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11-16-2004 06:06 PM #1
Adjust scalar ring (large dish) to improve quality!
I've been having problems getting in some of the weaker satellites, such as AMC-7. Just out of sheer frustration I tried playing with the scalar ring adjustment and picked up another 15-20 points in quality just by moving it in and out until I got the best reading! Normally they tell you to use a mathematical formula and set it to a certain position, well I have to tell you that at least on mine, the place where the formula told me to put it was not the place where I got optimum reception. In my case I had to slide it slightly closer to the end of the feedhorn (or to put it another way, closer to the dish itself).
With some types of mounts you may have to pull the feedhorn in or out of the ring after loosening the setscrew; if you do, remember you are changing the distance of feedhorn to dish so you may have to re-optimize that as well (in fact the two adjustments probably interact, so if you put a little time in tweaking both you may be able to do even better than I did). I was surprised that the formula didn't produce the best "real world" results but hey, I'll take any improvement I can get, especially when it makes the difference between a signal breaking up frequently and getting a good, clear, steady signal!
So if you've played with azimuth and elevation adjustments and still can't get the quality you are looking for, it just may be that a little movement on the scalar ring could make a big difference! Note that this applies to large dish (C-band, or C/Ku combination) feedhorns only - generally the small dish feedhorns don't have scalar rings.
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11-20-2004 11:14 AM #2Supporting Founder
Be carefull, as I remember from the Golden Age of Satellite, 1980s, we would max out the signal and then move the feed in approximately 1/4 to 3/8th of an inch. When you max the signal you are probably picking up a bit of ground noise which on the old analog receivers would give you a trashy picture.
11-21-2004 10:25 PM #3
This is what work for me too on amc-7 but when i got the best quality on amc-7 I lost that fox station ( KUIL ) on amc-4. so i change it back to get the best quality on amc-4 first and now amc-7 is okay .
now i`m work on trying to get cbs on Gr-10Ku
11-23-2004 09:11 PM #4
I recommend you to call in a dealer or friend who has a spectrum analyzer and have the reflector peaked to its optimal performance. I get mine done pro every 2-3 years and would like to get a spectrum analyzer my self but they are pricey. What size dish do you have is also a big part in receiving C-band but Ku is ok for a smaller sized reflectors mesh holes must be tight (ku) solid is best. Due to 2 degree spacing one must have a minimum of an 8.5’ dish. I never let anyone play with my dish without a spectrum analyzer.4DTV DSR922 HDD 200 VC 2+ GI2500R VC 2 Pansat 2500a c/ku/dbs feed Norsat 5215 C-band Norsat 6606a Ku-band Lnbs 10.6ft Clearview mesh AMC-8 to AMC-12 24" Venture arm.
11-24-2004 04:20 AM #5
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Must be nice....Originally Posted by tdti1
Now, I grant that this system was about as far from state of the art as you can get - think old LNA system that you pretty much had to position by eyeballing the dish to get close and then peaking it manually, because the numeric position display was broken. But nevertheless, I wasn't satisfied so I got a book from the library on satellite TV (the book was old, which made it a perfect fit with the system!) that was to this day the only place I've ever seen it clearly explained how to track the arc with a big satellite dish.
The key for me was when I figured out that you ONLY adjusted the elevation while pointed at the southernmost bird you can see, and then you went to the westernmost bird (I'm in the east) and loosened the dish on the pole and then tried going a little east or a little west (repeaking the receiver after each small move) until you got the best picture on the westernmost bird. Then back to the southernmost satellite to peak up the elevation (if necessary), then bach to the westernmost bird and re-peak that, and so forth until any further adjustments resulted in no significant improvement. As long as the pole was straight this would track the arc. Well guess what, I finally got brave enough to try it with mine (my fear was that it really was as good as you could get and I would just mess it up) and lo and behold, I got significant improvement.
Of course things got a whole lot better when I switched to a more modern feedhorn (with C and Ku LNBs) and a much newer C-band receiver, both acquired used but in good shape. Of course I had to get a new positioner arm too, and making that work with that old dish took some creativity too.
Anyway, it's a ten foot dish (black mesh with small holes, about the only part of the system that was and still is in good shape) so with new LNB it made a massive improvement. But Ku never came in all that great until I finally started doing some tweaking for that.
There is only one realy problem with this dish - whoever was the genius that designed the thing, they did not leave any way to adjust the distance from the end of the feedhord to the dish - AND THEY GOT THE LENGTH WRONG!!! It's hard to explain how they managed this but basically they arm ("buttonhook" style) is welded to a flat plate, and the feedhorn clamps to the end with a U-bolt. There is a little play (maybe an inch or so tops) but at the furthest out you can go with the feedhorn, it's still maybe an inch or so too close to the dish.
So what I think is that maybe the feedhorn is actually only able to see something less than the full width of the dish (although a pretty significant part of it still - this is one of the deepest dishes made, or so I'm told, so an inch isn't as significant as it would be on a shallower dish) and moving the scaler ring helps focus it in on the part it can see.
Anyway, I say all this to say that first of all, I was not real impressed with the dealer who first installed the dish - he probably figured it was a piece of junk and that if I could get a picture at all I should be happy. But just a little bit of tweaking made a big improvement. And second, maybe the dealers have spectrum analyzers in your neck of the woods, but around here they seem to use more primitive methods. Anyway, I personally think that's not really necessary for most homeowner installations, but if you do, you obviously can afford to. I happen to like the idea that I know enough to tweak my own dish and actually gain some improvement (and learn a little more every time I do it) but for the folks who just want to watch TV and can afford to have someone come mess with it, all I can say is that I hope your guy is better than the one who set this up for me (funny thing, just a few months later he was out of the business - now as far as I know there is no one here in this small town that does installations).
11-24-2004 11:36 AM #6
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4DTV DSR922 HDD 200 VC 2+ GI2500R VC 2 Pansat 2500a c/ku/dbs feed Norsat 5215 C-band Norsat 6606a Ku-band Lnbs 10.6ft Clearview mesh AMC-8 to AMC-12 24" Venture arm.