https://aerial.obchodmrp.sk/lnb-uni-gi-209-flange-platinium-golden-i.-1213 one link from najnakup. Najnakup itself is web page where all offers from many web stores are put together.
Prime-focus dish - LNB recommendation
- Thread starter Espinosa
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I would recommend to start from Single LNB, get reception results and only then think about many-output LNB.
Espinosa
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Sure, I will definitely order that one you recommended. But what after that? If it performs better than IBU which I expect, what would be the next step? For my needs only 4 or more outputs would be fine.I would recommend to start from Single LNB, get reception results and only then think about many-output LNB.
When you have played enough with Single, go for Quad LNB https://adishnetservices.com/product/stargold-sg-940-ku-band-lnb/
Motogato
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Good idea for my new 3.4m dishHi guys, thanks for the good words. I think you are thinking too good about my abilities. Anyway, for PFA, even I do not like multifeeds (on not multifocus antennas, and especially PFAs), I would prefer multifeed solution C+Ku instead of combo LNB. Once I had combo LNB but did not like as it performed. One of the best Ku-band LNBs for PFA IMHO is GI-209P. It is very cheap but works just great.
There are couple of pictures of what I mean.
Espinosa
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Hmm, how is playing with Single correlated with buying Quad?
Also, may I know do you recommend this Quad LNB because it has an integrated feedhorn or perhaps you have tested it?
Very simple correlation.... Quad will cost you at least 5x more than the cheapo Single. And also, when you have tested different options, you can compare performance results to understand what is good and what is not.
I can not recommend this Quad for you, as I did not have it and just googled it for you. Try to google a little bit more to find users' reviews.
From the pictures and shop's description, I see it as good quality, factory made product with integrated feedhorn and ready to be used straight out of the box.
Another option for you to visit satellitesuperstore and ask them whether they can provide you Quad flange LNB and also the feedhorn for PFA. As far as I know they can find you any kind of satellite equipment, for your money of course.
Thanks, @Barney, but I don't know if the only solution for poor signal reception is the scaling rings I use. Probably, there are others, but for me, it is the only viable and safe solution for a better reception with a 1.50m antenna.
I posted my results with Ku-band scaling rings somewhere on the forum, but I can't find that post.
Therefore, because I don't have time to write that article again, I'll be forgiven for giving a link where I talked extensively about these scalar rings. If this is not allowed, you can delete it.
I have tried other scalar rings, but the best result is in the Ku band I got with these rings. Unfortunately, these scalar rings are no longer available at Aliexpress.
I posted my results with Ku-band scaling rings somewhere on the forum, but I can't find that post.
Therefore, because I don't have time to write that article again, I'll be forgiven for giving a link where I talked extensively about these scalar rings. If this is not allowed, you can delete it.
I have tried other scalar rings, but the best result is in the Ku band I got with these rings. Unfortunately, these scalar rings are no longer available at Aliexpress.
Espinosa
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'ere, buy wan of these, it is an Invacom ADF adjustable scalar feed/waveguide for a C120 LNB.
.
Espinosa
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I need Quad LNB, Inverto and Invacom C120 Quad LNBs are not available. I don't know what other options are. Satellitesuperstore offers a Primesat Quad LNB, but I don't know how it performs. And it's quite expensive.
You got 4 options:
1. Buy the quad C120 from Satellite Superstore.
2. Get someone to convert you a quad 40mm collar LNBF such as an IBU or similar LNBF to a C120 flange fitting. Or do it yourself.
3. Check online marketplaces such as eBay or Facebook for a used/new model.
4. Go without.
Up to you now.
Hi There,
I think this is the right thread for this question.
Is the adjustment to a standard LNB for KU band by adding scalar rings, very likely to provide an increase in signal performance?
Thanks.
Espinosa
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Hehe, I already listed in my mind all possible options and perhaps I'm biassed but I like second option the most. For now I think I will buy Invacom feedhorn and probably Inverto Twin C120 to see how it works. Also, would like to compare performance with GI-209P. After that I will probably try to convert IBU LNBF to fit Invacom feedhorn. I hope @RimaNTSS is willing to give some hints how to approach that task.
A 40mm collar LNBF for an offset focus dish already has scalar rings as part of its build. Take the plastic end cap off and have a look.
Some people have used a C120 LNB on an offset focus dish by bolting it on to a Channel Master or Gibertini feed horn. Both these feehorns are built with scalar rings.
For a Prime Focus dish it depends if the manufacturers original feed is being used.
In the case of Precision Antennas, their original feed already has inbuilt scalars on the machined block that attaches to the feed support arms.
In this scenario there is no added value in trying to use aftermarket scalar rings.
For a Prime focus dish where the manufacturers original feed is not available then the Invacom ADF feed with adjustable scalar ring will add SNR dB.
The simple test is to remove the threaded scalar from the end of the feed and watch the SNR dB reduce.
The other point to consider with adjustable scalars is they they have an optimum position.
Too far back and they let through ground noise. Too far forward and they impinge on the feed illumination of the dish.
The Invacom ADF threaded scalar is useful because of the thread which allows fine tuning of its position to maximise SNR dB.
There you have it, you decide...
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Thank you @moonbase. I did exactly what you advised and had a look.
I can see the rings clearly, the structure and how they are attached. It's far more simple than I thought.
All these years I thought there was a very complex arrangement behind the plastic cover.
If I were to make any adjustments or fiddle with this, the key issue would be making the
LNB watertight again after my modifications.
You are in the building trade, water proofing should be second nature.
Rubber self amalgamating tape or outdoor rated sealant come to mind as possible options.
Some people have been known to use gasket sealant on LNB's
I dont really see why you would want to modify a 40mm collar LNBF if it is to be used on an offset focus dish?
It has the scalars and is waterproof. The only reason I can think of would be to convert it to a C120 flange LNB to be used with something like an Invacom ADF feed with adjustable scalar?
If you wanted to do this conversion there is a quick cheat.
Buy an Invacom C120 single output LNB and remove the C120 flange end fitting from it, it pulls off or can be gently tapped off, it is not bonded or machined in place.
Get an Inverto Black Ultra LNBF or something similar, cut off the scalar head and shove the remaining waveguide neck into the C120 flange fitting with something like JB Weld putty in it.
The JB Weld forms a strong seal and job done !
I can claim no credit for the above quick cheat, it is all documented elsewhere by DX Men who really do know their stuff.
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It was more of a statement, than a question. I was just showing my enthusiasm and appreciation for your help and advice,
as I am learning a lot and truly enjoy this hobby.
I already have some ideas and my thoughts tell me that the quality of the material used for the scalar rings can also
affect the relative signal change.
@moonbase I like to test things and try out options if I have the time, that's the reason why I might do a bit of DIY and make some
adjustments to see if I can increase the signal.
I am compelled to reply. There seems to be a bit of fuzziness on the scalar subject. And please accept my personal experience from quite a few "bringing back to life" of old prime focus dishes.
You should shy away from lnbf and flange combinations if the feed throat depth cannot be adjusted separate from the scalar position.
You would think that every dish will be a perfect parabaloid. Unfortunately it is not so.
In a ideal world a 4 meter dish would set perfectly inside of a 5 meter dish, a 3 meter inside of that. And so on. But it may not be so unless you have dishes by the same manufacturer or those who manufacture to strict design specs. Andrews, Prodelin, milspec., etc. They do.
There are calculations where stretching strings across a dish face and measuring the diameter and center depth. And determining the f and f/D.
Then you know where a scalar should be positioned and where the feedhorn throat should be set in relation to the dish center.
Again. Only for a perfect parabolic shape.
Try to think of an artificial solar or lunar eclipse. You hold a disc in front of your eye and move it out or in until you see only the very edge of the moon or sun.
The perfect position for a scalar is where you're not "blinding" a portion of the diameter and not exposing more than the diameter. Get it?
Then. Moving the lnbf throat in or out for signal peak. While retaining proper skew angle. And assuring the throat points at the exact dish center.
So as you should see. A fixed lnb/flange may not let you experience the best performance you could.
In my image. At the initial setup of a c band scalar and lnbf for c band.
The f & f/D calculations were performed. Everything was bolted in place per the results. The lnbf was peaked for signal.
Although the calculations and lnbf spec sheet said to set the f/D to, let's say, 30. Actual signal peak was when the throat was a bit closer to the dish face.
The photo is from setting up an adjustable scalar depth method by the way of long bolts and lock nuts.
When finished, everything that looks off-kilter was perfectly aligned ans well as could be.
The Geosat Pro ku banf lnbf "sidecar" setup is there and looks offset. I have a buttonhook feed with the extension arm bolted to an aluminum casting at the dish face.
Aiming the ku lnbf at the center of the dish killed a portion of the signal. So an offset of ~5 degrees East was found the be a good placement.
And even though the ku lnbf is on a 12' dish. It only sees a little over 1m of it.
That is where a proper lnbf/scalar would be much better. There are tricks where people are removing the weather shield from the front and cutting off a portion of the built in scalar.
As the lnbf is for an offset feed dish, its appearance is indeed a cone. As opposed to a flat face scalar of the c band one.
There is mention of waterproofing. Not a bad thing. But I believe a little breathing necessary too. There are feed boots out there. For my amateur radio coax connections I use clear Flex Seal. Over 6 years on a few connections in the tower and still working great. Nothing fancy, no Coax-seal self amalgamating tape. Perhaps mask off a flange and give it a few coats and call it a day. And save the rest of the can to make a screen door boat.
Not looking for negative replies on this one guys. I've done it quite well so far. And it took a few tries to get there. Now its repeatable and works perfect.
Feed
You should shy away from lnbf and flange combinations if the feed throat depth cannot be adjusted separate from the scalar position.
You would think that every dish will be a perfect parabaloid. Unfortunately it is not so.
In a ideal world a 4 meter dish would set perfectly inside of a 5 meter dish, a 3 meter inside of that. And so on. But it may not be so unless you have dishes by the same manufacturer or those who manufacture to strict design specs. Andrews, Prodelin, milspec., etc. They do.
There are calculations where stretching strings across a dish face and measuring the diameter and center depth. And determining the f and f/D.
Then you know where a scalar should be positioned and where the feedhorn throat should be set in relation to the dish center.
Again. Only for a perfect parabolic shape.
Try to think of an artificial solar or lunar eclipse. You hold a disc in front of your eye and move it out or in until you see only the very edge of the moon or sun.
The perfect position for a scalar is where you're not "blinding" a portion of the diameter and not exposing more than the diameter. Get it?
Then. Moving the lnbf throat in or out for signal peak. While retaining proper skew angle. And assuring the throat points at the exact dish center.
So as you should see. A fixed lnb/flange may not let you experience the best performance you could.
In my image. At the initial setup of a c band scalar and lnbf for c band.
The f & f/D calculations were performed. Everything was bolted in place per the results. The lnbf was peaked for signal.
Although the calculations and lnbf spec sheet said to set the f/D to, let's say, 30. Actual signal peak was when the throat was a bit closer to the dish face.
The photo is from setting up an adjustable scalar depth method by the way of long bolts and lock nuts.
When finished, everything that looks off-kilter was perfectly aligned ans well as could be.
The Geosat Pro ku banf lnbf "sidecar" setup is there and looks offset. I have a buttonhook feed with the extension arm bolted to an aluminum casting at the dish face.
Aiming the ku lnbf at the center of the dish killed a portion of the signal. So an offset of ~5 degrees East was found the be a good placement.
And even though the ku lnbf is on a 12' dish. It only sees a little over 1m of it.
That is where a proper lnbf/scalar would be much better. There are tricks where people are removing the weather shield from the front and cutting off a portion of the built in scalar.
As the lnbf is for an offset feed dish, its appearance is indeed a cone. As opposed to a flat face scalar of the c band one.
There is mention of waterproofing. Not a bad thing. But I believe a little breathing necessary too. There are feed boots out there. For my amateur radio coax connections I use clear Flex Seal. Over 6 years on a few connections in the tower and still working great. Nothing fancy, no Coax-seal self amalgamating tape. Perhaps mask off a flange and give it a few coats and call it a day. And save the rest of the can to make a screen door boat.
Not looking for negative replies on this one guys. I've done it quite well so far. And it took a few tries to get there. Now its repeatable and works perfect.
Feed