Lbn throat sizes question

[cruzin]

Are there any smaller throat standard lnbs on the market. I have dishes that use the smaller throat lnb feedhorns (1.093 = 27.76mm) My lnb brackets fit the smaller ones. I ground out a larger area for the 40mm throat lnbs and had no luck with them on sat 83 for RTN. I figure becasue the 40mm center height is just slightly higher than the 27mm sits down in it. I put the smaller original feedhorn with lnb attached on back on and it tuned right in. The lnb on there now attached to feedhorn is a 1.6 noise ratio and do not know the gain. I can get a norsat to bolt on my feedhorn but they are pricy. I have looked for smaller throat standards but not finding any. Would like to get that noise number down.
And a question about the noise ratio of the commercial lnb such as Norsat.
their affordable one (50.00) is a 0.6 noise and the ones I have read reviews about here on the forum such as TechSat tracker II gets down to 0.2.
Are these ratios that accurate? Can one compare a commercial to aftermarket China made lnb? Right now with the original 1.6 noise lnb with unknown manufacture I get a 69-87 signal quality jumps back and forth with a cs5000 with a 1.2m dish. Can someone suggest a improvement with a low noise with a smaller neck to fit my holder or a norsat with lower noise?
Getting 69-87 Q looks fine on tv, would the cost of norsat be worth the investment?

And a cover for my feedhorn opening. Where can they be bought or can someone suggest what to use to construct one as hornet season is coming.
thanks for any suggestions and information on obtaining a lnb with the 27mm neck.

 

[turbosat]

cruzin you prob have to fashion a cover out of a plastic jug or something, or just cut up a thick garbage bag like I do, lol. They last a couple of months in the sun (you could double-bag it I guess). IF you don't care what it looks like, that is. One reason I like the old primestar lnbs is because of that weather-cover, does the job nicely.
Now, hornets you shouldn't have to worry about, they build a paper nest that gets a big as a basketball sometimes, never saw one start a nest in a dish. Red wasps is the thing to watch out for. Painful, but no comparison to hornet sting.

 

[cruzin]

thanks for the cover tip turosat.

cruzin you prob have to fashion a cover out of a plastic jug or something, or just cut up a thick garbage bag like I do, lol. They last a couple of months in the sun (you could double-bag it I guess). IF you don't care what it looks like, that is. One reason I like the old primestar lnbs is because of that weather-cover, does the job nicely.
Now, hornets you shouldn't have to worry about, they build a paper nest that gets a big as a basketball sometimes, never saw one start a nest in a dish. Red wasps is the thing to watch out for. Painful, but no comparison to hornet sting.

 

[cruzin]

When all else fails me, I look in the frig! found that the cover of a frozen juice container fit the second ring on the feedhorn and a very snug fit, I cut a small notch in the bottom for water to exit. It seems I lost some q on the signal although it may be I moved it a bit. But it looks good.
Also painted my twins the other day.

confirmed loss of Q is due to cover, I went out removed the cover and q went back to 87, put it back on again went to 70.

 

[B.J.]

When all else fails me, I look in the frig! found that the cover of a frozen juice container fit the second ring on the feedhorn and a very snug fit, I cut a small notch in the bottom for water to exit. It seems I lost some q on the signal although it may be I moved it a bit. But it looks good.
Also painted my twins the other day.

confirmed loss of Q is due to cover, I went out removed the cover and q went back to 87, put it back on again went to 70.

I'm curious relative to what brand, and where you get that feedhorn? I assume from what you say that you can connect any standard Ku LNB to it? I've seen Invacom feedhorns, but I don't think it takes standard LNBs, just an Invacom LNB, but I may be wrong.

Can I assume that this setup will not have switchable polarity?

 

[cruzin]

Hi, the lnbs came on the dishes. I pulled them off buildings we bought the equipment from. The buildings were going to be demoed. From what I gather you can buy any of those commercial lnbs and bolt them to the feedhorn as long as the bolt holes line up. But I believe it may be limited to ku and the band it is made for.
I think I am getting both h & z as I get both of the RTN feeds east and west. I think one is H and one is Z. But I may be wrong and just not knowing. Someone correct me if I am wrong. I do not know if the stations can have a h or z or is the transponders h or z?
I had 3 of them and they all worked, on one of them it had chapparel stamped on it. The other 2 feedhorns do not have any markings. Only one of the lnbs have a name (Echostar)
Hope this clears up the question.

 

[turbosat]

That lnb-cover looked made to order, but if it cuts your signal that much, gotta toss it and keep looking! Musta made that plastic with lead in it lol. Nice painting, not nearly so outlandish as my purple people eater primestar. It's all for fun though.

 

[B.J.]

Hi, the lnbs came on the dishes. I pulled them off buildings we bought the equipment from. The buildings were going to be demoed. From what I gather you can buy any of those commercial lnbs and bolt them to the feedhorn as long as the bolt holes line up. But I believe it may be limited to ku and the band it is made for.
I think I am getting both h & z as I get both of the RTN feeds east and west. I think one is H and one is Z. But I may be wrong and just not knowing. Someone correct me if I am wrong. I do not know if the stations can have a h or z or is the transponders h or z?
I had 3 of them and they all worked, on one of them it had chapparel stamped on it. The other 2 feedhorns do not have any markings. Only one of the lnbs have a name (Echostar)
Hope this clears up the question.

THanks. Neat.

Re polarity, if you're talking RTN on ACM9, both east and west are on the same horizontal transponder, so getting those two doesn't mean you're getting both polarities. I can't imagine any way that you could get both polarities with a replacement LNB like a Norsat.
I'm curious whether you've had the lnbs off those things? If so, is the part you call the feedhorn open all the way to the LNB, or is it closed off with probes on both sides of where it's closed off (confusing wording)? Also, is the wave-guide where it connects to the LNB cylindrical or rectangular??
The reason I ask, is that replacement LNBs like a Norsat or Cal-Amp have rectangular wave guides, whereas with that narrow cylindrical throat almost certainly have a circular waveguide at the throat area, but perhaps it's closed off where it connects to the LNB, and converts to a rectangular waveguide, but that doesn't seem likely.
I have an *OLD* {1980s era} General Instruments LNBF that has a front section that looks similar to your feed, ie a broad scalar ring (mine's more conical), and a very small cylindrical throat, connecting to what seems to be an LNB via a round flange with numerous screw holes similar to yours. However on mine, it is a round waveguide on both sides of the flange. Ie I couldn't connect a replacement LNB because that would have a rectangular waveguide.
Anyway, I've never run into a small feedhorn like yours that would accept replacement LNBs. If it does, then that's interesting, but I really don't think it would do polarity switching.

Re the "hornets", there are many different kinds of hornets. The type mentioned above that make the HUGE nests would never build in a feedhorn. Also as mentioned above, usually it's wasps that build in feedhorns, and while they will sting, usually if you get a couple feet away from their nest, they will leave you alone, compared to a hornet, that will follow you across a yard into the house and out the door to the other side of the house. Hornets are really agressive. But the reason I'm commenting on the hornets, is that in addition to the big nest hornets, and yellow-jacket ground type hornets, the past several years, we've had a wierd type of hornet nest on our house/garage. I think I looked it up, and it was something like a white faced hornet. But their nests start out as the strangest looking things I've ever seen. Sort of a golf ball sized core where it connects to the building, and below that a long tube, about 1/2" diameter. Really wierd looking. It stays this way for quite a while, but eventually the hornet builds the paper covering around the long tube, but it never gets big, like those monster things. I've also seen another type of hornet that seems to build nests in enclosed spaces in decks and stuff, but I don't know what kind of hornet those are. Perhaps they would build in a feedhorn, I don't know. But back to the wasps, I generally take the feedhorn cover off my BUD in the summer, because I almost killed myself once when I went up on the top step of a ladder once to work on the feed, took it off to find a big wasp nest inside. Scared me enough that I tried to run, while still on top of the ladder. My feet, and the top of the ladder went one way, the rest of me went the other way, and I fell horizontally 6', hitting a big 4' rock that was next to my ladder. I could hardly walk for weeks after that. After that, I decided to take the cover off, so they won't build in there.

 

[cruzin]

Hi, ya I had questioned if it got both h and z. I do not think it does. Not alot of good unless you find something like rtn to use it on. I wonder if you could turn it 90 deg and get vertical? Yes they have a rectangular area down there. I have 2 types one must have a o-ring because you can see down in the lnb and I see a small pin down there and the one I have here in my hand is blocked off with what looks like white plastic (gasket). I suppose that dish I have that lnb on is only good for what I am doing with it. Although I have the one to the left of it and I have the more common 40mm throat lnbs on it. Could motorize one someday.but there are rather inexpencieve 1.2 dishes for motorizing out there.
Maybe those hornets with the white face are "ballface hornets" if so they are mean. They build in trees or on buildings. Make a horn type looking nest. Very mean, larger type. I got stung by one years back in the chest and within a couple hours I had blotches all over my body.

THanks. Neat.

Re polarity, if you're talking RTN on ACM9, both east and west are on the same horizontal transponder, so getting those two doesn't mean you're getting both polarities. I can't imagine any way that you could get both polarities with a replacement LNB like a Norsat.
I'm curious whether you've had the lnbs off those things? If so, is the part you call the feedhorn open all the way to the LNB, or is it closed off with probes on both sides of where it's closed off (confusing wording)? Also, is the wave-guide where it connects to the LNB cylindrical or rectangular??
The reason I ask, is that replacement LNBs like a Norsat or Cal-Amp have rectangular wave guides, whereas with that narrow cylindrical throat almost certainly have a circular waveguide at the throat area, but perhaps it's closed off where it connects to the LNB, and converts to a rectangular waveguide, but that doesn't seem likely.
I have an *OLD* {1980s era} General Instruments LNBF that has a front section that looks similar to your feed, ie a broad scalar ring (mine's more conical), and a very small cylindrical throat, connecting to what seems to be an LNB via a round flange with numerous screw holes similar to yours. However on mine, it is a round waveguide on both sides of the flange. Ie I couldn't connect a replacement LNB because that would have a rectangular waveguide.
Anyway, I've never run into a small feedhorn like yours that would accept replacement LNBs. If it does, then that's interesting, but I really don't think it would do polarity switching.

Re the "hornets", there are many different kinds of hornets. The type mentioned above that make the HUGE nests would never build in a feedhorn. Also as mentioned above, usually it's wasps that build in feedhorns, and while they will sting, usually if you get a couple feet away from their nest, they will leave you alone, compared to a hornet, that will follow you across a yard into the house and out the door to the other side of the house. Hornets are really agressive. But the reason I'm commenting on the hornets, is that in addition to the big nest hornets, and yellow-jacket ground type hornets, the past several years, we've had a wierd type of hornet nest on our house/garage. I think I looked it up, and it was something like a white faced hornet. But their nests start out as the strangest looking things I've ever seen. Sort of a golf ball sized core where it connects to the building, and below that a long tube, about 1/2" diameter. Really wierd looking. It stays this way for quite a while, but eventually the hornet builds the paper covering around the long tube, but it never gets big, like those monster things. I've also seen another type of hornet that seems to build nests in enclosed spaces in decks and stuff, but I don't know what kind of hornet those are. Perhaps they would build in a feedhorn, I don't know. But back to the wasps, I generally take the feedhorn cover off my BUD in the summer, because I almost killed myself once when I went up on the top step of a ladder once to work on the feed, took it off to find a big wasp nest inside. Scared me enough that I tried to run, while still on top of the ladder. My feet, and the top of the ladder went one way, the rest of me went the other way, and I fell horizontally 6', hitting a big 4' rock that was next to my ladder. I could hardly walk for weeks after that. After that, I decided to take the cover off, so they won't build in there.

 

[Tron]

Cruzin, it looks like a C-120 flange, but I could be wrong. There are feedhorns out there with flanges that closely resemble C-120, but the bolt holes are off ever so slightly. That was the case on a dish I helped a friend remove from an ex-post office.

The Norsat LNBs are single polarity, meaning they will only receive H or V, depending on their orientation. While the noise figures sound incredibly high for these LNBs, the L.O. stability is usually excellent compared with consumer LNBs. I have a Norsat .9 NF LNB that performs about the same as my Invacom .3

 

[B.J.]

.....
Maybe those hornets with the white face are "ballface hornets" if so they are mean. They build in trees or on buildings. Make a horn type looking nest. Very mean, larger type. .....

Yeah, the hornet was a "bald face" hornet, not a white face.
Nest is very weird looking. See picture below of one attached to bottom of 4x4 deck rail.