5.03.2022 Finally taking the 2.2m dish down.

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 Saturday 5th March 2022. The end of another era and eight years since my last post here. I finally took the unused 2.2m dish down. Once Astra 2 became too weak to receive anything useful the dish had just been making the garden look even more untidy than usual. There is little incentive to keep things tidy. As old age and complete, rural detachment take their toll.

 Fortunately I had carefully chosen a dish mounting site. Where it was invisible outside our rural garden but could still see the satellite in the sky. I had even turned the dish on its post occasionally. To avoid catching the worst of the wind during storm alerts. Though a vast, conifer hedge had also helped to protect it over the long years.

 The dish had gradually discoloured with moss and lichen over time. Which did not make it any more attractive. Nor had toned it down much. Not compared to when I manually buffed the finish to brightness on first arrival. I used fiber faced, dish washing, scouring pads and bathroom, abrasive cleaning fluid. Gentle but effective given enough time and effort. I didn't want to expose the aluminium. Just clean the top surface of the special finish.

 Forward to today and I removed the LNB arms. Using a brand new Bahco plumbers wrench to hold the arm tubes still. While I unscrewed the stainless steel, hollow, fixing bolts with a socket wrench. These bolts had always been immovably fixed by a chalky thread locker. The manufacturers obviously didn't want their dishes blowing off the vast, lattice towers. Which still dot the Danish landscape. A distant memory from local, cable TV. Many Danish villages would have a mast and an Antenna Club back then.

 Rather optimistically, I had repeatedly sprayed these errant bolts with penetrating oil over the years. This time the bolts actually came undone. With the help of the sharply toothed pipe wrench. Further aided by a 2' /60cm length of steel pipe. Used as a lever on the socket head bar. Without the feed arms I had much better access to the dish for lifting it down. Not to mention much easier storage.

 Then I used my familiar builders folding stepladders as a crane. The ladder's long, steady bars were firmly lashed together with rope at the top. Then used to support a cheap, chain hoist. The picture [left] was taken back when I was first erecting the dish on a steel post. Which was sunk into a meter of concrete. It would be suicidal to use normal ladders this way. The stability bars at both ends are absolutely essential.

 The feed arms would not come off back then. So I had to work carefully around them. The steel post can be seen to the left, hiding behind the dish. It's fresh, concrete base still wrapped in polythene. To stop it drying out too quickly in a heat wave.

 Yet again I bridged the rear dish's reinforcing frame with multiple loops of rope. Then hooked the hoist around that. Taking the weight of the dish on the hoist allowed me to remove the altitude pivot bolts. The dish was then let gently down to the ground while still upright. 

 There followed a struggle to roll the heavy dish, on its reinforced edge. To a secluded spot in our rural garden. To finally come to rest against yet another, overgrown hedge. Where I added the 1.8m and 2.2m dishes to the stack. [Top picture] 

 A tall, dense, wild hedge ensures they will remain completely invisible from outside the garden. Such large, round objects can be seen for miles against a green, rural background. Cheap tarpaulins will soon die of exposure. So that isn't a suitable option for achieving invisibility.

 At this stage I am really not sure whether to advertise the dishes for sale. They won't deteriorate. So will come to no harm until I am long gone. They no longer owe me anything in monetary terms. I am very unlikely to get much for the dishes. Which makes visits by strangers a security and possible heath risk for little reward. [Covid]

 I had great fun playing with all of my dishes, in their day. Even if,  in the end, it was all for nothing. Netflix eventually replaced our standard, British TV fare. Making the struggle to receive the patchy Astra 2 signal completely pointless. Ironically it was my wife who liked British TV. I was never much of a TV watcher. 

 Netflix hasn't improved much over the years. Though that may just be our being located in Denmark. Does the content vary by region? Long weeks pass without anything we really want to watch. Usually when our favourite series are endlessly promised new seasons.  Which only leaves us with YouTube. Which has immensely variable content but is utterly spoilt by cluster bomb advertising. That's a commercial dictatorship by sociopaths for you.

 I have been downsizing and clearing decades of accumulated "stuff" recently. The big dish was just one more hurdle [or burden] to remove. I have carefully detailed how even a 75-year-old can manage such tasks in relative safety. Just in case it helps. 

 Don't blame me if you hurt yourself while trying to copy my methods. I obviously can't be there to supervise. I strongly suggest you have at least one other, strong adult to help you. Never work with a big dish in windy conditions. They act as a sail. Generating tremendous lift at some inclinations to the wind. You have been warned! I chose a day of dead calm in a very sheltered garden. Mounting such a dish on a post requires a very sturdy steel post/pipe and lots of concrete in the ground! Do your homework before even considering the task.

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I'm streaming of a white Xmas?

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The complete absence of evening TV entertainment has forced a trial period of Netflix.dk. We have been rather enjoying a number of British and American TV series but cannot recommend most of the rather dated films on offer.

Overall, the Netflix.dk catalogue is very limited indeed. A common criticism of Netflix.dk. The relatively low subscription cost per month [79DKK in Dec 2014] makes the streaming exercise fairly painless. Were it not for the fact that Denmark enjoys [by far] the smallest catalogue despite having the world's highest charges for Netflix! Or so the rumour goes. An odd combination but deeply traditional state of affairs for Denmark. Where choice is always extremely limited but prices are always far higher than anywhere else! Most supermarkets stock exactly the same products regardless of the name above the sliding doors. Only the asking price and poor quality of service varies slightly.

The forced [Scandinavian] subtitling on Netflix has also proved a considerable irritation. Though it was much reduced by making the text as small as possible and in black italics. I exchanged a few words on their customer service chatline on the subject. Though it was a complete waste of effort reading their empty auto-excuses.

All they need to do is provide a default OFF button for subtitles on all titles. Or a transparent, or really tiny, preferred text option. Some series have an awful lot of foreign languages spoken in what are basically English series. [Heroes for example has loads of spoken Japanese which probably narrates the story] Without the [default Scandinavian] subtitles much of the plot is probably lost. Further exacerbating the torture of having missing or ridiculously obtrusive subtitles in the middle, or even, the top of the screen! For which, read: "Netflix' amateur night!"

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A threatening storm finally precipitated the removal of the long-disused 1.8m GRP dish from its massive mounting pole on the front lawn. I used the same method of two folding [builders] stepladders. These were straightened out [via the ratchet hinges] and tied together at the top above the dish. A 3/4-way pulley system was then used to lift the dish and altaz mounting safely off its sturdy pier. Once the dish had reached the ground it was easy enough to roll on edge to a safe position before laying it face down on the lawn. The feed mounting bars having been unscrewed prior to work commencing to avoid damage. I'm rather glad to see the dish come down as its round white face was distantly, but distinctly visible from the road. Once face down the offending dish shrank to almost insignificance.

Meanwhile, the 2.2m aluminium, Siemens dish still provides 2E British TV reception for a few hours per day if required. Though only from somewhere before lunchtime to some random hour in the afternoon. Reception hours vary considerably without any obvious cause due to weather or even season. My intention to add slow motion in azimuth has not occurred. The pressure to perform fine tuning has receded thanks to the TV streaming service. Though what we'll do when we are reduced to watching much less interesting Netflix fodder is a bit of a concern. Hopefully the catalogue will continue to expand to match the phenomenal growth in subscribers.

 NOTE: This post was edited at Google Blogger's request 14.04.2023 to remove all reference to adult content on Netflix. Ironically, my highly cynical and negative comments were deemed unfit for a younger audience. i.e. Those I was trying to protect. Since my original post, Netflix has gone on to offer a huge catalogue of mixed content. Their subtitles have also become much more sophisticated. You must judge for yourself whether some content is suitable for viewing  by children.

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Gilding the faded lilly

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It is now half way through September. Months have passed since my last update. I wish I could report improved reception but it remains highly variable without obvious reason. We lost the signal very early the other day [3pm] so I re-pointed the dish for signal Quality on Astra 2E UK Spot Beam.

It seemed that the U-clamps on the steel support post had worked loose. Allowing he dish to rotate sightly in the recent high winds. I was even able to push the dish around the post by hand. It is highly likely that I had re-adjusted the dish at some point and simply forgot to fully re-tighten the 19mm nuts on the U-clamps. 

So far the coax cable had been held to a feed support arm with tie-wraps. This had allowed changes in skew of the LNB depending entirely on [arbitrary] cable tension. I resolved to do something about this.

Sadly the dish to arm fixing nut still refuses to budge. I even brought out a vice and clamped that firmly to the arm to have some resistance to work against. Then I applied a 3' pipe to a hex socket bar without the least change in tightness of the nut. It really seems to be fixed for life. I had discovered a white powdery material when I had finally been able to remove the top nuts at the feed end of the arms. The enormous effort involved in their removal suggests some sort of thread locking compound. Or, at least, one that had dried hard over the intervening decades.

Fortunately the stainless steel nuts at the dish end are already bored large enough [7.5mm] for a modern coax cable. So I used a rechargeable drill to bore an 8mm hole in the arm itself not far from the feed. Then I laid the drill gently over while still turning fast to force a suitable exit angle on the newly drilled hole. Finally I tidied up the now-oval hole with a round file. The hole was originally made 7.5mm but this proved far too unforgiving. The cable would not pull through an oval hole without risking serious damage to the insulation and covering. 

Getting the coax to exit the 8mm [oval] hole from within the tubular arm was quite another matter! In the end I made up a stiff wire hook and was able to coax the copper wire core out. Things went much more smoothly after that.

No sooner had I pushed the cable through the arm than a spider moved into the hollow nut behind the dish! I forced an eviction just long enough to take a picture. Whereupon the spider returned to its layer.

Reception still arrives and dies again at highly variable times. Sometimes reception is possible from 8am to 6pm but very often an hour [or two] less at both ends of the day. Weather seems irrelevant except during thundery cloudbursts. Ordinary and even heavy rain seem not to affect matters much at all.

Nothing I try seems to make reception any more extended or reliable.  I am still wary of risking further investment in a new receiver in the vague hope greater sensitivity. Or, rather, a receiver with a lower reception threshold before the freezing and stuttering, presently endured. On the FortecStar Passion HD  this is always when the indicated signal Quality falls below 53% regardless of Signal level.

Should an online BBC TV service ever be offered I'd take down the huge dish without a qualm and finally accept defeat. Only evening TV holds any real interest and then only occasionally. Being limited to daytime TV makes it hardly worth the effort [and expense] of setting up the dish in the first place!  

Click on any image for an enlargement.

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Adapting Invacom ADF-120 feedhorn to Kathrein feed boss.

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Just as a turning exercise in the lathe I made another adaptor to match the Invacom feedhorn to the Kathrein feed boss. Since I had no alloy bar in a suitable diameter I used an old Picador 4" V-pulley for raw materials.

First I fitted the pulley in the lathe with inside jaws fitted to the 3-jaw, Burnerd chuck. Then the boring went smoothly from the 1/2" original to the desired 25mm. I used the Invacom feedhorn as a plug gauge to ensure a close fit when I came close to the correct bore. Then I matched the outside diameter of one pulley flange to the 69.5mm Ø Kathrein original. 

The image shows one side of the adapter. I also ground off the point of the hardened, grub, fixing screw and polished the new, slightly convex, contact face with emery paper. This will save marring the feedhorn throat with the clamping screw. A nylon grub screw would be much better.

The original bowl-shaped feed boss of my own Kathrein 2.2m dish has a matching hole for the original feedhorn.  The critical dimensions are identical to the triangular Kathrein feed boss shown below.

The other 2.2m Kathrein dish has an impressively massive  triangular feed boss. The impression of the skew clamping ring is clearly seen on the upper face of the feed boss. One arm holding screw has been removed for boring out to a larger diameter to take modern coaxial cable.

The skew ring clamps the 69.5mm flange on the original Kathrein feedhorns. Now it can clamp the home made adapter. Allowing the Invacom ADF-120 feedhorn to be used with a modern C-120 LNB and original Kathrein feed boss.

Because of the deeply recessed faces of the Picador cast V-pulley there wasn't enough meat to provide a 60mm seat for the Kathrein skew ring. More by good fortune, than anything else, the three fixing screws of the Kathrein skew, clamping ring will hold the adaptor perfectly central in the boss. The adapter flange is 3mm thick to match the original, Kathrein feedhorns.

While I was using the lathe I bored out the stainless steel, arm fixing screws of the other Kathrein 2.2m dish to match my own. 

This would allow the owner to run modern, high quality coaxial cable neatly inside the hollow, alloy arms. This saves clipping the cable to the outside of the feed support arms with tie-wraps and looks very much neater.

Click on any image for an enlargement.

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Results:

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The erection of the dish on the new pole finally allowed the dish to stay still after adjustment.

Rather amusingly,  Sky News popped up the moment I switched on the system. By sheer coincidence I had aligned the dish perfectly by eye. Getting the UK SB was quite another matter. It needed the dish swinging further East. Then all SB channels immediately became available with reasonable Strength and Quality on the receiver's tuning menu.

Having obtained SQ figures for the IRTE feedhorn I thought I'd better try the new Invacom ADF-120 feedhorn. The problem was a lack of clamping. A search began for suitable raw materials to make a clamping ring. Luckily I found an old Picador 2" V-pulley in cast aluminium.

This I bored out from the original 1/2" to 25mm for a nice sliding fit on the neck of the Invacom feedhorn. Then I turned one side of the pulley to match the IRTE feedhorn's clamping ring. [52mm] Now I could slip the Invacom feedhorn through the newly turned ring and clamp the ring to the IRTE feed boss. The scalar rings were screwed on last. See image alongside.

The change in feedhorns provided an extra 2% on both S&Q. Well worth having! The Invacom feedhorn proved to be rather insensitive to both F/D and focus. I ended up with the feedhorn throat at maximum extension [about 5.5mm] and the scalar rings pressed back against the boss. I then repeated checks for best skew.

I suppose it is possible that the Invacom feedhorn needs a different [more distant] focal point setting compared with the IRTE. Perhaps I should look into this as a potential factor for further gain.

I find it easier to remove the entire feed from the support arms to work on it. This simply involves removing three nuts with a 13mm spanner. A 7mm spanner is very useful when a screwdriver cannot reach the small stainless steel clamping screws for the LNB and feedhorn clamping ring. Swapping feedhorns then becomes a five minute job from start to finish.

It is too soon to say when the UKSB signal will fade. It is only 1.45pm in bright sunshine and clear skies. Many channels were already dropping out by this time when the dish was still hung on the slotted angle stand.

Trying to move the dish when it is clamped to the pole proved the Kathrein mounting was remarkably rigid. Previously I thought the dish itself was flexing. This proved to be an illusion and only the result of the slotted angle members flexing.

I am running just over 30 metres of new coax to a straight connector on the front wall of the house. If I re-route the cable to enter the house from the back I can save ten yards and have no need for the connector. I will wait until I have solid results over a longer period before I decide to cut the new length of cable.

Despite all my efforts so far the UK SB channels started freezing at 17.45pm. Then they began dropping out just before 18.00. By 18.15 there were literally no UK SB channels left. So, still no evening viewing!

Click on any image for an enlargement.

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The Big Lift 2

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Sunday 22-6-2014. On day four, I lost patience with waiting for the concrete to gain full hardness. Justifying the risk of damage as very low thanks to the depth of the concrete and the excellent balance of the dish relative to the pole. I had also used a strong mix of 3.5:1 of premixed sand and gravel (Dansk: støbemix) to cement.

Now I had to find a safe way to lift the dish to mounting level working alone. My wife had helped me lift the 1.8m fibreglass dish by sliding it up a gently inclined ladder. The 2.2m dish was much larger, even heavier and the necessary lift much higher.

First I lifted the weight of the dish off the slotted angle stand using a [2 x 4 pulley] block and tackle. This was supported by two builder's folding stepladders straightened out and tied together at the top. These ladders have the advantage of strong supporting crossbars for the rubber feet. This makes them very stable even when subjected to side loads. Using normal ladders would have been suicidal!

The first image shows the dish lifted off the stand and lowered safely to rest on the ground. I had to be careful to avoid damaging the LNB but it all went well. It had been blowing a gale all day and it suddenly shifted to the East. Making for a few anxious moments as the dish swung gently between the ladders.

The second image shows the rear view as I dismantled the slotted angle, trapezium stand. This was to make room for the ladders to move backwards to the pole. This involved stepping each ladder backwards in turn with the dish slung between them. Finally I was able to move the rear ladder behind the pole and the waiting alt-az mounting.

I don't have images of the actual lift because I was too busy hanging onto the lifting rope and running up and down the ladders.

A double lift was necessary to get the dish high enough to bolt onto the alt-az mounting. This was just a matter of lifting the dish as high as it would go and then tying it off to the tops of the ladders. The block and tackle could then be released, lowered and retied to the dish on much shorter ropes. Allowing the dish to be raised by another foot or so [30cm] on the second lift.

I was lucky and the top edge of the dish just fitted under the peak of the two ladders when the dish was at its highest.

 

I had planned to use a strong ladder, resting on the stepladders, if necessary to get the extra height. In retrospect, I could have set up the ladders over the pole and rolled the dish between them. As I had to lift the dish off the stand first I decided to walk the ladders instead.

Here the altitude pivot bolts have been screwed through the eyes and into the outer ends of the horizontal mounting channel.

The altitude nut has been adjusted to tilt the dish back to point upwards at 25 degrees for Astra 2 at 28E. The dish angle was checked with a digital clinometer laid against a stiff pipe touching the top and bottom lips of the dish.

The Kathrein alt-az mounting is a simple, but very strong, welded construction. Made from two channel sections of steel then galvanized. The two U-bolts hold the mounting to the pole. While allowing the dish to be rotated on the pole to point to the satellite. The nuts can then be tightened to lock the dish firmly on target.

The dish seems to have shrunk now it is tilted back at 25 degrees and raised on the pole. It looked much larger when nearer the ground.

I promise to tidy up the junk from the previous steps. It doesn't look like it now but this is a 2.2 meter dish. [About 7'4" in diameter]

The bottom of the dish is presently 85cm or 33" above ground level. This will reduce by a couple of inches when the soil is levelled and re-grassed. The garden slopes away from east to west by a couple of feet [60cm] over its 30 yards/metres width.






The 4.3" [110mm] heavy, galvanised pipe has been sunk into a meter depth of concrete. [about 3'3" in old money] The square hole was tapered outwards at the bottom and had a minimum cross section of 40cm x 40cm. [16" x16"]

I tidied up the top of the concrete (above ground level) with a ring of cardboard. This had been lying around looking for a purpose. It will probably disintegrate over time.

By this means the last of the concrete mix was raised above the ground without the risk of a frost heave overhang. Untidy hole edges have a habit of allowing a larger lump of concrete to form than the hole itself. In a hard frost the overhang can actually lever the concrete block out of the ground.

The soil will eventually be levelled around the pole and re-grassed for a neater appearance.

Click on any image for an enlargement.

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That sinking feeling:

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Thursday:  The Invacom ADF-120 has finally turned up in the post! There were no instructions enclosed for tuning to the dish's F/D. Fortunately I had already found these online. So I know were the ballpark lies. 5.5mm throat extension beyond the scalar rings should be about right for the 0.34 Kathrein dish. I will keep an open mind rather than allowing this figure to dictate the results.  I have yet to produce a suitable clamp for the Invacom. Which lacks the IRTE's excellent, built-in collar and skew-clamping ring. It might be possible to use the Invacom's LNB fixing flange with a suitable clamping ring. I have yet to compare the two feedhorns side by side.

The Invacom is a nicely turned bit of kit. With a very high surface finish compared with the much rougher, cast IRTE feedhorn. Though the weather will probably discolour the Invacom quite quickly. Not that it matters in either case.

I took the advice of the satellitesuperstore.uk website [though I didn't buy it from them due to the much higher price and £15 minimum European postage.] They suggested adding some petroleum jelly to the fine adjustment threads to reduce the risk of binding. The clear, light grease is visible in the image alongside. The packaging shows the nominal range of F/D capacity. If they weren't going to enclose tuning instruction why not print a graph on the side of the box?

Now back to the pole hole digging! I seemed to have chosen a particularly warm and sunny time of year to dig. There was a transition around 90cm where I could no longer reach the bottom of the hole with my gloved hand. Not even when lying flat on the grass alongside. Up until that point it was easiest to scoop up the loose soil with my gloved hand. Then I ran out of arm length! The high cost of hole borers and specialist pole hole digging implements was quite ridiculous for making just a single hole. None of our collection of  gardening implements helped much with removing the sticky clay. It either couldn't reach or wouldn't scoop up the soil in the narrow confines of the hole. While the heavily offset, trenching spade simply allowed the clay to roll off the tip each time I tried to pull it back up!

I finally resorted to a salad serving spoon from the cutlery drawer of the local charity shop to lift the loose stuff. Then I hit a stone which lay perfectly across the bottom of the hole in sticky clay. Careful scraping around the stone with my salad server allow me to hook a small crowbar under the stone. I was then able to roll the stone up the side of the hole until I could lift it clear.

After that I began digging with a 6' length of Dexion, slotted angle. It made a handy tool in the deep, narrow hole provided I wore hide working gloves to protect my hands. The clay became steadily damper and stickier until I was able to make quicker progress with the clay sticking well to the angle iron. I passed one meter then 110cm. This was my target and allowed 10cm of large gravel to line the bottom of the hole for nominal drainage. Not that the clay was likely to allow much water movement. First I tamped the bottom of the hole well with a fence post and then worked on the layer of gravel.

Finally I was able to lower the very heavy, 2.67m x 114mm, galvanized pipe into the hole. The bottom flange settled nicely onto the gravel but the heavy pipe was still used as a final tamper for bit more compaction. No point in having the pole slowly sink on me over time. My reckoning suggests that, on the mounting, the bottom of the dish will be slightly less than 60cm or 2' above the ground. Enough to get our rechargeable electric mower under the lip without difficulty.

Tomorrow I shall have to buy some bags of ready-mixed sand and gravel and a bag of  cement. I had deliberately kept the hole neatly rectangular and not much bigger than the welded flange on the bottom of the pipe. So it won't take a huge quantity of concrete.

BUT: Some dish manufacturers suggest a cubic metre of concrete for a dish this size. Given that my dish is very well protected by a very dense 10' high conifer hedge, on the windward side and trees and dense shrubs behind perhaps I shouldn't worry too much? The dish has shown no interest in moving on its lightweight trapezium stand so far despite some gales.

Let's think about this before it is too late. Is the deep, narrow hole (and resulting concrete block) likely to be a real weakness in actual practice? The concrete greatly increases the area of hard material pressing against the relatively weak soil compared with the bare 4" pipe. The larger the block the larger the surface area of the concrete. This considerably lowers the surface pressure per square inch/foot/cm/meter. Since the surface area of the block increases on all four sides. Hole/block depth remains the same in all cases. The lower the surface pressure between soil and concrete block the less the soil can compress.

A larger block of concrete obviously has a very much higher overall weight than a smaller one. Increased weight will greatly resist the block and pole/mounting/dish assembly from tilting. Or even lifting bodily out of the ground in a storm. There will also be a considerable increase in resistance from the surface roughness of the concrete where it is cast closely against the equally rough walls of soil.

So increasing the hole size offers quite a number of obvious advantages at relatively low cost. Except in time required for the excavation itself and a little time more for mixing the concrete. The material itself is fairly low in cost. My own time is free since I am a volunteer working on my own project at home. So there are no travelling costs and meals are normally provided anyway. At least so far. Impatience with the lack of TV might prompt industrial action!

I remember setting a tall 4" steel pole in the lawn on a previous unrelated project. I did not use concrete but tried hard rammed stones and gravel instead. The pole quivered at the slightest touch though it remained upright over time. I even filled the pole with sand to try and stop it shaking. This had no obvious effect.

Am I willing to risk the dish shaking in a wind beyond the tight tolerances for pointing common to such large dishes? Decisions-decisions! Making the hole square in cross section, instead of the present rectangular, would double the width. Thereby greatly increasing the mass and the concrete block's surface area. Unless I hit a large stone the work is not too arduous. Certainly no harder than I've managed so far.

Perhaps the limitations of using a 4" pipe will be the determining factor in the amount of flexure under high wind loads? Filling the pipe with concrete [later] would be much stiffer than sand. While telescoping the lower half of the 4" pipe with a much larger pipe, then filling the intervening space with concrete, would help enormously. Except that I don't have any 8" or larger, steel pipe handy.

I could buy a concrete drainage pipe and slip that over the 4" one while it is down in the hole. Not an easy task given the likely weight of the concrete drainage pipe and the intended height of the 4" pole above the ground! Though this idea would certainly lift the flexure point well above the concrete block/ground surface. To considerably shorten the beam subject to flexure.

The concrete drainage pipe need not reach the bottom of the hole. It's purpose is only to shorten the 4" pipe's unsupported length. So I could half fill the hole. Let the concrete go off just enough to support the drainage pipe. Then continue filling the hole and interstitial space between the two pipes to achieve a uniform mass of concrete. Or, I could support the drainage pipe somehow without pausing the fill. Though I don't think this is really necessary.

Perhaps I am just being too paranoid about pole flexure? It's just that we do get quite a lot of storms with high winds. The Gilbertini 1.2m needed a stack of concrete posts as ballast to hold its massive cast iron stand down. The Kathrein at 2.2m is almost twice the diameter and vastly larger [4x!] in potential, wind-catching area. That is four times the wind loading. I had better star digging again even if I don't add a larger transition pipe. This is all beginning to seem like an awful lot of work for only a few hours of British TV around lunchtime!

One sweaty hour later and the hole has increased to 40cm square by 110cm deep. [Instead of the former 20 x 30 x 110cm deep] I shall undercut the bottom of the hole into a truncated pyramid. The so-called elephants foot foundation block. The pyramidal form resists lifting and toppling due to wind loads and greatly improves resistance to frost heave. The larger base also resists sinking on softer ground. [My damp clay] Much better than a simple cylinder. And, very much better than a typical (amateur dug) conical-shaped excavation with the point at the bottom!

The concrete has been put off for the moment. I am still unsure whether the post hole is big enough.

Well, I have decided to go for a simple pole in a 40cm square hole 100cm deep. I have enough sand and gravel mix to fill a hole that big. Now I just need the cement. I have rammed the hardcore again to be sure.

Weds 18/6/14: Concrete completed in windless, hot sunshine and 70F. I mixed the concrete in a wheelbarrow using a rake and 3.5:1 støbemix to cement. Total expenditure 200DKK [about £20] and I still have one and a half bags of cement and some sand/gravel mix left. I have enclosed the casting and lower pole in polythene to retain the moisture while the concrete goes off. Though, after today, the temperature is due to drop and become more cloudy.

I have been monitoring the temperature of the spun alloy, Kathrein dish to see if the thinned surface paint (from cleaning) affects solar temperature gain. Quite unexpectedly, it remains quite cool. There is also no sense of warmth, at all, at the focus while placing my hand over the feedhorn with the sun full on the dish. A good result.Though the risk of frying the LNB is much lower on a prime focus dish compared with an offset one. The latter usually have a plastic cap over the concealed feedhorn where heat might be concentrated. The prime focus dish has a naked, metal feedhorn with little or nothing to absorb heat.

At day four since I poured the concrete I am still waiting for it to gather more strength before fitting the heavy dish on the steel pole. Despite the polythene skirt being constantly covered in droplets internally the concrete surface is always dry when I lift the plastic to check. I have been adding water each time and shading the base from the summer sunshine to keep the concrete cool.

Click on any image for an enlargement.

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