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REVIEW
FIVE EASY PIECES --
SATELLITE DISHES
Space technology comes down to earth with a bump this month
as we investigate five very different satellite ‘dishes’....
GRUNDIG GREGORIAN £430
Now this one really does
look like a proper satellite dish and not an anaemic wok. The Gregorian layout
employs two dishes, the incoming signal is focused by the 90cm offset dish onto
a small secondary reflector, which further concentrates the signal onto the
LNB. It’s a highly efficient design, though the jury is still out on whether
the additional cost and complexity of this design is better than, say, a larger
dish or more efficient LNB. The price looks steep but this is a fine example of
Norweigan precision engineering, and it’s built to last. It comes complete with
a low noise (1.0dB), dual-band LNB that covers pretty well all of the frequency
bands used by the majority of TV satellites. What’s more it includes a
motorised polar mount and can track across the whole of the ‘Clarke Belt’; with
the right receiver, positioner, decoders and a clear view of the Southern sky
this dish is capable of picking up several hundred TV channels!
This is not the sort of
dish you would use just to watch Astra channels, it’s designed for those who
want to explore wider horizons, but haven’t necessarily got the space for a
mini Jodderel Bank in their back yard. Performance checks on Astra were pretty
meaningless, it worked exceptionally well, however, it really showed its mettle
on the lower-power satellites, and in particular the more exotic ones further
down towards the Western and Eastern horizons which carry news feeds and
unscheduled programming, where it
compared well with a 1.2 metre reference dish.
Value 90%
Grundig 0788) 577155
LENSON HEATH 35cm £100 (with LNB and suction mount)
It looks far too small to
be any use but this compact 35cm dish works surprisingly well, though only
throughout the South of England. It’s intended mainly for portable
applications, on caravans or boats (in very calm water) but there’s no reason
why it shouldn’t be used for household installations in areas of good signal
strength. The dish itself is an offset parabolic design, made from aluminum, so
it’s very light. It comes with a comprehensive mounting kit for a fixed installation
though some companies, notably Polecat, sell it with an LNB and suction cup
mount, which can fix the dish to any smooth surface (car or caravan body, or
window for example).
The dish mount is fairly
easy to put together and align, though you will need a couple of spanners, and
a compass if you’re using it on the road. It has a fairly narrow field of view,
so it’s worth taking a few minutes to get a good picture but once locked off
the mounting bracket is very rigid and won’t shift, even if it is knocked.
The dish can be brought
without an LNB, but it makes sense to use a high-performance, low-noise design.
We tried ours with a Protel 0.8dB and picture quality was good with
sparklie-free reception across most Astra channels. UK Gold was a bit noisy, as
usual, and our receiver temporarily lost lock on encrypted channels a couple of
times, when the sky was heavily overcast, otherwise picture and sound quality
was quite satisfactory, and we suspect it would be almost indistinguishable
from a standard 60cm dish at locations along the South coast.
Value 75%
Polecat (0222) 770548
METAL DUSTBIN LID Around £17
Yes, it really does work! A
dustbin lid may not be a perfect parabolic reflector but it does the job well
enough and we were able to get quite passable pictures from the Astra
satellites at our South London test site. The dish took around half an hour to
build using materials that came to £17; it would have been a lot cheaper but we
couldn’t find anyone who would sell us a dustbin lid on its own... The bin with
it’s 50cm diameter lid cost £13.99 from a high-street hardware store, the LNB
arm is made from a 25cm length of threated steel rod, brought from Sainsbury’s
Homebase for a pound, the LNB support bracket came from a local satellite
installer and cost £1.50, and the mounting bracket was a large Jubilee clip,
another 85 pence. You’ve got to add on the cost of the LNB, we used a fairly
ordinary Marconi Solo, we’ve seen them selling for around £35; the mount need
cost nothing, our dish worked quite happily clamped to a cast iron drainpipe.
Alignment took only a few
minutes, it involved quite a bit of trial and error to determine the optimum
length for the LNB arm (mainly by waving the LNB around in front of the lid
until we got a picture). It wasn’t all guesswork, though, we used a compass to
get a bearing on the satellite (19.2 degrees East of South), and the receiver
was pre-tuned to a known channel.
Of course we’re not
suggesting that it’s a substitue for a proper dish, we wouldn’t fancy its chances
in a high wind, and it would probably be hopeless North of Watford, you would
need a much bigger dustbin for that... Hopefully it demonstrates that the
technology isn’t as scary as it looks, and satellite dish design isn’t
necessarily as complicated as some would have us believe.
Value 80%
Shop around...
REVOX HORN ANTENNA £130
Almost but not quite as
rare as a BSB Squarial, the Revox horn antenna was briefly famous about three
years ago. It looked like the answer to a lot of closet STV viewers prayers, it didn’t look anything
like a satellite dish and could be tucked away beneath the eaves, without
attracting too much attention. The horn design is a scaled down version of
industrial and military microwave antennas, but it didn’t translate terribly well
to domestic satellite applications. Apart from being very expensive the biggest
problem was a wider than normal field of view and early models had a nasty
habit of picking up signals from adjacent satellites. This problem was largely
cured but the reputation for poor performance stuck and it quickly went out of
favour. Another drawback is that it is deceptively heavy; installers hated it
because the alignment could be difficult and it would often droop or sag on its
mounting.
Nevertheless, later
examples work reasonably well and there’s are still a few of them about in
dealers stock rooms up and down the country. We did a little phoning around and
found several for sale, ranging from £100 to around £150, though most of the dealers
we spoke to said they were open to reasonable offers... Installation can be
tricky but on suitable sites, where it can be ground mounted it is reasonably
simple to align. Picture quality on our sample -- one of the later models -- is a little below what you might
expect from a standard 60cm dish, there are some sparklies on UK Gold, but on
the whole it is acceptable, and it still doesn’t look anything like a satellite
dish!.
Value 70%
Enterprise Satellite (0932) 820302
TECHNICSAT SATENNE Typically £90
Remember the ill-fated BSB
‘Squarial’? Well, now you can re-live those memories with the Technisat Satenne
flat-plate satellite antenna. It works in a similar manner to the squarial,
except that it’s designed to pick up transmissions broadcast by the Astra
satellites. Inside the plastic cover there are rows of conductive strips, each
one a tiny antenna, which picks up the satellite signals and routes them to an
LNB mounted inside the back panel of the antenna. It measures just 50cm across
and it looks quite discreet, so it’s worth thinking about if you don’t want the
world and his wife to know you watch satellite TV. The trade-off is efficiency,
in short it doesn’t work as well as a comparably sized dish, though that
needn’t be a problem South of Birmingham, say, where the Astra signal remains
relatively strong.
Installation and alignment
are very straightforward. It comes with a standard-sized alloy bracket which
will clamp to most types of wall mount. The antenna plate has a slightly wider
field of view than a parabolic dish, so care needs to be taken to avoid picking
up signals from adjacent satellites, and this can be quite tricky. Picture
quality is reasonably good, though the reduced sensitivity shows up on weaker
channels, like UK Gold where there’s always a few sparklies in the picture.
They start to appear on other channels during bad weather and the picture may
become quite poor in a really heavy downpour. It’s not much good picking up for
other TV satellites either, most of which broadcast weaker signals than Astra. In
its favour it is quite reasonably priced, and it doesn’t stick out like a sore
thumb.
Value 80%
Technisat (0902) 791525
CONCLUSION
DISH Price Rating
Grundig Gregorian £430
(inc LNB & motor) 90%
Lenson Heath 35cm £100
(inc LNB & mount) 75%
Metal dustbin lid £17
(ex LNB) 80%
Revox Horn Antenna £130
(inc LNB) 70%
Technisat Satenne £90
(inc LNB) 80%
WHO’ S BETTER, WHO’S BEST
Best picture quality Grundig
Easiest to assemble Lenson
Heath
Easiest to align Grundig
Lease offensive to look at Revox
& Technisat
Best value for money none
of the above, get an ordinary dish....
MINI GLOSSARY
CLARKE BELT -- (see also Geosynchronous) ring of satellites
orbiting the earth. Named after sci-fi writer Arthur C Clarke who thought up the idea back in 1945
GEOSYNCHRONOUS -- (also geostationary), a satellite which
orbits the earth 36,000 km above the equator, at a speed of 11,069 km/hr will
appear to remain at a fixed point in the sky when viewed from the earth
LNB -- low noise block converter, device which converts
microwave signals from satellite to lower, more manageable frequency
OFFSET PARABOLIC -- parabolic dish shaped so that the focal
point is below the face of the dish, this eliminates any ‘shadow’ from the LNB
and its mounting arm, which would reduce the dish’s effective surface area
POLAR MOUNT -- carefully configured mechanical bearing that
enables a dish to track along the curved satellite belt
SPARKLIES -- bright flashes on an STV picture, caused by
random noise picked up by the dish or generated by the receiver electronics,
indicative of a weak signal
---end---
1994 0809
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