[P10] All our yesterdays

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Reception with the 6' dish may be partial but it does offer hope of marginally greater success. I have discovered that there is a small range of options for a much better site for the big dish to the north of the house. Invisible from the road the big dish will pass completely unnoticed.

The iron base has to be moved anyway to make better foundations. This also involves moving a load of cast concrete posts. Which were weighing the base down to protect the dish against rocking in the wind. Or blowing away altogether! Despite my original confidence in the stand it now rocks slightly with firm hand pressure on the mounting. Wind drag on so large a surface easily invites rocking. Particularly when rearward lift is caused by side-on winds using the curvature of the dish. No unlike an old fashioned aircraft wing when placed upside down in the wind.

The dish position I have been using for years is badly affected by the wind. Though this site is also the most convenient for a short cable run to the house. A few extra meters of coaxial cable will do no harm with a high output, Inverto Pro LNB fitted. A hedge is slightly infringing on one side of the present dish position. Which may reduce the signal very slightly. The outer edges of the dish having by far the most area compared with anywhere nearer the centre. The new site offers unobstructed skies at the desired satellite's local altitude.

My idea to use a cheap, round, shaving mirror to check feedhorn alignment worked rather well. First I had to dismantle the rather flimsy, metal framed, shaving mirror. Then I taped the bare, flat mirror absolutely centrally onto the big dish's surface. By climbing a builder's stepladder I was then able to easily check feedhorn alignment. Simply by moving my head, with only one eye open, in a circle around the LNB/feedhorn while watching the feedhorn's reflection in the mirror.

Trying to see if the feedhorn is aligned by looking from the side is all but impossible. There are no visual clues to suggest whether it is pointing at the centre of the dish, or not. These cheap, shaving mirror elements are very thin and lightweight. A couple of pieces of sticky tape, one at the top and the other beneath easily held the weight of the glass. The dish helps by naturally leaning backwards to point at the satellite at 25 degrees altitude. A vertical dish would not offer such security against the mirror falling.

Interestingly, the curved, magnifying mirror element had virtually the same calculated focus as my big dish. (Which I confirmed by focusing an image of the sun on my hand) Unfortunately this mirror produced only a very distorted and highly magnified reflection of the feedhorn when fixed to the dish and seen from behind the LNB.

We are getting only a few short hours of steady pictures and uninterrupted sound around lunchtime. I doubt I can improve much on this rather poor performance with this very old, 6' [180cm] C-band, fibreglass dish. We seem to live under, or very close to, the so-called null line. Which runs north and south right through central Denmark.

To the east of this line there are quite a number of reports of satisfactory reception in the Copenhagen area on quite modest dish sizes. While I know of one, even larger dish than mine, only a few miles east, which gets only slightly longer viewing hours. Morning and evening viewing is still impossible under the null line. There are hardly any reception reports west of us in Jylland/Jutland. When, in theory, it ought to offer far better reception.

Only a much larger dish, or moving home,  offers hope of improved reception over a longer period each day.

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[P9] The simplest answer is often the best.

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I decided to get rid of the arm/boss brackets altogether. However, the boss was a tough piece of aluminium plate which had been hydraulically pressed. The last thing I wanted was to ruin it. So I trapped the centre of the boss very tightly between two disks of MDF in the vice. I could then tap the ears with a plastic headed hammer until they matched the angle of the arms. All without damaging or marking the boss. It took several attempts and I had to check the angles carefully before I was fully satisfied. Had the centre of the plate boss itself been bent the (skew) clamping ring would no longer have fitted. Nor would it have held the feedhorn flat on the boss.

I found that having the wrong angle on the boss ears bent the support arms. This pulled the feedhorn all over the place as I tightened the arm holding screws. Eventually the angles were all correct and the arms now straight and relaxed. By a fortunate coincidence they were also exactly the right length!

Focusing is now very easy just by tightening or loosening the arm fixing screws equally at the dish's rim. The feedhorn can now be easily set in focus to the exact millimeter.

The mounting is now firmly fixed on my massive support pole. Which started life as the base of a professional drawing board. It had a hydraulic lift when purchased cheaply in a flea market. Its massive, flared, cast iron base is further loaded with concrete bars to hold the dish down in high winds. The 'pole' itself is a very thick-walled, steel pipe of 70mm diameter. Sadly it can no longer move up or down after years of exposure to the weather.

The mounting now offers slow motion adjustments in both elevation and azimuth. With the dish being so large (6' in diameter) it has a very small field of view. Trying to turn the whole dish around the pole would be far too coarse a change in angle.

The new, hot galvanized, elevation screw ideally needs spacers so that the nuts can turn more easily without friction. The nuts are also partially enclosed by the pivot support bracket. So spacers would expose them better for the use of a spanner/wrench. Not that this has proved to be a particular problem but I do like to avoid such minor problems where possible. I have replaced some of the rusting mounting screws with stainless steel. As are the new feed supporting, arm fixing screws.

While I can easily get the stronger channels there is still absolutely no sign of the weaker ones. This is a very disappointing result given the time and effort spent on this project so far. I am receiving reception advice from satellite forum members far more expert and experienced than I. Installing satellite dishes for successful reception has never been so difficult as with this one. All due to the weakness of the intended signals.  

Following expert advice on the Astra2 satellite forum I concentrated on a particularly strong channel on the same satellite. By paying careful attention to azimuth, elevation, focus and skew I was able to raise the signal Quality reading to a much higher level than before. The cheap Satfinder meter was not remotely up to the task. Showing increased signal level and audio output just as signal Quality fell on the TV screen.

Once I had achieved the best possible alignment I was able to obtain many of the weaker channels in the UK Spot Beam. Sadly my success was short lived. These same channels became too weak to show smooth video and continuous audio shortly afterwards.

Since the strong channels went on getting stronger and showing even better Quality I think I can safely conclude that the dish has not moved. Either the dish is not large enough for my location. Or it is simply not efficient enough to offer long term viewing at all hours of the day and night. One could say that the journey was rather more interesting than reaching the final goal. I am now suffering from severe project fatigue and considering my options.

Click on any image for an enlargement.

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[P8] A rethink.

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Struggling to overcome the angular difference between the feed boss and support arms blinded me to the obvious. Turn the problem on its side using small pieces of alloy angle to connect the components together. Problem solved. (Tomorrow)

Well, I solved the mismatched angle problem but introduced unwanted rotation. My use of square tubing (for supposedly extra stiffness over angle) offset the arms too much. When, ideally the arms want to be radial to the LNB/feedhorn.

Easily overcome by the use of metal angle instead of box section. Ensuring the arm clips overlie the boss fixing bolts will reduce offset to the absolute minimum.

Note that the feed boss is still reversed. When I tried it the correct way I'd need much longer arms to push the feedhorn out to the focal distance. I don't want to change the arm unnecessarily at this point. At least not until I settle on a practical way of holding the feed head perfectly still.

I still like the arm clips but need to reduce their ability to rotate around the arms. Any offset from radial greatly increases the torque on the clips due to imbalances.

I'm not sure the rubber boot on the LNB works. There is a bump on the LNB casting which might encourage rainwater entry. Self amalgamating tape is probably a better option but not until the design and tuning are complete.

Well, I've had to give up on the clips. They rotate on the arms too easily. I made some angle brackets, again using the clips, to make the arms radial. The head still flopped about.

Now I've flattened the brackets to the correct angle to match the arms to the boss. I'm using more expansion sleeves on the inner ends of the arms and bolting the boss direct to the brackets. It's a fiddle to get the focal distance to the feedhorn correct but I'm getting there. Finding enough screws and nuts is always a problem.  When it is finalized (famous last words) I'll use stainless steel fasteners.The image shows the latest iteration. Provided all the nuts are tightened with the head aligned it stays absolutely still. Focusing can take place by adjusting the nuts.

I have now removed one nut from each of the screws holding the boss. This achieved a better focus. The strong channel is back with the Satfinder shrieking right down to almost no gain on the control knob. This equated to 5 bars out of 8 for Signal and Quality on the satellite receiver.  

Click on any image for an enlargement.

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[P7] It's all in the detail.

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A fresh search of the shed found a pot of assorted plastic pipe clips. I really ought to add more storage space for glass jars. Just to avoid having so many things sitting invisible and forgotten in stacked boxes on racking.

There were several unused 12mm clips so I immediately replaced the strip metal clamps on the dish. The angles of the arms in the clips were still just a little awry. So I drilled out some small rubber tap washers and placed these over the screws between the clips and the boss. This allowed the clips to settle firmly onto the pipes with the rubber taking up any variation on angle  between the feed boss and the clips. Ideally I need some wedge shaped washers. The sort of thing found on some bicycle brakes might do. Once I decide what I intend to do in the long term I will replace the present, overlong screws with shorter stainless steel ones. 

Now I was able to remove the short studs at the rim, arm support brackets. Since I no longer needed any adjustment there. I was now able to use the short stainless steel, hex head screws and expansion sleeves as originally planned. Though I will need new Fischer expansion sleeves if I intended to add smarter arms.

All focus adjustment now takes place at the pipe clips. They really do hold incredibly tightly! Requiring considerable finger strength to slide them along the feed support arms. The head assembly is now much tidier and solidly secure against random movement. Once I find the optimum focal distance for the feedhorn I could drill through the arms and secure the clips permanently.

A standard rubber boot slid nicely over the base of the Inverto LNB to keep moisture away from the coax F-plug. I also taped the cable to the lower support arm to keep things neat.

Jobs still to do include longer pole clamping screws. To enable a solid purchase on the smaller 70mm pipe. Except that I don't have any handy in that size. Particularly in hot galvanized or stainless steel. Another trip to a DIY superstore will provide these. Then I can fix the dish accurately on that recalcitrant satellite. A suitable packing piece will give the rest of the screws something solid to work against. Where one of the four welded on nuts has stripped its thread. Much easier than finding a welder to add a new nut to the galvanized mounting sleeve. With all the attendant problems of disfiguring rust and toxic fumes.

I also want to clearly mark the centre of the dish to speed up alignment. A piece of electrical tape will do for the moment. It is far too cold and windy to spray paint.

A flange on my focus checking spacer pipe would be handy to ensure the feedhorn is pointing at the centre of the dish. The flange will sit true on the dish surface during alignment checking rather than wobbling about on its 2" diameter. Though it will need a perfectly straight spacer tube to work as intended. A tube to sit in the outer scalar ring with a long pointer for feedhorn alignment on the centre of the dish makes even better sense!

It's odd how much smaller the dish looks in profile and even from behind compared with the view from the front. The boundary hedge is winter bare at the moment. So the dish will disappear more once the hedge is in full leaf. If the dish proves itself on the target satellite I might even consider a lower stand. Just moving it back, or resiting it completely, would reduce its visual impact. The high output LNB would allow a longer cable. Rather than its present situation as close as possible to the house.

Click on any image for an enlargement.

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[P6] Feed boss angle problem!

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The angles on the new boss are obviously designed for through-the-dish support arms. See the image where the new arms are fixed at the rim brackets. (Just like the originals) I used handy wall plugs just to prop the inner ends of the arms in place.

The difference in the angle where the arms meet the new boss is so large that I cannot just make the holes larger and crank down on the nuts. I need to keep the boss perfectly flat so that the skew ring and feedhorn lie perfectly flat and true to the dish. So trying to bend the boss will guarantee it all ends in tears.

I think the only simple way around the problem is to make small brackets. These will match the angles at the cost of greater complexity and some cosmetic untidiness.

Though I could bend the arms the aerial tubing is seam welded and not particularly tough material. Bending the arms would be a finicky job trying ensure the boss ended up at exactly the correct height and perfectly square to the dish. Nor do I presently own a pipe bender and the cheapest tend to distort the tube.

Or I could drill holes in the dish and make shorter arms held by dish-penetrating screws, load spreading washers and expansion plugs.

Problem solved! I just found a 12mm plastic pipe clamp which will hold the arms very firmly. While still allowing sliding motion for focusing. It just required the feed boss to be inverted. The feedhorn and clamping [skew] ring fit just as well as before. There was no room for the arms to go under the ears but they easily fit on top instead. I just need to obtain two more clips from somewhere. I can no longer remember where this clip came from.  

My first attempt to use the white plastic clips with inverted boss proved to lack clearance for the feedhorn. The clip has to go on top of the boss.

Then I found some simple metal clamps to fix the feed temporarily to the arms but ran into all sorts of other problems.

The mounting was intended for 80mm pipe and my existing pole was only 70mm. So I turned a brass cap for the pole to locate the top within the 80mm  socket and to stop it moving. Then I discovered one of the threads on a welded-on pole clamping nuts was stripped. So I couldn't clamp the mounting firmly to the pole even with the pinch bolts fully screwed in.

Getting the dish up on top of the existing pole was a real struggle. In the end my wife had to help me walk the dish and mounting up a ladder until it could be dropped over the pole. The pole was far too tall for the prime focus dish and the dish itself looks absolutely vast from the end of the drive.

I quickly obtained one strong channel on the satellite but could not get anything from the weaker ones. The strip metal arm clips I used were far too flexible and the feedhorn was too far from the dish. So I brought my checking spacer tube into play to reset the feedhorn to the correct focal distance. I shall just have to find more of the strong plastic clips to ensure stability of the head once adjusted.

Then the top security nut on the elevation screw proved to jam on the bracket to dish fixing screw heads. So I had to dismantle the entire elevation screw and turn the nut to half the thickness in the lathe and then dome it to ensure clearance at all angles of elevation.

After all these issue were resolved I had moved the dish well off target and could not get the strong channel back despite the Satfinder meter screaming its head off.  I have a tiny 4" B&W CRT TV which I used as a monitor for the satellite receiver alongside in the garden. A larger, colour monitor would be a vast improvement for reading signal quality bars but I have nothing suitable for outdoor use.

I was convinced I had the correct satellite but it wasn't. I checked Satpointer again on the computer and found a distant building to align on. As soon as I turned the dish that way the strong channel was back. Still nothing from the weaker channels. A long, tiring and frustrating day with little real progress to show for it. Though I did get the dish mounted and a signal from it.

I learned today that the Satfinder meter doesn't care which channel is selected on the receiver. It will scream on every satellite it finds. It also makes a different tone on each transponder.

I also learned that I should take nothing for granted until proven correct. I wasted at least an hour searching for a signal on the wrong satellite. With the mounting flopping about on the pole I was constantly losing my elevation setting as well as azimuth. Today was still, overcast and spitting with rain. Tomorrow gales are forecast. I just hope the dish stays on the pole! I shall have to lash it down before going in search of more white, plastic clips.

Click on any image for an enlargement.

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[P5] New Feedhorn, boss and C120 LNB.

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My new IRTE 0.4 feedhorn, sturdy, triangular support boss and Inverto Black Pro C120 LNB have arrived. Four days from a Sunday afternoon, online order is terrific service from Satellitesuperstore in the uk!

 http://www.satellitesuperstore.com/universal_feedhorn_for_prime_focus_dishes

There is no linear (focus) adjustment on any of these components. So I will have to make any adjustment for best focus using the support arms. I had planned to use short stainless steel screws for cosmetic neatness. Now I will have to introduce some studs (screwed rods) to allow some length adjustment. I can always trim the arms to length and use shorter screws once I have the focus optimised.

 

The clamping ring allows rotation for skew of the LNB. Note that none of the screws have been tightened in these photographs. All the screws are stainless steel to avoid long term rust. Zinc plated fasteners are complete waste of money for outdoor use. Split spring and plain washers are provided to ensure long term security of fastening. While maintaining the ability to rotate the LNB without tools.

Both the feedhorn throat and LNB have a protective plastic film to avoid spider and moisture ingress. An O-ring is trapped in a circular groove in the face between the LNB and feedhorn. The screw should be tightened enough to bring metal to metal contact.

The triangular boss will provide a much neater and more secure fixing of the feed head compared to the original plastic ring and push fit arms.

The whole arrangement is a far more modern and professional looking set-up compared to the original.

View inside the scalar rings of the feedhorn. Overall diameter is 75mm or 3" in old money. The scalar rings are supposed to allow the LNB to see the entire dish without any reduction in true aperture. Nor allowing 'noise' to sneak around the edge of the dish.

I shall make a tubular spacer to support the feedhorn on the centre of the dish. Then I can measure how long the new aluminium arms need to be.

The view inside the Inverto Black Pro [IDLB-SINF01-OOPRO-OPP] LNB throat showing the two small antennae. One for vertical and the other for horizontal polarity. The protective film makes it difficult to capture the fine detail. This image is skewed to avoid reflections from the plastic film. The internal arrangements are concentric to the throat.

The whole LNB is tiny in comparison with many other similar devices. The Inverto Black Pro has a very good reputation on the satellite forums. It's high output and claimed 0.2dB noise level is suitable for high quality, longer cables back to the receiver. Cable lengths of up to 70 metres are claimed to be possible.

This allows considerable freedom of siting of the dish. Not a matter to be lightly dismissed when it comes to a very large dish in the built-up environment. The equally well respected Invacom LNBs are low output and thus limited to much shorter cable runs. It was this factor which tipped me towards the Inverto product.

Click on any image for an enlargement.

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[P4] New support arms needed?.

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The dish is 180cm wide (D) and 28cm deep(d) measured down to the centre from a string stretched tightly across the diameter.

The original feed ring height is 68cm to the underside. (i.e. The face pointing down at the dish)

The formula for focal distance F =  D^2/16d

180 x 180 = 32400   16 x 28 = 448 So F = 32400/448 = 72.32 cm

Calculated Focal length from direct dish measurements = 72.32cm

So there is a physical discrepancy of 4.32cm somewhere!

The focal ratio of the dish is F/D = 72.32/180 = 0.4. This figure is used to adjust C120 LNB feedhorns if necessary. Though, by coincidence I have ordered a fixed horn suitable for F/D 0.4 dishes.

The plastic spider screen on the original Ku-band LNB (with built in feedhorn) lay flush with the underside of the plastic ring. Due to its rather amateur method of attachment one cannot automatically assume this feedhorn position was correct. Nor that the ring and arms were even designed for LNBs as we know them today. The dish is quite possibly from the 1980s. So may have been designed for C-band LNBs of the time. Or even some other unknown type of feed.

What we can assume is that the support arms are unchanged from new. Only the manufacturer could have formed the "plug" ends of the arms. The other ends have captive screws which are very unlikely to be anything but original. They are rusted solid.

 I have now decided to ignore the original layout. The calculated focal distance is 72.32cm. This is where the feedhorn mouth should sit (+/- a little) To allow some leeway I have cut a spacer tube of 72cm to support the feedhorn and boss. I shall use this arrangement to measure for new, light alloy arms.  The dish will be laid flat on its back for this exercise. Note how far the true focal distance extends beyond the original feed support ring!

My first arms will be made from scrap 12mm aerial tubing. Of which I have collected quite a lot from large, redundant (German TV) aerials. These were once very commonplace in TV-starved Denmark. Limited to a few hours of monopoly, Danish TV. Most of the houses in Denmark had these very large aerials on the roof.

Or mounted on high lattice towers where the landscape did not allow a clear line of sight from the rooftop. Many still have them. The lattice towers, of many different heights, still stand around in the landscape. That the Danes were willing to go to the trouble and expense to put up these towers and aerials just to receive terrestrial German TV must speak volumes about the domestic, Danish transmissions.

Sadly most of my alloy tubing is in need of straightening. Once I have confirmed best focus for the new LNB and its feedhorn I can make some much smarter arms with new tubing. Assuming, of course, that I can receive the satellite I am aiming for. Otherwise, no matter how enjoyable, all my work, and modest expense, will have been for nothing!

Click on any image for an enlargement.

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[P3] Feed support.

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The original (three) feed support bars are made of steel tube. If they were ever galvanized it does not show.


 The feed holder is a heavy, white, plastic ring.

The inner ends of the arms are slit, tapered and lightly knurled where they have only a push fit in the plastic ring.

Three holes are bored at 120 degree intervals for the tips of the support arms.












As purchased, the old, Amstrad, Ku-band LNB, with built in feedhorn, was screwed to the ring via a crude and ridiculously over-sized piece of alloy angle. The head was anything but straight and seemed very prone to accidental flexure. The three holes in the ring suggest it once had a neater clamping plate which would have allowed rotation adjustment for LNB skew.






The arms are now rusted and very ugly. As are the captive fixing screws which fit in small brackets bolted to the outer rim of the fibreglass dish.

I have resolved to replace the feed support arms with good quality alloy tubing. I have also ordered a new central boss of aluminium plate with an LNB clamping ring to allow for skew.

The other advantage of the new central boss is that it will allow firm, screw clamping. While a triangular pyramid (tetrahedron) forms a naturally, very stiff structure it relies heavily on the connection points being firmly attached. The old design was very weak at the top of the pyramid!

I believe that the 12mm OD alloy tubing and threaded clamping at all connection points will provide a much more secure head assembly.


I found these Fischer expansion sleeves in a local DIY store. They fit the inside of my alloy tubing and will expand to lock permanently in place when an inner cone is pressed home by the screw. I don't believe the cone can be retracted once pressed home. The female thread in the sleeve will then hold the necessary screws for support arm fixing. The short M8 stainless steel screws and nuts were bought separately and were not part of the expansion device.

For cosmetic reasons I could saw off the screw heads and have two nuts to clamp to each dish bracket and the central boss. I am still pondering whether to do this. The next post will show the new boss, feedhorn and head assembly. I am now waiting for these items to arrive in the post.   

Click on any image for an enlargement.

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[P2] Altazimuth mounting repairs.

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The heavy altazimuth mounting which came with the dish was in fair condition. Except for the elevation screw. Which had rusted badly over the years. Two of the three nuts could be turned with great difficulty. The third was stuck fast despite repeated applications of penetrating oil. 

If I was to replace the entire elevation adjustment screw I needed the two alloy pieces which formed its pivots. I finally decided to sacrifice the rusted rod and cut it where I could remove the alloy fittings with least effort. 

I left a stump of rod below the top pivot piece to grip in the lathe chuck. This allowed me to centre drill and bore out the rusted stud in the top pivot piece in the lathe.

The alloy had originally been threaded to hold the top of the screwed rod. Rust had taken its toll and I could not remove the rod from the alloy fitting. 

By the time I had freed the threaded rod with careful boring there was no thread left in the alloy piece. I thought I could easily overcome this problem by fitting another nut on top of the pivot piece. For the modest dish elevation angles, which I would be using, the nut should never get in the way.

An image of the top elevation pivot fitting after drilling, boring, cross-drilling and a new, hot galvanized elevation screw (stud) fitted. The top shows the dealer's colour coding paint rather than rust.

The pivot bolt itself passes right through a cross drilling in the threaded rod. Which I drilled in the vice on the bench drill after tightening the two security nuts. 

I also turned a slight flat on the top of the alloy pivot piece. Just to give the nuts more surface to work against and to lower its profile.

Lower elevation screw, pivot piece. The alloy is a clearance fit on the large elevation screw. The ends are  threaded for the two pivot screws. A cross drilling would just lock the elevation screw in the fitting. All the visible nuts seen here are used as lock nuts. Dish elevation requires one of  the large galvanized nuts to be loosened so that the other can be turned. Fine adjustment for elevation is then possible. Major changes in elevation would require one nut be backed well off to allow the elevation screw to slide freely through the fitting.

 

Here is the fine azimuth adjustment  on the main crossbar. Azimuth can be roughly adjusted by loosening the holding screws on the pole and turning the whole mounting (and dish) but this can be far too coarse an adjustment. Particularly with larger dishes. Which have a very narrow signal acceptance angle.

Most of the screws on the dish mounting are badly rusted and should be replaced with either new, hot galvanized screws and nuts or stainless steel.

 

One of two dish elevation brackets pivots on this bolt screwed into the end of the main cross arm. Again rust has taken its toll and the screw should ideally be replaced.

Do not confuse hot galvanized with electroplated zinc. The latter finish is bright and attractive in the shop but rusts rapidly out of doors. Hot galvanized is very dull grey and often shows surface "crystals."

While a hot galvanized finish can protect steel for decades any damage can weaken the protection. Even applying a spanner/wrench to a nut or screw head can cause a break in the protective surface. Chemical reactions can also occur at screw threads. Which may break down the protection and cause rust to form. 

Click on any image for an enlargement.

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[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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