97w & 123w on Toroidal 90 dish?

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astra221

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May 31, 2005
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Hi guys,

I cant seem to find any setting for 97w and 123w to setup on my T90. I tried emailing Wavefrontier but haven't received any reply back. I have a 3 question:

1. What degree would I have to center the T90?
2. What elevation would I set the T90 for?
3. What skew would I set on the T90 for 97w and 123w to align?


Thanks in advance guys!
 
All those settings would be related to your location.
AND, there have been numerous discussions of the T-90 here on the forum in the past.
Just none that I've noticed in the last year or two.
I suspect some searching through our archives will find relevant setup-threads and details.
Our moderator, Iceberg, used to have one and has written exhaustively on them.
 
This site is truely amazing!!

:) I've been researching and stressing for the past week for hours and hours. I'm sorry you guys! Does this forum accept donations?
 
The Satlex toroid calculator gives values for the T90 that are close starting points, but the they do have errors. In particular the offsets for the LNBs tend to be on the large side. I don't recall about elevation and skew accuracies. Regardless, getting in the ballpark is still very useful as there is normally a fair amount of tweaking to do for a toroid with or without perfect numbers.
 
Im trying to combine my fta and my subscription satellites to t90. Im not allowed more than one satellite dish. Setup is: 97w/110w/119w/123w/129w

So far I only got signal quality on: (I know the difference between line quality and signal quality)
97w - 90%
110w - 91%
119w- 94%

I can't seem to get 123w or 129w.... For 123w I even used the research channel frequency 11805h to get a signal, no luck. No obstacles on the way.

I live in Dallas, Texas and setup is at the backyard which is facing directly south.
 
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I'm assuming your mounting post is perfectly plumb. If so, most likely you are having problems with skew. You didn't specify which orbital location you centered the T90 on, but there may be an easier and better way of doing this.

Because the T90 can cover about 40 degrees in orbital locations and 129W is the farthest west you can go anyway on Ku, you might consider centering on 110W. That will leave some possibilities of adding more orbital locations to the east in the future, and should make your current alignment easier. As SatLex doesn't give very accurate positions for LNBFs on the T90, I've found it's often better to simply ignore it.

If you choose to do this, put the 110W LNBF exactly centered on the T90 arm. For Dallas, your T90 elevation for 110W will be 49.3 degrees and the true azimuth is 203.4 degrees (I didn't bother looking up your magnetic declination). The T90 skew should be set to 19.5 degrees (west side of dish lower than east).

Once you have 110W peaked for maximum SQ. Put the 119W LNBF at 9-10 units on the T90 LNBF bar (east side). If your skew is set in the ballpark, you should be able to tune the LNBF holder position for maximum signal by moving it along the bar.

Now nudge the 119W LNBF mouth up and down slightly to see if the signal increases in either direction. If not your skew is decent. Otherwise you will need to crack the skew down or up on that side. It works kind of backwards as I recall - if the LNBF gets a better signal when nudged up, you'll want to rotate the skew so that LNBF goes down. Such is the fun of a dual reflector. Once you get the skew peaked on 119W, you may want to retweak its position, and in particular make sure 110W is still peaked. If not you will have to iterate, but don't change the 110W position on the LNBF bar.

After you're happy you can do the same for 123W and 129W. I would suggest putting on the 123W LNBF first, but not adjusting it because 129W has a lot more output level. Instead put the 129W LNBF somewhere around 19-21 units east of center and repeat the procedure for it that I outlined for 119W. Then do 123W. Hopefully you'll be done messing with the skew. 97W should also work pretty well.

In the end you may still need to do some tweaking overall. One other variant would be to put the 97W LNBF first on 89W or 91W after doing the 129W alignment to make sure both extremes of the T90 arc are correct. That makes adding LNBFs much easier in the future, and all but guarantees 97W and 123W can be found merely by moving the holder back and forth on the rail.

Aligning a T90 is very easy, but only when you get the hang of it.
 
I'm with you Pendragon. I have found torroids both commercial and military to be very intolerant of using data to set up and using this method alone requires more than average patience. I have set up a large number now using the spec analyser and I am always surprised by unexpected skew differentials which I put down to dish manufacturing tolerences
 
And I'm with you on the tolerance issue; skew is so critical on a toroid that it will magnify any imprecisions. There is also the problem that the Clarke belt does not appear as a circular arc to a ground observer except at the equator. The T90 design makes this simplifying assumption, guaranteeing its adjustment will always be somewhat compromised. Nevertheless I had better than expected performance on my first T90 and recently picked up a second. They're not going to replace my motorized dishes, but they will reduce the wear and tear.
 
The nearest the equator I have put up toroids is in Aden , Yemen at 12 degrees north latitude and I still had the skew imperfections. The biggest problem there I found with the toroid was I had to erect the dish then leave it for at least an hour in position in the outside temperature before final alignment.
 
what transponder should I try to get a good signal quality on, for 97w, 110w, 118/119w, 129w.

I got great signals from 91w to 129w thanks to you guys.
 
what transponder should I try to get a good signal quality on, for 97w, 110w, 118/119w, 129w.

I just look for transponders with a high SR for starters. Sometimes a weaker one is better because you can more easily measure the improvements vs. a strong transponder that is nailing a SQ of 99% no matter what you do. It's great to hear that everything is lining up!
 
according to lyngsat the polarity on TP1 for 129w should be vertical which I dont get a SQ for, but I do get a SQ if I change it to horizontal. There are a few TPs on 129w with this issue. Should I leave them be or should I change them?

is 119w apart of 118w? are they seen individually? I shouldnt worry about 119w

I get a great quality throughout the 4 satellites. Thanks you guys!!
 
according to lyngsat the polarity on TP1 for 129w should be vertical which I dont get a SQ for, but I do get a SQ if I change it to horizontal. There are a few TPs on 129w with this issue. Should I leave them be or should I change them?

Are you on G-27 or Ciel 2? Are you using a reversed polarity LNBF if on Ciel 2?

is 119w apart of 118w? are they seen individually? I shouldnt worry about 119w

118.7 (Anik F3) is a different bird from 119 (EchoStar 7). They are so close together that a single LNBF could pick them if it could cover the full frequency range. DN makes a unit that does this for their dishes. Nothing that I know of in the FTA market can do this, however. You only need 118.7 if you subscribe to international channels on DN.

If you are a DN subscriber AND want the international channels AND you have to do this on a toroid, you will probably have to convert a Dish 118.7/119 LNBF to perform reverse circular reception. If that's the case, let me know. I'm pretty sure it can be done as I've converted other Dish LNBs to be toroid-compatible.

I get a great quality throughout the 4 satellites. Thanks you guys!!

The accolades are for you because you made it work. Not everyone is willing or able to put up with the learning curve of a toroid and figure out how to make it fly. Congrats!
 
Are you on G-27 or Ciel 2? Are you using a reversed polarity LNBF if on Ciel 2?

Im on Ciel 2 and yes I do have a reversed polarity LNBF, a M20R. I do need international thats why im on dishnet.... anyways I searched around for hours and found no answer. I get great SQ on almost all TP and like I said some TPs like tp 1, tp 3 I have to change polarization to horizontal to get a SQ and tp 4 i have to change to vertical to get SQ, even though lyngsat has it the other way around.
Anyways I'll try to figure it out and keep you guys posted.
 
Im on Ciel 2 and yes I do have a reversed polarity LNBF, a M20R.

If you're subscribed to DN why not connect your Dish receiver to the 129 LNBF and do a check switch? Last time I looked, the low TPs on 129 were spotbeams and you may or may not be able to receive any given one in your area.

I do need international thats why im on dishnet.

Let's resolve the 129 issues first. Receiving 118.7 can't be done with M20R, but there are other options.
 
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