HOME ENTERTAINMENT 94

 BootLog.co.uk

HomeSoftwareArchiveTop TipsGlossaryOther Stuff

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

 

[Home][Software][Archive][Top Tips][Glossary][Other Stuff]


Copyright (c) 2005 Rick Maybury Ltd.

admin@rickmaybury.com