[P1] Seeing the potential of an old dish.

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The only way to increase the chance of reliable reception from weak TV satellites is to increase the signal. A much bigger dish with more gain is usually needed. Increases in gain are small and require serious increases in aperture. (Dish diameter)

As there was no money available for a big, new, satellite dish I went in search of a secondhand dish. By pure luck I spotted an obviously neglected dish lost in an overgrown hedge beside a rural building site. Finding the owner of the site was very easy and I duly contacted him. We eventually agreed a very favourable price and I was now the new owner of a very old 6' (180cm) and shabby fibreglass dish.

The dish came with a simple, but sturdy, alt-azimuth mounting typically made of heavily built, galvanized steel. The previous owner helped me to lift the dish into my trailer where I lashed it down for the journey home. The original steel pole in its heavy concrete foundation was left in place. I already had a suitable mounting base supporting my smaller dish back at home.

I was quite fearful of my wife's initial reaction to such a large object entering our own rural garden. Its cosmetic appearance did absolutely nothing to endear itself. Several decades growth of dark lichen badly disfigured the once-pristine original white surface. Yet again luck was on my side and she helped me to move the trailer and dish into the shelter of a tall, ornamental hedge. Gales were blowing at the time and satellite dishes are renowned for their ability to catch the wind. There was almost no wind to speak of sheltered safely behind the hedge.

I seemed to be having a run of luck because the screws holding the dish to the mounting came undone without a struggle. The mounting was removed from the dish and placed aside. While the dish itself was left face up in the trailer for easy access and stability.

Next came the removal of the very rusty feed support arms. This is a prime focus dish so it has an LNB holder centrally placed in front of the dish. The three equal length, tubular steel arms were placed safely aside for later checking and careful measurement. A satellite dish has fixed optimized geometry for maximum sensitivity and efficiency. So I had no plans to spoil the original design during my "makeover."

So began several hours of scrubbing away at the lichen with saucepan scouring pads. (used wet) I later added household scouring cream to speed up the lichen removal. Care was vitally necessary to avoid working my way through to the active reflector surface. Which I presumed was a very fine, metal mesh embedded beneath the fibreglass surface.

The dish surface was actually micro-dimpled. Which is sometimes referred to as "orange peel." Probably from a course, finishing, spray coat. My efforts at cleaning tended to scour the tops off the raised surface but did not reach deep down into the countless dimples. I tried some fine abrasive paper on the much darker areas but it had little effect and produced a lot of chalky powder. So I quickly decided not to continue with the emery paper to avoid possible damage.

As the dish slowly became cleaner the removal of the manufacturer's name became an increasing priority. The thin, dark blue, vinyl lettering had hardened with time but was still incredibly tough. The plastic film had lifted around the ragged edges, cracked and bubbled. Producing further ugliness to disfigure the face of my, still less than lovely, "new" dish!

I tried various scrapers and tools with almost zero effect before finally taking the bull by the horns. I took out a long handled, flat, wood turning chisel with a half round cutting edge. Which I left safely blunted from long disuse. With great care I was able to safely remove most of the hideous lettering. Though there were still pale halos, shadows and darker, former adhesive areas, where the lettering had lifted over time.

Now I returned to more hours of rubbing with scouring cream and a heavier duty, fibrous, sponge backed, scouring pad. Eventually the remains of the lettering and recalcitrant spots of dark blue plastic gave up the struggle. I suppose I could have bought a polishing mop and car finishing abrasive cream but thought better of it.

The finish is still far from perfect but at least it no longer assaults the eye. The manufacturer's name is now a strange optical illusion rather like persistence of vision. I highly recommend a trailer as a work bench. It allowed solid support and very easy rotation to work on different areas of the huge surface.

I tipped the dish up when it rained and overnight because so much water was collected in the deeply curved surface. At 28cm (or nearly a foot) deep in the centre such a large dish can hold an awful lot of water! Since the dish was not designed as a fish pond the sheer weight of water could easily have damaged it. Satellite dishes are usually set up at an angle so shed rain easily. There is a small central spot which I could have drilled through but didn't want to spoil anything.

Click on any image for an enlargement.

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