Best Way to Receive Whole Ku Arc With Fixed Dishes?

[pendragon]

After re-reading above, I am still a little confused about exactly where to point the lnbf on the dish surface.

I understand the string from the top of the dish and the bottom of the dish, top being 72.57" long and from the bottom being 43.56" long when drawn away from the dish.

I am still not sure exactly where to point it.

Would you mind using your graph above to draw a line where to point the LNBF?

Thanks again for your trouble!!

No problem, I guess my description was as hard to read as it was to write; sorry, I didn't mean to make it that way. I hope the attached diagram clarifies what I was trying to say. If there's anything that doesn't make sense, please let me know.

Note added after original posting: It's good that you made me draw a diagram of the feed pointing. It was immediately apparent that the direction I had it pointed did not properly split the angle subtended by the dish. I found a sign error in my calculations that seems to make it look much better. I've uploaded a new chart. Interestingly enough the spacing on the "string" corresponds now very closely to the Prodelin diagram's measurements and the calculations I made from it. The distance from the focal point to the dish is also very close to what you measured, but the center mark on the dish you noted appears to be bogus.

I will also correct my previous post in a moment. Thanks!

 

[pendragon]

In reference to pointing the feed, a few remarks should be made. The idealized pointing of the LNBF is based on illuminating the entire dish by a feed with infinite cutoff by the feed at the dish edges. Clearly this doesn't happen in real life.

If the feed pattern cannot fully illuminate the dish, it won't be that critical where it is pointed, so long as the pattern doesn't spill over the edges. On the other hand if the feed illuminates more than the dish, you would be better off pointing it on the high side (more toward the top) so the lower edge of the dish shadows the warmer earth from the feed. A little spill on the top isn't as problematic because the atmosphere/space is much colder. A Rx/Tx feed would be pointed at the point I indicated because you want as much power as possible to illuminate the dish. A RO feed represents a different compromise because you want to maximize the CNR rather than the signal power. That's why radio astronomy tends to favor deep dishes.

A lot depends on the feed. The f/D for this dish is about 0.6, so a feed designed for that should be a good match.

 

[Anole]

Thanks for the enhanced chart.
Some of us were discussing the problem earlier, and I think between what we figured out and your new picture, it's all becoming clear. - :up
And, it's good to see confirmation as to aim, LNB location, and focal length.
Thanks a bunch.

. . . now if I could just find one of these dishes . . .

 

[linuxman]

Thank you very much!!!

You have simplified everything to the place where even I can now understand it.

We'll make this dish a barn burner for signal.

Good Luck to Anole in finding one of these babies.

 

[linuxman]

I have been waiting on better weather, and the Geosat Pro SL2 LNBFs to arrive from SatelliteaAV.

The weather was good on Saturday and Sunday. Saturday it was 52, sunny, and no wind. Unfortunately there was still about 3 inches of wet and melting snow still on the ground. Not very conducive to setting up and tuning the Prodelin at least for me.

But today the 24 - LNBFs arrived along with dual and single clamps from SatelliteAV, so I can continue building inside. Supposed to be in the 50s Friday through Sunday, and by then the snow will be gone.

I will use the dual clamps on my Primestar dishes along with some singles when the Prodelin is finished.

I have started the assembly of the round conduit and have one SL2 mounted already. I am making my base clamps out of the ground clamps I mentioned above. As you can see they are going to work very well with the black clamps I ordered.

I am also thrilled that the SL2 has an extra 1/4 inch of movement area towards and away from the dish than the SL1 that I had pictured before.

Here are pics of the progress and a pic of the SL2s and clamps:

 

[Anole]

hog!

Geez, did you buy him out? -
Hope he's got some left.

Well, I must say, those LNB holders mate up -so- well with your ground clamps!
Far better than I expected.
Very professional looking, too!
In fact, I think maybe you've talked me out of using conduit hanger brackets on my next LNB. -

Let me know if you need more numbers for spacing.
Ya probably have enough for now to get a feel for things.
Kinda thinking how those calculations might be better automated . . .

 

[Keith Brannen]

The weather was good on Saturday and Sunday. Saturday it was 52, sunny, and no wind. Unfortunately there was still about 3 inches of wet and melting snow still on the ground. Not very conducive to setting up and tuning the Prodelin at least for me.

Now, if you had said you had 3 FEET of snow on the ground, I might have had some sympathy for you! But 3 INCHES! Sheesh, I wish! We just had a mini-melt and there is still at least two feet of the junk there (not including the massive snow banks from shovelling), and we are getting more as I type!

Anyhow, looks like you've hit the right combination of bracket/clamps/LNB holders, looking forward to the setting up and peaking of the LNBs and what signal levels you get (especially the outside LNBs).

 

[linuxman]

Now, if you had said you had 3 FEET of snow on the ground, I might have had some sympathy for you! But 3 INCHES! Sheesh, I wish! We just had a mini-melt and there is still at least two feet of the junk there (not including the massive snow banks from shovelling), and we are getting more as I type!

Well I hesitated even mentioning the snow knowing you guys in the frozen North were much worse off than we are and just let it go with "too cold for me", but I didn't and I do feel for you guys with way too much "winter". I am ready for spring myself and can hardly wait for better weather.

Anyhow, looks like you've hit the right combination of bracket/clamps/LNB holders, looking forward to the setting up and peaking of the LNBs and what signal levels you get (especially the outside LNBs).

I think the combination of what I have will be very versatile with lots of room for variation of angles etc.

I am hoping that might give me an edge on the outside signal levels.

Hopefully we'll soon find out.

 

[Keith Brannen]

Well I hesitated even mentioning the snow knowing you guys in the frozen North were much worse off than we are and just let it go with "too cold for me", but I didn't and I do feel for you guys with way too much "winter". I am ready for spring myself and can hardly wait for better weather.

I've been ready for spring since early December!

 

[Wescopc]

This is getting exciting with the SL2's, I have installed two Glorystar systems using them - they work great!
Bob

 

[linuxman]

Well I managed to get outside today and start re-assembling the support arm, rod, and LNBFs.

I couldn't make the arm and center lnbf confirm to Pendragon's diagram above.

I got 72 inches from the top and 43 inches from the bottom out to the center LNB. I put the support arm on with the square as instructed in the manual, and raised the platform out at the end to make it line up with the support arm.

Put the laser level on it, and it pointed to abut 44 inches down from the top on the tape which put the laser about 4 inches below the "circle". See the pics below.

The only way to make it point lower is to either lower the two bolts on the support platform, or tilt the lnbf down in front, which I tried, but it just didn't look true to the world. I could tilt the platform forward and get a little more down on the dish, but that doesn't appeal to me either.

Adjusted the dish up and down for the new location of the LNBF, and started some trials.

I have 91W 12050 V at 99% again, Macy's on 93W at 90%, and ABC News on 89W at 75%. 101W has 3ABN booming in at 99% and the old KUIL at about 30%. I am totally happy with 101W.

101W was acting just like 83W until I put a longer bolt on it and raised it up.

Tried 83W and got the RTN feeds at a watchable signal and will be better with a longer bolt. See pic of 83W pointing at the top of the dish. It will be better with the proper bolt and pointed at the center of the dish.

Couldn't get a smell of 79W today. I did some measurements, and need to shift the platform a little on the support arm to make both sides measure the same distance away from the dish. I also may need a little side to side adjustment of the dish with the new position of the center lnbf. I didn't do that today.

One of the downfalls of assembly inside and then attaching outside.

I hope to get some more time on it tomorrow. The weather will be nice the next two days, but have some things I have to do tomorrow that will take up some of my tuning time.

I also mis-counted and need to add another LNBF on the East side.

I think I am going to be very happy with this dish once it is all tuned in.

BTW, the Geosat Pro SL2 LNBFs are working fabulously! Great signal and very stable.

Take a look at the pictures below. The last picture is after tuning in. The rest are as I took it out from the bench.

 

[english2fourth]

prefer my motorized

i went a different path when i got the 1.8 prodelin. i mounted c, and motorized my 75c channelmaster. i get more than the span in the last picture with my motorized with excellent levels. but, i do have to wait. 129 to 91 is a long wait! but, one dish, it moves, looks cool, and i'm happy. the c looks cool, and it pulls C! kudos to the mods for this project, it looks excellent!

 

[Keith Brannen]

I have 91W 12050 V at 99% again, Macy's on 93W at 90%, and ABC News on 89W at 75%. 101W has 3ABN booming in at 99% and the old KUIL at about 30%. I am totally happy with 101W.

101W was acting just like 83W until I put a longer bolt on it and raised it up.

Tried 83W and got the RTN feeds at a watchable signal and will be better with a longer bolt. See pic of 83W pointing at the top of the dish. It will be better with the proper bolt and pointed at the center of the dish.

Couldn't get a smell of 79W today. I did some measurements, and need to shift the platform a little on the support arm to make both sides measure the same distance away from the dish. I also may need a little side to side adjustment of the dish with the new position of the center lnbf. I didn't do that today.

Looks very good. KUIL seems a little low, but I have seen their signal fluctuate quite a bit in the past (but then I do have it 8 degrees off-centre on a 60e dish, which would be more sensitive to minor signal fluctuations). Could be it was at a low level when you where setting it up, or it just needs a minor adjustment (after all, this was just a test day, not a "that's all there is" adjustment).

 

[pendragon]

I couldn't make the arm and center lnbf confirm to Pendragon's diagram above.

I got 72 inches from the top and 43 inches from the bottom out to the center LNB. I put the support arm on with the square as instructed in the manual, and raised the platform out at the end to make it line up with the support arm.

Put the laser level on it, and it pointed to abut 44 inches down from the top on the tape which put the laser about 4 inches below the "circle". See the pics below.

The only way to make it point lower is to either lower the two bolts on the support platform, or tilt the lnbf down in front, which I tried, but it just didn't look true to the world. I could tilt the platform forward and get a little more down on the dish, but that doesn't appeal to me either.

It sounds like you are about 0.5" too close to top and bottom for the center LNBF, assuming the dish geometry you measured and I calculated is accurate. Figuring out what those actually are will place the true focal point. Where the LNBF points may not be as critical, unless the dish is illuminated off the top or bottom. As I suggested before, it's better to shoot too high than too low.

From the first attached photo, it looks like the support arm may be angling up from the attachment point. The calculations indicate that if you extend a line perpendicular to the dish surface at the bottom of the dish, the focal point will be about 0.5" below this line.

Regardless, theory is just a starting point.

 

[Tron]

Looking great, Linuxman! That thing is beginning to look like a T-90... or rather a T-180...

With the Geosat Pro C2 C-Band LNBF group buy going on, have you considered adding C-Band to the rig as well?

EDIT: I noticed one of these Prodelin six footers atop a building today. Nothing abnormal, there are tons of them around here. But this one was pointed toward the Northwest. Perhaps I should go knock on a door

 

[linuxman]

This is getting exciting with the SL2's, I have installed two Glorystar systems using them - they work great!
Bob

Thanks Bob!!

Working great so far here too!

kudos to the mods for this project, it looks excellent!

Thanks english2fourth!

Keith Brannan wrote:

Looks very good. KUIL seems a little low, but I have seen their signal fluctuate quite a bit in the past (but then I do have it 8 degrees off-centre on a 60e dish, which would be more sensitive to minor signal fluctuations). Could be it was at a low level when you where setting it up, or it just needs a minor adjustment (after all, this was just a test day, not a "that's all there is" adjustment).

Yeah, I'm just getting started with the tuning. You guys know how long it takes me to tune a dish, so multiply that by the number of LNBF's and you know it will take a while.

Pendragon wrote:

From the first attached photo, it looks like the support arm may be angling up from the attachment point. The calculations indicate that if you extend a line perpendicular to the dish surface at the bottom of the dish, the focal point will be about 0.5" below this line.

Regardless, theory is just a starting point.

I set the support arm with my small square. I am going by Lowes today and get a bigger square just to make sure.

As you said, theory is just the starting point. The dish seems to be performing pretty well where everything is set as is, but may need improvement at the ends of the arc. We'll see.

Tron wrote:

Looking great, Linuxman! That thing is beginning to look like a T-90... or rather a T-180...

Thanks!!

With the Geosat Pro C2 C-Band LNBF group buy going on, have you considered adding C-Band to the rig as well?

I thought about that in the beginning, but decided that I have too many other C-Band dishes in service and decided that I would stick to Ku on this one.

EDIT: I noticed one of these Prodelin six footers atop a building today. Nothing abnormal, there are tons of them around here. But this one was pointed toward the Northwest. Perhaps I should go knock on a door

Start knocking. You never know what they might say.

 

[voomvoom]

Looking Good Fred..!!

 

[Mr Tony]

Very cool pics
(and I'm still envious of the flat roof)

 

[linuxman]

Very cool pics

Thanks!

I try, but sometimes my 4 year old Sony doesn't want to cooperate.

(and I'm still envious of the flat roof)

One of these days I am sure you will have a nice flat piece of land or roof with no HOA around to play on too!!

It is supposed to be very nice outside again today and I hope to get some serious tuning accomplished.

 

[linuxman]

I started shortly after 9:00 this morning. It was above 55F then, and very pleasant to be outside with the sun shining. I came in about Noon, and have been thinking things over.

So far I have it tuned and am ecstatic with 101W to 83W. KUIL on 101 is now at 40-45%, and I have the RTNs on 83W at 45%. Everything else is perfect as far as signal strength.

Finally got 79W with 11900 H at about 60% SQ, and the N transponders at about 20%. Watchable, but will go out with the first drop of rain.

I could just be happy with what I have and forget about 79W on this dish, but I think I can get it, and if I get 79W, I should be able to get 103W as well.

Both 79W and 103W are 12 degrees off-center.

I have several pictures and I want you guys who have done this before to study the angles of where the LNBFs are pointing. The closer to the ends, they all point to the high side of the dish with the exception of 79W which is extended all the way out on a 5 inch bolt and it actually is pointing nearer the center of the dish.

The problem as I see it is the black holders are in my ground clamps at an angle, so the more I extend them out, the closer the LNBF goes in towards to the dish. They work very well out to about the 3rd LNBF, but after that height is only gained by extension in. I may have to resort to a more straight up approach on the ends like a hose clamp holding the LNBF.

I also may have another solution. Pay close attention to the last picture and tell me which way to move the support platform. Up tilting the LNBFs more towards the point Pendragon plotted out in his graph, or down more towards the "center" circle of the dish. The yellow arrow points at the mark where I moved it to from it's original position the OEM installer had the support platform.

What do you think Pendragon?

If I move it more towards Pendragon's plot, the outer satellites will have more of the dish to see. I think!

I have a little more time and stamina to give to this project today, and I would like to see 79W with a little better signal.

Tell me which way to move the platform? Also tell me if you think I have it as good as I am going to get and forget about 79W and 103W.