Re: Satellite reception problems


"Jeff Layman" <jmlayman@xxxxxxxxxxxxxxx> wrote in message
news:gtce3h$mma$1@xxxxxxxxxxxxxxxxxxxx
After setting up reception on Astra 2 ok earlier in the year, leaf
appearance has badly affected reception here in West Sussex (I thought it
might...) . The beam arrives effectively in the "V" created by the crowns
of a couple of partially overlapping trees. One of these is a damn great
sycamore - already around 25 m high - but with a lot more growth left in
it. That is the one causing the problem.

But why has it affected horizontal polarisation reception much more than
vertical? I've checked the LNB and that hadn't moved. But just in case I
loosened and rotated it clockwise and anticlockwise in several positions.
No difference in the non-existent H reception, but eventually lost V too,
so put it back where it was. Minor adjustment of the dish resulted only
in losing the V reception as well as the H.

Options are limited. At present the dish (65 cm) is on the bottom end of
a 1.5" 16g galvanised steel pole between a 24" K and T bracket, just below
the gutter line. The T is at the extreme bottom of the 3m pole, with the
K about 50 cm above it. At the top of the pole is an 18-element group A
yagi (Crystal Palace), and about 50 cm below that is a 15-element group E
yagi (Midhurst). I suppose I could move the dish up about 1.5 m to just
below the Midhurst aerial, but would it interfere with it? Also, with the
dish now well above the gutter, and much more exposed to the wind, the
pole would be taking much more strain. As would the T and K mounts, which
seem to be fixed with a 5 x 12mm AF hex-headed screws into some sort of
plastic plug fixing. I suppose I could get another mount and move the
dish back, but I can't add more than a couple of meters, and that
translates to only 1 metre in gained height at the tree. Also, that would
only work in the same line-of-sight - moving it back along the same wall
would only change the beam direction to right through the main part of the
tree crown! And it would probably only gain a couple of years' viewing
before the tree obscured that signal too.

Any suggestions other than a chainsaw?

Really you need to experiment with a minidish and a meter. Try various
locations and you should be able to build up a mental picture of the shadow
zone. This takes some patience. It's really a matter of finding places where
there's no signal, then linking them in your mind and relating them to the
visible obstructions.

Don't put a 65cm dish above the top bracket if the mast is as described. Use
a pair of tripod brackets and an aluminium or steel scaffold tube.

If this is for 28E I would be inclined to mount a minidish high up rather
than a 65cm lower down. You can put a minidish 3 or 4m above the top
bracket.

Bill



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