120cm dish with C-Band performance - Now with HD!
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Alec said:
Wow, this is exactly what we've been talking about.
Do they give any results on how well this setup performs?
Will anyone try this now that it's been shown it works?
I just can't see how this would not degrade Ku signal significantly?! Wouldn't alot of signal be blocked by the tube of the c-band lnbf ? Plus Ku Lnbf would not realy be at the focal point. Hopefully I am wrong This would be the best possible solution if possible.
This would be the best possible solution if possible.
I would imagine (not being a rocket scientist like Alec, etc ) that the "focal point" is extended by the C-band tube. The waves bounce along the inside to reach the C-band V/H elements, but instead of hitting the end and going back, it is just extended into the Ku LNB's feedhorn. There it can hit THAT lnb's H/V elements, THEN bounce back.
Of course, the biggest question (I think) is how badly all this bouncing screws up the waveforms, and how much it reduces the performance. I'd hazard a guess that the above-pictured C/Ku combo DOES work, the million dollar question is, how well? Until we make one (or fully translate the forum it was pulled from ) we won't know.
) that the "focal point" is extended by the C-band tube. The waves bounce along the inside to reach the C-band V/H elements, but instead of hitting the end and going back, it is just extended into the Ku LNB's feedhorn. There it can hit THAT lnb's H/V elements, THEN bounce back.Of course, the biggest question (I think) is how badly all this bouncing screws up the waveforms, and how much it reduces the performance. I'd hazard a guess that the above-pictured C/Ku combo DOES work, the million dollar question is, how well? Until we make one (or fully translate the forum it was pulled from
) we won't know.I have to give credit to spindoctor for sending me these links, hes stated that its ok by him to pass them on. The first link is of a Russian web site much like this one, the 2nd link is needed to translate the Russian language. Its a little tough understanding what they are saying, but you'll get the idea. There are some great photos of thier experiments ! (1) http://www.forum.alyno.ru/phpBB2/viewtopic.php?t=172
(2) http://babelfish.altavista.com/tr
(2) http://babelfish.altavista.com/tr
take a look the feeds on the same forum
oh and you got to see the magic plate
reducing your dish from 1.2m to 90cm
and other interesting stuff
oh and you got to see the magic plate
reducing your dish from 1.2m to 90cm
and other interesting stuff
no need for thanks
and they are doing all this when is 50 below zero
i bet some vodka helps
and the last picture on page 4 should take the emmy
2 lnbf next to one another and KU on the back.
and they are doing all this when is 50 below zero
i bet some vodka helps
and the last picture on page 4 should take the emmy
2 lnbf next to one another and KU on the back.
Alec said:
You mean this post.
http://www.satelliteguys.us/showpost.php?p=546214&postcount=251
If so this is a dual polarity feed. On a feedhorn like this each LNB recieves a different polarity (one horizontal and one vertical). The purpose of feeds such as that are to allow reception of both polarities at the same time. This is useful if you have multiple recievers and you want to watch channels that are on different polarities on some of those recievers. They can also be used along with a 13/18v switch to get 13/18v polarity switching by connecting the 18v input to the horizontal LNB and the 13v input to the vertical LNB. Anyway, if you design your feed like that you'll only get one polarity on your Ku LNB. If youguys want both C and Ku band and both polarities there are a couple of solutions. The first is to use the traditional Corotor design, but if you dislike that approach because it uses a polar server and needs a reciever capable of controlling it then there's another solution. This other solution is a Bullseye type feedhorn or dual C dual Ku feedhorn. This is what I use on my 8.5' birdview. This is a more expensive solution as the bullseye feedhorn itself is more espensive and you have to buy 4 LNBs (2 C and 2Ku) and a switch to connect them all together and allow you to switch between the LNBs. So as you can see it gets expensive really quick but it's the only combination that'll do all you want without using a polar servo. Here's the feedhorn I use.
http://www.daveswebshop.com/pmcku.shtml
I then use a switch like this one (I got mine alot cheaper on ebay).
http://www.sadoun.com/Sat/Products/Channel-Master/6904IFD-Multi-Switch.htm
This provides 22Khz switching between C and Ku and 13/18v polarity switching.
Stefan, thanks. I think whats developing is that some of us now have both a ASC421 and a Invacom .03 and are looking for a way to combine both into a single feed rather than spend any more money on lnb's and feed horns. The Russians seem to have been studying this issue for some time now.
now if we can incoporate this little chip http://www.st.com/stonline/books/pdf/docs/10465.pdf with the lnb will be in heaven
Great pics Stefan. I maybe could have found some results with turning the adapter I had built, but seems adapter would have been very limited at best. I am, at present, waiting for "JB Weld" to set on my "Russkie" motivated C/Ku adapter. Results, hopefuly tomorrow.........One thing I would like to comment on, is the great support of people here, no flamming, etc. Ive been reluctent to post experiment failers, but deam it nessessary to help the learning prosess. My greatest thanks to everyone ! Alec
Alec said:
You're a true pioneer, Alec, and a great help to us wether reporting on non-working attempts or great successes. I and many others are watching this thread with great interest now that so many people are going MicroBUD and really need some sort of dual C/Ku assembly. I can't wait to hear even just IF the dual setup you made works, let alone how well
Keep up the great work!
C Ku combo
Tried this out today. Ku wave guide made from 3/4" copper fittings, 4 degree tapper on end for Invacom. Ku opening set back 1.5" from front of C wave guide entrance. On G10/ku 12114 V 4.444 usualy has 99% quality for me, with this adapter, was at 30%. On G10/C on TP 16 10-15% at best. Ku wave guide seems to blocking C band signal. I may tried placing the Ku entrance more out in front like the Russian unit in photo in above post.
Tried this out today. Ku wave guide made from 3/4" copper fittings, 4 degree tapper on end for Invacom. Ku opening set back 1.5" from front of C wave guide entrance. On G10/ku 12114 V 4.444 usualy has 99% quality for me, with this adapter, was at 30%. On G10/C on TP 16 10-15% at best. Ku wave guide seems to blocking C band signal. I may tried placing the Ku entrance more out in front like the Russian unit in photo in above post.
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Alec, try a square tube waveguide with a right-angle instead of the bend, it'll probably work a lot better.
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