OTHER C/Ku LNBF Ku Reception Problem Solution

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Lone Gunman

Lone Gunman

SatelliteGuys Pro
Original poster
Mar 19, 2010
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Would like a confirmation on this from “Those In The Know”.

I've got a C/Ku LNBF I'm experimenting with that has a problem of sorts receiving 103w Ku signals. I've noticed that the little antenna wires down in the Ku section don't “seem” to be 90 degrees apart like most I've looked at, so, is it OK to bend those antenna to where they are 90 degrees apart but still parallel with the Cband wires that are in front of them?

And does this have the potential to fix my Ku reception issues, ie, I'm only able to lock 2 of the 6 or so TPs that I receive with another LNBF on the same system?

Thanks,

Lone
 
If it is slightly bent it is okay to carefully bend it like it supposed to be. Can you post a pic?
 
KE4EST said:
If it is slightly bent it is okay to carefully bend it like it supposed to be. Can you post a pic?
Click to expand...

OK I was thinking that it was OK to do this but I couldn't remember where I saw that before. So when in doubt, ASK FIRST! Something I don't always do though. :oldwink

RE: Pics, hummm, not sure it will show up down in there where they are. I'll take a couple of "macro" shots and see what they look like.

EDIT: Pic attached, don't know how good you can see it though. Oh, and the Cband ones are off also.
 

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Yeah I can see it. Be careful not to strong man it and break the other side loose from the circuit board. I have straighten ones out before myself with no problem.
 
Good news, bad news. Good news, this "junk" LNBF is showing me the same Q numbers on Cband that the DMX741s was giving me.

Bad news, it won't lock ANY of the Ku NBC feeds on 103w?? :wtf2 It will lock 2 other TPs on 103w (12144 and 12180 @ 72% Q) but not 11880 or 11760 with the NBC feeds? :censored

I checked on some other sats and get the same results on the Ku stuff, ie, some will lock and some won't?

Put that old gray top DMX back on that dish and after it got warmed up, ALL the Ku NBC stuff on 103w came right back in just like before.

FYI, the Cband side of that gray top DMX741 is having cold start problems (got 2 like that). When I first start up the system it won't show me any Cband video until about 3 to 5 minutes after startup. After that, it works OK but on timed overnight recordings it will NOT lock and record the next morning unless the receiver is left on all night.

Ennywho, if I knew where this was headed a few years back, I would have ordered a CASE of those DMX741S LNBFs and Vbox 7s!! I guess hind site is always 20/20 though, isn't it!!

So I guess when I lose all the Ku capabilities on my Big Ugly Dishes, I'll have to go ahead and setup that 1m Ku dish that's been sitting here in the shop for a couple of years now. I've got everything I need for that system except the desire to put it up.

You guys are the best!! Thanks for the help! :oldwink
 
Out of curiosity are there any "hard numbers" as to the loss in KU performance with these dual C/KU Band LNBs on the smaller 4' dishes? I know it isn't "recommended" and many threads say that the KU band suffers most, but by what percentage? If you had a signal that was locked at 15db on a traditional geosat ku lnbf for example would it be a "10" on the dual c/ku band LNBs or would it be a more minimal loss (in the neighborhood of 12-13, etc)?
 
cpalmer2k said:
Out of curiosity are there any "hard numbers" as to the loss in KU performance with these dual C/KU Band LNBs on the smaller 4' dishes? I know it isn't "recommended" and many threads say that the KU band suffers most, but by what percentage? If you had a signal that was locked at 15db on a traditional geosat ku lnbf for example would it be a "10" on the dual c/ku band LNBs or would it be a more minimal loss (in the neighborhood of 12-13, etc)?
Click to expand...

I've tried it and it doesn't work at all. Not worth even attempting it.
 
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cpalmer2k said:
Out of curiosity are there any "hard numbers" as to the loss in KU performance with these dual C/KU Band LNBs on the smaller 4' dishes? I know it isn't "recommended" and many threads say that the KU band suffers most, but by what percentage? If you had a signal that was locked at 15db on a traditional geosat ku lnbf for example would it be a "10" on the dual c/ku band LNBs or would it be a more minimal loss (in the neighborhood of 12-13, etc)?
Click to expand...

Don't even bother, as they barely work all that well on even full-size 8-10ft dishes. With a 4ft dish, you need careful attention, perfect aim, a good location site, and some luck as it is to get c-band signals.

Dishes are made for what they do best. A offset ku dish does ku best with a good quality ku lnbf, and a C-band dish does C-band best with a good quality C-band lnb and feed, or lnbf.
 
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One thing you CAN do is put a Ku LNB in the dish's holder, focus it on the satellite you want, then use a C-band LNB as an offset. I've done that for 91, where 99 is the satellite the Ku band LNB is pointed at, and it works. But it takes some jerryrigging to attach the C-band LNB to the dish somehow.
 
This sounds like a challenge for me primestar31. You had mentioned that what i was able to do with dish of mine. Do they offer a dual output c ku band lnbf?
 
danristheman said:
Do they offer a dual output c ku band lnbf?
Click to expand...

No, unless you saw the end off of a dual output c-band lnbf, and mount a KU lnb there. Believe it or not, that has been done and with a Titanium lnbf. I read a post on it right here years ago, so it's here somewhere...

The hardest part would probably be matching up the little antenna probes properly inside the waveguide, so that horizontal and vertical are really what they should be when it's mounted on the dish.

Here, I found it: Hank's Titanium quad feed C/KU combo LNBF

Or this one: DMX741 C/KU LNB mod to fix drifting Ku
 
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comfortably_numb said:
One thing you CAN do is put a Ku LNB in the dish's holder, focus it on the satellite you want, then use a C-band LNB as an offset. I've done that for 91, where 99 is the satellite the Ku band LNB is pointed at, and it works. But it takes some jerryrigging to attach the C-band LNB to the dish somehow.
Click to expand...

I’m honestly surprised somebody hasn’t fashioned a plug and play bracket to accommodate both a KU and C Band LNB by now. How do you deal with the difference in degrees when it comes to motorized dishes and recording things? Could you “modify” satellites.xml somehow to correctly reflect the offset of the KU LNB if you side mounted it (or vise versus?)
 
cpalmer2k said:
I’m honestly surprised somebody hasn’t fashioned a plug and play bracket to accommodate both a KU and C Band LNB by now. How do you deal with the difference in degrees when it comes to motorized dishes and recording things? Could you “modify” satellites.xml somehow to correctly reflect the offset of the KU LNB if you side mounted it (or vise versus?)
Click to expand...

You don't need to modify that file. Simply use a different motor position number for the ku sat side, (as if it's a different sat) so it tweaks the dish over whichever way the few degrees needed.

In other words, that would make the C-band and Ku band seem like the satellites are two different sats.
 
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Once you install an offset sidecar KU feedhorn, you will quickly understand why no universal mounting solution exists. Each install is unique to the specific reflector. If I designed a bracket for my dish, it would not be optimized for yours.

Many years ago, a feedhorn / scalar (Chaparral???) was produced for adding a DSS/DBS LNB to a BUD. Performance was poor, but adequate as the mismatched DBS LNB only illuminated a portion of the reflector.
 
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Well in my case I'd like to have a larger C-BAND dish but after surveying my yard it just isn't feasible. The only Line of Sight I have for a dish is on the side of the house where the DirecTV dish is already currently. The only problem is that puts it in the side of the front yard. I've talked to the neighbors and nobody has a problem with a 4ft dish being added there, but there is no way I could get away with say an 8 or 10 footer to get everything C-BAND has to offer (we do have restrictions, but the developer never actually formed an HOA so typically when somebody wants to do something they do an informal survey of the neighborhood and if nobody objects we do whatever we wanted to do). My original plan was to put a KU dish on the side and a C-Band off near the property line or behind the house, but the line of sight there is terrible. I do want to be able to get the radio feeds on 105 from C-BAND though which many of you have demonstrated is even possible on a 90cm Dish (not ideal I know, but it seems as though it does work) so I'm trying to find the most feasible way to get the KU feeds I know I want and also the 105 C-BAND that I'd like to have with what I have to work with location wise. I'd love to have MeTV, the new Court TV and Decades, but that just isn't going to happen because of the location issues I've got.

Edit: This screenshot from Dish Pointer shows what I’m up against. This is 105W from the back corner of my house. It’s the only location I get any LOS in the back and you see how bad it is.
21e27724ce464a7a42499c857a706802.jpg
 

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