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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Backward Progress?

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Realigning the dish brought back Astra 28E UKSB for the usual short reception period around lunchtime. The feedhorn extension ring seemed to help.

Now I have to decide whether it is really worth all the effort to dig a deep hole and fix a mounting pole in concrete. I have had the galvanised pipe for weeks but still have the dish hanging temporarily on an angle iron trapezium.

Will a firm pole and the original mounting provide any extra signal? It would certainly ensure the dish didn't move. The large dish is extremely sensitive to pointing. The problem with poles is that they are fixed. You don't get a second chance to position it perfectly. There is a bank falling away behind the dish position with mature shrubs beyond. Which rather limits where the pole could go.

Access is still required behind the dish for adjustment. Though pushing the dish back as far as possible would be beneficial for other reasons: It takes up slightly less space in the parking area and looks slightly smaller with increased distance from the house.

Height is another important consideration. Cars can be parked closer to the dish since it will see over them better on a taller pole. While a taller pole exposes the dish to slightly stronger winds and provides less shelter from shrubs and hedges. Reaching the feed is more difficult but not unduly so from a stepladder. However, a taller pole increases the leverage the dish loads put on the pole in high winds. Better not to let the dish be exposed to high winds!

Tuesday: My new Invacom feedhorn has now been with DHL Germany for five whole days without moving! [According to their own Track and Trace web page] I paid extra for premium airmail too! Thank you DHL for falling over yourselves to get the item to me! You can look forwards to my negative comments on Trust Pilot.

Wednesday: DHL finally updates its T&T to say the package arrived in Denmark on Sunday, 3 days ago. Though it took them four days to update this information. Still no word whether it is out for delivery.

Now it seems the package might have been handled by Deutsche Post for delivery via Post Danmark but who knows? DHL's T&T web page can't even carry the tracking number over from German to English! A new search has to be made in the new language every time I hit the English button. Which means copying the tracking number to paste it into the new language search box! It is 2014 isn't it? Don't you believe it! No post, at all, again! 

I tried digging a pole hole in the ideal spot and found 50% hardcore and 50% half bricks. Two feet (60cm) further forward and I found just hard, compacted soil. I have reached about 24" so far but it is far too hot and humid to continue today. I shall start digging again tomorrow when it is cooler. There seems to be a layer of hard clay down there now. As long as I don't hit any rocks, cables or pipes it should go quite quickly. The hole still needs to be enlarged to take the welded pole flange. I didn't want to dig a large hole straight off in case I hit more hardcore.

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Matching the feedhorn to a faster dish III [Director's cut]

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So much for the plans of mice and men. It was late afternoon before I was able to work on the feed again. By which time, of course, there were no SB channels available.

The IRTE complicates the issue (considerably) by having a concave curve to the forward edges of the scalar rings. The Invacom which I was trying to emulate is flat across the face of the scalar rings. There is obviously more to feedhorn deign than throwing a few rings around the waveguide throat. The original Kathrein feedhorn has only one scalar ring and is supposed to be matched to the dish. Yet the (supposedly mismatched) IRTE bettered my brass copy [with the missing C120 LNB fixing added] by 2% points of Q.

First I switched the Fortec Star Passion HD receiver to Sky News on Astra 28E and checked the bare feedhorn S/Q @ 78/75% for a baseline. I refitted the ring and I instantly had 79/82% !! 7% points increase in Q is certainly worth having! What went so wrong yesterday?

Then began the task of turning the ring down to make it shorter to see what would happen. I started with a 5.5mm extension and reduced it to 4mm. 79/85%!! That's more like it! Then I reduced the extension to 3mm. S/Q dropped to 79/82%. Whoops! A bit too much!

I tried pulling the ring out a little to compensate but S/Q would not budge from 79/82%. Mind the gap!?!

So I was forced to turn another ring with more extension. This went very quickly this time because I had the old ring to measure. The throat dimensions were again matched to the IRTE feedhorn.

I made the extension too long expecting a much worse result: With a measured 5mm extension beyond the plastic cap I now had S/Q of 79/84%. Good enough! That's 9% points of Q over the bare feedhorn! I removed the new extension ring again to check. The bare feedhorn was still showing 78/75%. The new (5mm extension) ring is shown fitted to the IRTE feeedhorn above. The darker ring is just a reflection of the extension ring in the clear plastic cap.

I seem to have come full circle. Allowing for the thickness of the plastic cap the extension now matches the Invacom tuning literature at 5.5mm for 0.34 F/D. Should I shorten the ring slightly to try and get that 1% Q back again? I am now haunted by the thought that the plastic cap is insulating the extension ring when it ought to be earthed to the body of the feedhorn to form the entire waveguide from one lump of metal. I could always add the plastic cap to the extension ring if I knew what adhesive to use.

I tried other channels but still no UK Spot Beam on 28E at this time. [19.00pm CET] 

Will the considerable "improvement" in Q on Sky News spread itself across the UK SB when there is a signal tomorrow? Who knows until I try? Why were my results so poor yesterday after I fitted the extension ring? I have absolutely no idea at the moment! Was I using a different frequency yesterday? Is the ring altering the feed [LNB/feedhorn] frequency response? Read tomorrow's exciting episode! When it (probably) all goes horribly wrong again! ;)

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Tomorrow was cancelled. At least it was for the UK Spot Beam. Not one single channel showed a signal! I removed the ring thinking this was the cause but this had no effect. The Pan Euro beam was fine but with strange ups and downs in signal Quality. All depending on whether the extension ring was in place, or not. The presumption must be that the extension ring spoils the (supposedly flat) frequency response of the IRTE feedhorn. I have now ordered an Invacom ADF-120 feedhorn to see if it helps to get a better F/D match.I shall have to devise a clamp for the feedhorn neck to adapt it to the central feed boss.

Realigning the dish brought back Astra 28E UKSB for the usual short reception period around lunchtime. The feedhorn extension ring helped.

Now I have to decide whether it is worth the effort to dig a deep hole and fix a pole in concrete. I have the pole but I have the dish hanging temporarily on an angle iron trapezium. Will a firm pole and the original mounting provide any extra signal? It would certainly ensure the dish didn't move. The large dish is extremely sensitive to pointing. The problem with poles is that they are fixed. Access is still required behind the dish for adjustment. Though pushing the dish back as far as possible would be beneficial for other reasons: It takes up slightly less space in the parking area and looks slightly smaller with distance. Height is another important consideration.

Tuesday: My new Invacom feedhorn has now been with DHL Germany for five whole days without moving! [According to their own Track and Trace web page] I paid extra for premium airmail too! Thank you DHL for falling over yourselves to get the item to me! You can look forwards to my negative comments on Trust Pilot. Wednesday: DHL updates to its T&T say the package arrived in Denmark 3 days ago. Though it took them three days to update this information. Still no word whether it is out for delivery today

Wednesday: It seems the package might have been handled by Deutsche Post for delivery via Post Danmark but who knows? DHL's T&T  web page can't even carry the tracking number over from German to English! A new search has to be made in the new language every time I hit the English button. Which means saving the tracking number to paste it into the new box. It's 2014? Don't you believe it!

Click on any image for an enlargement.

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Matching the feedhorn to a faster dish II?

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Despite the rather negative summary above I was still mulling over the purchase of an Invacom adjustable feedhorn. This was really a last gasp chance to improve signal quality when almost all else had failed. While I was probably clutching at straws I wanted to be able to tick off the remaining possibilities. Otherwise I would never know if I had missed some obvious trick to extend 28E UKSB reception beyond the present paltry few hours.

The tubular throat pipe of the Invacom ADF-120 feedhorn is threaded to allow the matching scalar rings to be moved ahead of or behind the central throat. The more the protrusion of the throat, beyond the scalar rings, the wider the feedhorn "sees."

With a "fast" F/D ratio dish the feedhorn must be even more carefully matched than with "slower" parabolas. The feedhorn must "see" wide enough to capture the vital signal from the very edge of the dish. Where ironically by far the most dish area is situated. Otherwise the feedhorn has effectively reduced the diameter of the dish. If, however, the feedhorn is adjusted to see beyond the edge of the dish it picks up more noise. Which may be just as bad as a weaker but cleaner signal from the (effectively) smaller dish.

Here is the graph showing the required protrusion of the ADF-120 throat beyond the scalar rings. The F/D (Focal Ratio) of the dish is on the vertical axis.

The Kathrein 2.2m dish has an F-ratio of 0.34. [75/220cm] Carrying the 0.34 line across the ADF-120 graph to the falling curve suggests ~5.4mm protrusion. At least it does on the ADF-120. Will the F/D 0.38 IRTE feedhorn respond in exactly the same way?  The only way to find out is to try:


 There are two ways of extending the throat protrusion. The scalar rings could be cut back in the lathe. Or the waveguide throat can be extended with an add-on ring. The first is rather permanent if it fails and leaves the bare edges of the scalar rings open to corrosion unless painted. A press-on throat extension ring is a much simpler matter and has no permanent effect on the feedhorn.

So I made an aluminium extension ring in the lathe to fit on the central throat of the IRTE feedhorn. Making it fairly tight would ensure it would not fall off in its naturally downward facing condition. The situation was slightly complicated by the clear plastic cap on the feedhorn throat. This thin cap is intended to keep insects out. Particularly spiders which might fill the entire length of the waveguide feedhorn and LNB bore with cobwebs. I decided to leave the cap in place and made the bore of the ring the same as the IRTE feedhorn throat.

First I made the "socket" to fit nicely on the feedhorn throat cap. Then I gradually shortened the ring until I measured just over 5 mm to the face of the plastic cap from the front edge of the ring when in place. I turned the outside of the ring to match the diameter of the feedhorn throat.

Now all I need to do is test the modified feedhorn on a real signal. I doubt it will make a dramatic improvement in signal quality but it is easily adjusted for more overhang (protrusion) and instantly removable if it proves to be worthless.

And here is the extension in place on the feedhorn. The internal step at the ring/feedhorn interface is an illusion due to the plastic cap. The bores are carefully matched and fit closely together to avoid any gap.

So much for theory. The results of fitting the extension ring to the IRTE feedhorn were awful! Signal S/Q dropped instantly from 82/56% [bare] to 72/30%. [ring fitted] That was on the 28E Pan-Euro beam. Ouch!

There was the usual No Signal, with or without the extension ring, on the 28E UK Spot Beam after 14.00 pm. [Which was when I first switched on.]

The only hope for improvement, over the bare IRTE feedhorn, is to shorten the extension ring in small steps. Testing at each protrusion length until it has no extra extension left. The IRTE feedhorn has a slight protrusion of the throat pipe. I may have completely overdone things by making the ring extension far too deep/long. I had already turned a mandrel to hold the ring in the lathe so shortening it in (say) millimetre steps between testing will be easy enough.

I will have to wait until tomorrow to have a UK SB signal to test my shortening results. The difference between the F/D minimum of 0.38 (IRTE feedhorn) and the Kathrein dish's 0.34 will probably need only a tiny ring extension. Tomorrow will tell.

After further thought I realised that it is the extension beyond the front surface of the scalar rings which matters. I had used the plastic throat cap as my baseline. Where the IRTE feedhorn throat already has some protrusion. Next step is to cut the ring down in stages to 5.5mm above the scalar rings to match the [F/D 0.34] tuned Invacom.

Click on any image for an enlargement.

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Final Summary?

 )

Only a much larger dish at this geographical location will improve the signal. Moving the same dish to another geographical location might offer far greater benefits. I must presume that my dish is lying on, or close to, the null line which passes N-S through mid Denmark.

My own results suggest I am in much the same problem situation as my fellow TV fringe enthusiast. Who lives only a few miles away. He has exactly the same 2.2m dish and enjoys(?) very similar reception only over a limited time of the day. Though again with the same slight  but unreliable variations at odd hours on odd days as I have myself experienced.

Such is the narrowness of the signal acceptance angle on a large dish that it may not be able to receive both 2E and 2F at the same time. The spread between the two transmitting satellites places them either side of optimum axial gain at the focus of the dish. One, or the other, or both satellites become effectively offset. Just as if the dish were poorly aligned.

The Astra 2E/F UK Spot Beam has succeeded in denying an adequate signal even to those fringe TV enthusiasts willing to invest a huge amount of time (and potentially a great deal of money) just to receive the same UK programmes as before. It was once relatively easy to receive UK TV from the previous Astra 2D also at 28E. Often with only slightly oversize dishes and some care in set-up. I myself had perfect reception around the clock in all weathers from a 120cm Gilbertini offset dish.

Many would consider even this a very large dish for many domestic situations. With the recent change in satellites I first tried a 1.8m (6') dish and now the relatively huge Kathrein 2.2m dish at 7'4") Still without more than partial and very time restricted reception around late morning until just after lunch. Exactly when the UK TV channels are full of absolute dross. The evenings being the best chance of any programme quality (at all) are now denied to myself and many others.

The denial of a 'home' TV service to so many British ex-pats has largely succeeded. The TV companies can continue to maximise their income from their license-subsidised production empires. Simply by selling to strictly limited, geographically-organised, commercial cable and retransmission scrambled satellite services. To sell the programmes onto their already jaded viewers sandwiched between their own commercials for further profit. And all, at greatly increased levels of irritation and expense to the end consumer.

Or the film producers can drive yet more potential viewers elsewhere. To obtain their entertainment by other means than satellite TV. The Internet has become the entertainment medium of choice for many. Sadly there is still no fast, universal optical fibre service over much of Europe.  So streaming films in HD is difficult to impossible due to a lack of bandwidth. I have a 50/50Mps service but have never tried to stream a film. Just getting a decent HD video experience from YouTube can often be a struggle!

No doubt the pirates and conmen will profit enormously from the changes in UK satellite TV reception in Europe. Where there is a market somebody will always step forward to supply it. UK TV denial could be looked at as a form of prohibition and we all know what happened then!

DVDs and Bluray disks continue to decline in sales as Hollywood continues their downward decline into totally absurd, drug, money and celeb fuelled, mediocrity. Their products selling at outrageous profit per sales unit. With unduly restrictive legal barriers to the re-use of something already purchased and presumably owned. We truly live in an era of false accounting and virtually total lack of real creativity. Monopolies rule by playing with monopoly money at the expense of the poor consumer.

My own UK TV journey has finally come to an end. There is nothing left other than the huge investment in one, or even two, very much larger dishes. Nothing less will squeeze enough out of the present, deliberately weakened signal to make watching UK satellite TV worthwhile. The cost alone makes this quite impossible. Having even larger dishes in our rural garden would increase the risk from the increasingly vicious storms due to global warming. The loss of visual amenity in housing such vast structures, in what is supposed to be a normal garden, makes it even less desirable! 

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UK TV RIP!

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I have obtained a TV which I could read at some distance in bright sunlight. It was propped up in the shade of my car boot with the Fortec Star Passion HD receiver alongside. After initial tests with a twin coax video/sound cable I swapped to a short HDMI betwen the two. The picture was easily bright and sharp enough to read from the dish at some distance. I set the receiver menu to Signal Strength and Quality display. While the readings might not be scientifically accurate they are easily repeatable within the same system. No more is required for testing purposes.

First I confirmed that the Kathrein 2.2m dish was indeed aligned perfectly on 28E UKSB as tightly as possible. No movement of the dish (in any direction) increased the Signal or Quality. In fact the readings fell. So there was no more to be had here. The wind was light enough to be having no effect.

I could then move on to maximising LNB focus and skew. The brass feedhorn was already set at the calculated focal distance of 75cm. I peered through the small hole in the middle of the dish to ensure the feedhorn was centred and pointing straight at the centre of the dish. No change in Strength or Quality was noted with increased accuracy of alignment.

Quality dropped with all changes in feedhorn focusing so I left that alone too. Skew was fairly insensitive but I found the mid point of the angular limits and tightened the LNB clamping screws. 

I then noted the signal Strength and Quality readings on the screen and removed the home-made brass feedhorn to fit the cast alloy IRTE. Quality immediately increased by 2%. So the IRTE (despite a slight theoretical F/D mismatch) was obviously the better choice. I tried changing the focus and skew with the IRTE but they remained best at the same, brass feedhorn settings.

The HD100 cable had softened slightly in the unusual 76F heat and bright sunshine. So I stretched it out as straight as possible. Though this had no visible effect on the signal readings there is a theoretical chance of signal being lost with too many tight turns at such high frequencies. No point in leaving anything to doubt.

The Inverto Black Pro C120 LNB is highly thought of on the satellite forums. Unless I have been unlucky and received a poor example there is not likely to be any serious improvement by fitting any other LNB.

The IRTE feedhorn could be swapped for an Invacom Universal. Whether this would be worth the extra expense is difficult to say. The gain is likely to be only very marginal. 

The Fortec Star Passion HD receiver fails to lock below about 53% signal Quality. I have tried a borrowed Kathrein receiver and found it almost the same for sensitivity and ability to lock onto weak signals. There may be slight gains to be had from a change of receiver but I doubt it would be worth the expense of actually importing one.

Which only leaves the Kathrein 2.2m dish. Though old, it is a professional quality, spun aluminium dish in undamaged condition. Unlike some plastic dishes with embedded, open mesh reflectors the solid aluminium dish cannot lose signal by changing between C and Ku band. Thanks to its rear, skeleton reinforcing frame the Kathrein is unlikely to lose its shape. So it should have retained the surface accuracy with which it was originally made.

I recorded my maximum signal levels across the range of UK TV channels and transponders between 13.00 and 13.15pm. By 14.00 signal quality had already dropped by around 5% in many cases. While signal Strength had strangely increased by 2-3%. No changes were made to the system when 14.15pm marked the local death of most of the BBC channels. With many of the ITV channels falling out at 14.30pm. Only a few stragglers remained with solid reception until I finally lost patience with hiccuping sound and lack of pictures at 14.45pm.

)

Recabling.

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I have just obtained some very high quality Webro HD100 coaxial cable from a fellow fringe reception enthusiast.

The idea was to test the effect of brand new, copper shielded cable against (at least a decade old and supposedly ageing) aluminium shielded cable of roughly the same overall length.

Originally, I was using two long lengths of the old, white, coax cable. With a straight connector joining them in the middle to reach the Kathrein dish behind the house.

Only half the length is usually required at the usual dish site in front of the house. No DiSEqC switch was involved in either test case. 

I am (almost) afraid to report that swapping the old, series connected pair for a single run of 33 metres copper shielded HD100, with freshly fitted plugs on bright metal, had absolutely no effect whatsoever. None at all.

NO discernible change in measured signal level, quality or reception. 

Why does this remind me of HiFi cables and snake oil? :-))

The Webro is black and much stiffer than the old, white, aluminium-screened coax.

 I borrowed this spec list and image for the HD100 from an eBay vendor:

- CLASS A+ COMPLIANT
- TRI SCREENED
- SOLID FOAM DIELECTRIC
- SOLID COPPER CONDUCTOR
- CAI APPROVED
- ROHS COMPLIANT
- LSNH TO: IEC 61034-1, IEC 60332-1, IEC 60332-3 CAT C, IEC 754-1

Physical Characterises:-

Conductor: CU 1.0 +/- 0.02mm
Dialectic Thickness: 1.81mm
Dialectic Material: Gas injected physical foam
Dialectic Diameter: 4.65 +/- 0.15MM
Dialectic Colour: Natural
1st Foil: CU 115%
Braid: CU 0.12+/-0.008x 16x5
Braid coverage: 55%
2nd Foil: AL-PET 115%
Sheath thickness: 0.66mm
Sheath: LSNH
Overall Diameter: 6.70 +/- 0.15
CAI Approval number: CAI 0068 A

Electrical Characteristics:-

Rated Voltage: 30V
Capacitance: 75
470 – 1000 MHz: >75
1000 – 2150 MHz: >65

Next day testing had BBC channels dying by 3.30pm with most ITV, Channels 4, 5, etc. hiccuping and unwatchable beyond 15.45pm.  I checked the length of my pair of series white coax cables and they were about 20 meters (max) altogether. So the HD100 has a 13 metre disadvantage but no straight connector in the middle. It probably balances out. I was careful to unravel the coils of the HD100 where they had come off the drum. I didn't want to undermine its performance by having too many tight bends.  

Today I fixed some cords to the top, bottom left and right  to the skeleton frame of the dish. I could then sit comfortably at my tiny TV and make small adjustment to the dish pointing like a puppet master. Sadly this had no beneficial effect at all. The dish was at its best with the ropes relaxed.

The only changes I haven't tried  yet (while monitoring the signal Quality) are skew and focus adjustments. On the tiny CRT TV the figures are simply too small and fuzzy to read easily in bright light with any accuracy. So ideally I need a better monitor for testing these parameters. It's a shame one can't use redundant computer monitors but they only work on serial cables.

)

Rain fade!!!

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Another attempt to fine tune the dish in pouring rain! All Spot Beam channels available at 11am CET. There seemed to be no match between the sheer weight of the rain falling on the car and signal drop-out. I had the doors tightly shut with both receivers taking it in turns on the passenger seat. The tiny CRT TV offers a picture too small (and fuzzy) to be certain of the S&Q readings. I brought out the car sunscreens to hide the reflected glare from the 2.2 metre dish behind me. Then I found something tall enough to prop the TV up where I could see it more easily without annoying reflections. You would not believe the hours I have wasted peering at this 4" TV over the years while dish aligning. When a small flat screen TV would have helped enormously.

Then it occurred to me that I could use the drop-out glitches to fine tune the disk pointing further. Except that it would not stop pouring down! Every time I determined to get out of the car to fiddle with the dish the rain would redouble its efforts! During one brief pause, in still steady rain, I looped a chord between the edge of the dish and the angle iron stand. Then I wound a stick through it to allow me fine aziumuth adjustment. (tourniquet style) This did not help. I could neither see nor hear the TV in the car through the pouring rain. Returning to the car to watch a channel or flick round the signal would soon go off again.

Relative dish size from 1.2m up to 3m.

It was all getting a bit silly and OCD by now. So I used an easing in the rain to escape indoors to gather my thoughts in more wasted blogging electrons. There is now a big puddle outside the car door where I have been getting in and out. I may have to move the car without damaging the cables snaking across the parking area.

I imagine the rain and rain-bearing clouds up in the sky have far more effect than what is falling locally. This would explain the mismatch between signal strength and falling rain. I had solid reception during the heaviest rain. Only for the signal to fade when the rain eased off again. The rain stopped briefly but I had no signal on several transponders which were fine only moments before. I obviously still have far too little overhead on the signal strength and quality to ensure a reliable reception lock on the receivers. The difference in signal level between all the different channels is quite ridiculous! Worst, by far, is ITV2+1.

As I sit here scribbling away the sun has come out and it has finally stopped raining. Is it just trying to tease me into trying again? Off we go again!

By now many channels had dropped out with only ITV3 & 4 still just watchable.  

13.15 and there were no Spot Beam channels left at all.  I don't think there is much of a margin left to tweak with. Millimetre movements of the edge of the dish do make a difference. Though only when there is a signal to play with.

Is it worth all the effort to dig a huge hole and cast a steel pole in solid concrete? I am really not sure at this moment.  Yes it will give me a stable base and allow much finer adjustment but for how many hours of TV per day? Most UK daytime programming is absolutely unforgivable dross! With very rare exceptions like cycle racing.

14.15 Switched on again to check the latest situation. Many of the UK SB channels were now watchable! It is windier than earlier but much brighter. With the heavy clouds clearing to blue sky in the south.

Will continue to monitor at intervals this afternoon.  BTW: No DiSEqC switch is being used now. Just 20 metres of coax with a straight coupler in the middle. Using the Fortec Star Passion HD receiver. I am now informed that the coupler causes a 2dB signal loss. Whoops! That is much the same as reducing dish size by a foot or more in terms of signal gain!

15.15 No check.

16.15 Still some channels watchable. Mostly ITV with only one BBC channel locking at intervals.

17.15 Not one UK SB channel receivable now.

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[P22] Testing-testing.

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Due to other chores I only had the system set up by 14.30pm again. Getting the dish pointed correctly from the new position was rather more difficult than anticipated. Despite having a decent compass I seemed to have found the wrong satellite again. I checked the dish's altitude while listening to the SatFinder meter's irritating whistle. It should whistle on zero gain if it is 28E.

Only when I moved the dish by a large angle in azimuth was I finally able to pick up 28E. Then there was more "fine" dish movements before I could get the UK Spot Beam. Certain transponders were stronger than others. It was now 15.00. BBC channels were again weaker than ITV. Channel 4 was variable between channels. (Presumably broadcast on different transponders.)

As the signals began to fade at 15.30 I tried swapping receivers with a Kathrein which was kindly loaned to me for comparison. I cannot be sure but I think the Fortec Star Passion HD is just marginally better at locking onto fringe signals. Though I really could not be certain I was comparing like with like. The channel lists were so different with lots of duplicates on both receivers. No scientific accuracy is claimed nor meant by anything you will read here.

By 16.00pm there were only  a few Spot Beam channels still working. Most of the others registered no signal or nothing at all. A couple of ITV channels hung on longer than the rest but hiccuped and froze at times. I gave up at 4.30pm with only Pan Euro beam channels left. It seems the new dish and turned brass feedhorn are not gaining enough to extend reception by much over the Salora 1.8m. But again I cannot be certain that present conditions are the same as before. It was raining almost continuously again today from a solid overcast. "Rain fade" is well known in fringe reception conditions. All a far cry from previously perfect  reception on a 120cm dish under all conditions on 28D year round.

I know from my early experience with the 6' Salora dish that fine azimuth adjustment is absolutely vital to fringe reception. A quarter of a turn on the Salora mounting's azimuth adjustment screws was the difference between receiving the UK Spot Beam channels or nothing at all. At the moment I am literally dragging the slotted angle stand around on the wet lawn to rotate the 2.2m Kathrein dish.

Fine adjustment is not remotely what I would call it. So the potential exists for far better fine tuning in azimuth. I already have fine vertical adjustment in altitude. Due to the flexibility of the slotted angle stand I can flex the dish from side to side and rock it up and down. My wife tells me the dish was fluttering quite noticeably in the wind the other day.

There are now two ridiculously large dishes set up in my garden as well as several smaller ones. Still with no more than marginal UK TV reception over a very limited period each day. One must assume that I am living close to the supposed null line. Which is theorised to run north-south over the middle of Denmark. Though the exact location is still open to rumour due to the lack of feedback by other big dish abusers. Some people even imagine that a positive report online will result in the satellite company tweaking their beam pattern to spoil the fun.

It is certainly odd that the many ex-patriots, who are not resident in the UK, have lost their national TV service. Enjoying their home TV was the unbreakable anchor chain which kept them feeling at home. Wherever they happened to be living at the time. Many enjoy their annual holidays on the Continent and have paid their TV license in full. The advancing tide of copyright greed has spoilt it for countless ordinary people living or holidaying "abroad".

So much for the pretence of equality and equal rights within the EU. Gutless and riddled with corruption from top to bottom! Except when the bananas need to be straight. Don't forget to vote in the present EU elections! A banana near you may need the help of the endless gravy train riders to the life of endless luxury, blatant fraud and countless wasted opportunities to reform.    

My own investment so far has not been financially crippling thanks to purchasing both dishes at favourable secondhand prices. [Complete with their respective altaz mountings.] It might still be possible to sell both of them to fellow fringe reception enthusiasts in less demanding areas of Denmark. But only if I completely lose patience with the poor reception so far. I could turn the dishes into giant bird baths complete with fountains, garden ponds (again with fountains) or even domed roofs for small, round, decorative garden sheds. Aluminium is toxic to some wildlife so the Kathrein won't make an ideal fish pond.

The Kathrein 2.2m prime focus dish beside the now redundant offset 1.2 Gilbertini. The Salora 1.8m dish lies between the two in size and is indicated to scale by the shaded circle. [From left to right: 4', 6' and 7'4" in  old money]

Those who consider a 1.2 metre grey dish as too large for their garden have absolutely no concept of how a white one, almost twice the size, looks from the front! From the side and rear they look much less significant. Being round they are not traditional rural furniture in appearance. A caravan is absolutely huge in comparison but nobody gives a caravan a second look. Not even a snow white one. A round white dish can be spotted from a great distance!

Luckily the larger dish is now behind the house out of sight. (For the moment.) The smaller, Salora might as well be taken down now. I wonder if the dishes will show up on this year's free, aerial imagery and mapping service provided by the Fyn Councils? Perhaps I should cover the big one with a green tarpaulin tent in case people imagine they are seeing UFOs! Fortunately Google Earth imagery of Denmark is often so absurdly poor and so many years out of date, that nobody will ever notice anything unusual!

)

[P21] A matching feedhorn in brass.

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I was worried about the potential mismatch of the IRTE feedhorn with the faster Kathrein dish. So I decided to turn a matching feedhorn from a lump of scrap brass.

I was afraid that I was not illuminating the entire dish when using the IRTE feedhorn. This would have the same effect as using a smaller dish.   

Buying an Invacom feedhorn from the UK would be foolishly  expensive by the time P&P was added. A German dealer is much cheaper but is currently closed for a holiday.

So I have copied the original Kathrein feedhorn throat dimensions in brass. I will make the rear end longer to fit the new feed boss which I purchased for the Salora. I shall be copying the two IRTE feedhorn flanges at the rear. This will allow me to clamp the LNB to the feedhorn and to use the IRTE skew clamping ring.

The image above shows early progress with the feedhorn end just roughed out on the end of a 100mm long x 55mm Ø bar.  A time consuming task in hard brass using plunge, face cuts. I just put the lathe in back gear and engaged the longitudinal feed to cut down on chatter. The outside diameter of the single scalar ring is 50mm. Inside diameter 44mm. The waveguide bore is 19mm right through. (As is the LNB) Guided by the cast IRTE feedhorn I decided to made the throat tube slightly too thick. Though I doubt it makes much difference. I can always make it thinner if I discover this is an important factor.

The brass feedhorn is now finished. Shown with the Kathrein and IRTE feedhorns and prime focus boss.

The brass feedhorn is resting on the adjustable skew, clamping ring.

The boss is difficult to fit onto the feedhorn unless the groove just behind the feedhorn throat is made wide enough. The bent ears catch in the sides of the groove.  No problem on the IRTE. Where there is a large space and small neck behind the feedhorn.

I had to cut the original groove much wider. It was lucky I had not removed the feedhorn from the lathe chuck before I checked that the boss would fit. So removing the boss from the dish in the pouring rain (for the umpteenth time) was not a wasted effort.   

The new feedhorn now clamped to the triangular, IRTE, prime focus feed boss.

I was delayed for hours by the lack of proper indexing on the Inverto LNB clamping holes.

No four holes match any other four as the LNB is rotated relative to the feedhorn! I had indexed them correctly and then had to file the original holes oval to allow the screws to fit the LNB's spacing!

Another problem was to maintain concentricity of the LNB with the feedhorn bore. Any mismatch will cause an eccentric step in the waveguide. Hardly desirable given the care I took in making the brass feedhorn.

Another view of the Inverto Black Pro C120 prime focus LNB attached to the new brass feedhorn and IRTE boss.

I just hope it helps to drag a few more dB out of the bigger dish. 

I still don't know why Inverto use such a weird shape for the body just above the F-plug thread. It is impossible to fit a rubber boot!

I will probably have to fit a rain shield just above the LNB.





I wish I could report that the new feedhorn worked miracles. But alas no. It was 14.30pm [CET] by the time I was set up and ready to test reception. Then it started raining harder than ever. I sat in the car flicking around the channels on 28E with the remote. The receiver and TV were sitting on the passengers seat and the doors shut to keep the rain out. Pan European beam: Solid reception. Spot beam? Nothing. Not one channel!

When it finally stopped raining (briefly) I checked the feedhorn was set at the correct focal distance. [75cm] Then I taped a small round make-up mirror to the face of the new feedhorn and squinted though the peep-hole in the centre of the Kathrein dish. The feedhorn was way off from aiming at the centre of the dish. Lots of adjustments later I had the reflection of the peep-hole centred in the mirror. I then rotated the feedhorn to ensure the mirror was square to the feedhorn. It wasn't! Grrr! Trying to free the thin mirror from its plastic case would probably break it. So I did not try.

By moving the trailer from its usual parking place I was finally able to move the dish backwards by just over two metres. This should give me a clearer view over the tall hedge without resorting to loppers and high ladders in the pouring rain.

Tomorrow promises yet more showers but I shall persist at a much earlier time in the hope of pinning down the Spot Beam channels while they are still strong enough to get the dish properly aligned. Then I can try swapping feedhorns [with the IRTE] to see if either of them is superior to the other.  

Click on any image for an enlargement.

)

[P20] Another hurdle to overcome!

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It often happens that an obstacle presents itself in front of our satellite dish. A roof, hedge, wall or a tree are the usual examples. The entire surface of the dish must see clear sky in the direction of the desired satellite. (assuming for the moment that the dish is fixed and only one LNB is fitted) Luckily each TV satellite sits almost perfectly still in the sky as seen from the ground. It doesn't matter if there are mountains or skyscrapers blocking your view in every other direction. All that matters is that the dish can see the required satellite without obstruction.  

By a happy coincidence Astra2 at 28E has a local altitude of almost exactly 25 degrees for my site. 25 degrees is a handy altitude angle to have. Because you can divide the distance to the object by two to get the allowed height of that obstacle. Well, near enough. Tan 25 = 0.46 rather than 0.5.  So halving the distance to check the allowable hurdle height is slightly too generous. Tan 27 degrees is nearer to a true half. So for 25 degrees satellite altitude I should really use 0.46 x distance to the potential signal blocker. Not quite so liberal as using a half x distance if it is really critical.

The simplest way to check whether the dish is seeing the satellite without any blockage is to draw a line on a piece of paper at the local altitude angle of your intended satellite.  Now mark centimetres along the bottom and draw vertical lines from your marks. Measuring up to the sloping line at any given distance point will give you the allowed height of any obstacle in the signal path to your dish. You can use the markings for any scale that suits you. Just remember to use exactly the same scale for height up to the sloping (altitude angle) line as your horizontal markers.

And, don't try and mix your units! Professionals have built bridges which did not meet in the middle because they mixed their metric units on one side with their imperial measurements on the other! No doubt the same problem has occurred with tunnels where two nation's contractors mixed their different units of measurement.

The bottom of the dish is the critical point from which to check that it can see the satellite without obstruction. It is here that any "shadow" on the signal path will be most likely to occur. Particularly with large dishes. Fortunately, many dishes are a mounted a certain distance above the ground. The height from the ground to the bottom rim can be added to the allowed height of the obstacle.

A simple example using my own site: Taking 25 degrees as the satellite's local  altitude I measure 5 metres to the hedge in front of my dish. Halving this figure gives me 2.5 metres allowed height. [Actually 2.4m] But the lower rim of my dish is a metre above level ground. So I can have a hedge 3.5 metres maximum height in front of my dish at 5 metres distance. Any higher than this and the hedge will block some signal arriving at my dish. Which would be very undesirable for fringe reception where every dB of clean signal is vital.

My own front hedge is 3 metres high and looks taller. From the dish it looks as if it might well block the signal from reaching the bottom of the dish. Those new spring shoots will have to be clipped back very soon! Raising the dish is another possibility but rarely practical.

Now I know that I must have the bottom of my 2.2m dish at least a metre from the ground too. Or I will need a lower hedge. Which would not offer the same degree of shelter from the prevailing wind.Though I suppose I could cut a lower step or notch out of the hedge in front of the dish in the direction of the satellite. Though this might make the dish far more obvious to observers beyond the hedge. Each situation is different, of course, but what the neighbours can't see won't hurt them.

Hedges can be measured with a long stick or pole and then the stick itself measured when it is lying flat. Insulating tape can be applied as a marker if the stick is much longer than the obstacle is tall. Then stand the stick up again and check from a reasonable distance that the tape coincides with the top of the obstacle. Now measure the stick or pole from the bottom up to the insulating tape to find the correct height. Much easier than trying to force a floppy tape measure to stand upright! Snake charmers excluded, of course.

Conversely, you can mark a pole at the correct allowable height for a known distance measured from the dish. Then stand the pole up using something like a stepladder or braces for support. Now use a small mirror at the bottom of the dish to check that the reflection of the hurdle beyond the pole marker is lower. Or you can grovel on the ground with your eye at the level of the bottom of the dish if you prefer.

If the hurdle is lower than your marker on your pole then the bottom of the dish is not in the signal shadow of the hurdle. If it is quite close to the marker and the hurdle can grow then clip the hurdle or move the dish. Hedges and trees have a nasty habit of growing faster than you would ever believe! So siting a dish with a fast growing hurdle in line with the satellite will almost certainly end in tears. With no useful signal sooner than you think! How much concrete did you put around your dish's support pipe? Well now you have to do it all over again with a new pipe. Or buy an expensive ground stand to allow some mobility.

If you can't use a measuring pole or stick because of the landscape in front of the dish or the dish is high on a building then life is rather more difficult. Taller and more distant objects are much more difficult to measure without a stick or measuring pole. Not everybody owns a clinometer but you can measure your own shadow on the ground. (or that of a stick) Then measure the length of the tree's shadow straight afterwards. Leave it too long and the sun's own altitude angle will have changed. Giving your calculation an inaccurate result.

Knowing the ratio of your own height to the length of your shadow you can use the same ratio to calculate the height of the tree (or other obstacle) from its shadow. The same goes for a building. This simple trick needs sunshine of course and is much easier with a reasonable solar altitude. It probably won't work well at noon at the equator nor at the Poles.

You can also use a known object in a photograph taken from some distance to measure an obstacle at the same distance in the same picture. Measure the object size in the image and then the obstacle itself. Use ratios again to determine the true height of the obstacle. Once you know the height of the object you can use a map to measure the distance between your dish and the distant object. There are measuring tools on Google Earth which can be very useful. Now add any extra height of the dish compared with the distant hurdle to your allowable hurdle height at that distance.

There are other methods to check whether obstacles will block your signal but I have already talked the subject to death. You could check which two days of the year the sun is at the satellite's altitude. Though it might be quite difficult to find this out in the exact direction of the satellite. There are plenty of free solar altitude calculators online. The problem is using them to find when the sun is at the correct altitude at the satellite's correct azimuth for your location.  

If an obstacle casts a shadow on your dish then something must be done about it. Owners of buildings, hedges and trees are highly unlikely to be sympathetic to your satellite reception needs. All you can do is raise the dish, move it back from the obstacle, remove the obstacle (if you can) or move to another location. All these possibilities have potential domestic, neighbourly, physical, visual and technical  limitations as well as almost inevitable expense.  

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