TWO INTO ONE DOES GO...

INTRO

If thirty or so satellite channels simply aren't enough then here's a simple, and relatively inexpensive way of expanding your horizons

COPY

It used to be so simple; if you just wanted to watch the Astra channels you chose a 60 or 80cm fixed dish system. Those with larger appetites installed extra dishes or multi-satellite systems, with motorised dishes. Now there's a third alternative, LNB support arms that fit on to fixed Astra dishes. These allow a second LNB --  mounted on the arm -- to pick up signals from adjacent satellites, principally the two Eutelsats at 10 and 13 degrees East of South which broadcast upwards of twenty  TV channels across Europe. This rather elegant conjuring trick is made possible by the fact that an Astra dish has a comparatively wide field of view and signals from satellites close to the Astra birds (19.2 degrees East of South), are focused to points a few centimetres either side of the normal LNB, where they can be picked up by the second LNB.

There's no such thing as a free lunch so what are the drawbacks? First and foremost is picture quality; to get a halfway decent picture from the Eutelsat satellites you need at a dish at least 80cm across, pointed in their direction, it also helps to live South of Watford. A 60cm dish with a second LNB, even under ideal conditions and with a high-performance LNB, is going to produce a noisy picture. One way of  minimising losses is to re-direct the dish at Eutelsat, using the second LNB to pick up the more powerful Astra signals. The other problem is fitting the arm or extender; if you've installed your own dish or it is readily accessible it shouldn't prove too difficult but if you baulk at the prospect of fiddling around with small bits and bobs twenty feet up a ladder, and running an extra cable to your STV tuner then leave it to the professionals.

We've been looking at two of the dozen or so LNB arms/brackets on the market, to see how easy they are to fit, and more importantly, how well they work. Don't forget that you need to add the cost of a second LNB to the prices we quote, plus any installation charges; also bear in mind that very few STV receivers have provision for a second LNB, so connection may involve buying an LNB switch box, or a good deal of plugging and unplugging the various leads, when you change from one satellite to another.

LITTLE WIZARD £18.50

This is the simplest and cheapest of the two devices, and it is configured for the closest Eutelsat at 13 degrees. It's made entirely of plastic and will fit most popular dishes and LNBs. The design is very straightforward, easy to fit -- fifteen to twenty minutes, with the wind in the right direction -- and it allows for the dish to be focused on Eutelsat F1, with the second LNB zeroed in on Astra. This is our preferred method, and it certainly helps with picture quality. On our test rig (80cm Lenson Heath mesh and Marconi 'blue caps', 1.2dB) most F1 channels were noisy but quite watchable. We also tried it with a 60cm mesh dish and after a good deal of fiddling about we managed to get both picture and sound, which was just about viewable, though it would probably tax even the most ardent enthusiast after a few minutes. Substituting a lower noise (1.0db) Swedish Microwave LNB brought the picture back up to somewhere near to just acceptable.

PRO ARM £

Pro-Arm is an altogether more substantial affair, made entirely from metal (apart from the LNB clamp) and  it is designed to fit the square-section boom on Lenson Heath type dishes; two sizes are available, to suit the slightly different solid and mesh style dishes. Pro-Arm is even easier to fit (compared with Little Wizard), as there's only three bolts -- with self-locking nuts, and because the original LNB is undisturbed final alignment is that much easier. The LNB clamp is less flexible than Little Wizard and reducing or packing rings will be necessary if its used with LNBs that have throats narrower than 40mm. The slightly wider angle of adjustment means it's also just capable of 'seeing' Eutelsat F2 at 10 degrees, though in practice it would be necessary to use a 1-metre dish, or larger, to get any sort of picture. With the 80cm mesh dish pointed at Eutelsat F1 and using the Marconi LNB on-screen performance was comparable with the Little Wizard , though getting a good picture involved considerably less mucking around with the various adjustments. Going back to the 60cm dish there was no improvement, though again the adjustments were far less fussy.

THE BOTTOM LINE

Pro-Arm would be our first choice for use on a Lenson Heath type dish, Little Wizard has much to commend it, not least the price but it can be quite fiddly to set up.

---end---

R.Maybury 1993 0705