to and from UK via the
ionosphere. Please note that if you ask your computer to table orbits of
this sort it may not do so. It may tell you " RS out of range". So you
need to check that your computer will give you tracking information even
when RS12 is well below your station horizon. 

This week 11th to 18th June 93 has featured 5 days out of 8 when RS12
orbits around 1800 ut approx were first heard in UK when near Japan , and
were still being heard in UK 14 or 15 minutes later when RS12 was over
Canada, giving excellent communications opportunities in Eastern Canada
and Northern USA from New York to North Dakota. 

So why not give RS12 a try. Get familiar with its "above the horizon
operation ". Then give its subtely different sub horizon capabilities a
whirl. 73 de GM4IHJ @ GB7SAN