Invert dish for 5.8 degree elevation?

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TiminMb

SatelliteGuys Pro
Original poster
Sep 10, 2005
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Winnipeg, Manitoba
Doing a little mock up of my dish and mount in the garage before going up to mount it on the roof. There's no way I can swing an offset dish far enough down to catch 5.8 elevation. The dish hits the pole. And because I'm mounting it on a high pitch roof that slopes south, I can't angle the pole other than North / South which is useless. So does it make sense to invert the dish and end up with the dish being around 20-25 degrees back from vertical to aim it at 5.8 elevation?
 
Invert it as in hang it upside down or change the arms orientation, the pan itself upside down? If i were you, I would simply change the foot to move east / west. There is no reason you can not do this. While i understand it's importance and have done many strange installs on all sizes of dishes, for the foot to be level.. it actually does not have to be level at all. I would orient the foot downwards in the direction you need to and use this for offset. High pitch or not. Simply adjust it up and down and tweak it to get a lower angle. I hope that made sense...

-B
 
The roof slopes towards the South. The satellite I want to get is at a compass reading of 107 degrees. So its really easterly facing. I can't figure out how to slope the tube mount towards the East at all to get clearance to have the dish slope down. Options I see are sloping the tube North, South or have it vertical.

I was going to put the whole dish and its mount on the pole upside down. Now with the arm on the top, I should be able to lean the dish back at around 15-20 degrees and get a low satellite at 5.8 degrees.

How do I change the foot to move east/west as you say Bountyhunter?
 
You would have to take the foot off and re-attach it to the roof. Easily done. Do that and push the mount more forward then "level" is. You may need to turn the foot 180 of the first attempt does not work. If you have tilt on that dish you could offset for any wierd angle the dish ends up on. Use a dish 500 for example from the E* world. Basicallt as opposed to the pole going north and south you turn the foot to make the pole go east and west. Push it past where you would normally level it and there you have your extra few degrees. You will of course need a lot of luck or a signal meter to find what you want then.
 
Tim
Just flip the whole dish assembly upside down as you originally planned. That will work and give you the clearance. Unless you want to put more holes in the roof :)
 
If I'm pointing the dish extremely east, which way do I rotate the LNB for correct skew? Is this reverse if the dish is upside down as I plan?
 
twist 'n shout

If I'm pointing the dish extremely east, which way do I rotate the LNB for correct skew?
The usual way: the east side down.
From behind the dish, looking at the face of the LNB: twist the LNB counterclockwise.

If you were pointing extremely west, then the west side would be down.
From behind the dish, looking at the face of the LNB: twist the LNB clockwise.

I find it easier to envision, if I think of using two LNBs or a Twin LNB.

Is this reverse if the dish is upside down as I plan?
NO.

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Thanks everyone. This will be tonight's project. If I can't get the skew in the right ballpark, I'll be hunting for the satellite till the stars come out.
 
Yeah that should work too. I wasnt sure what you meant at first, but flipping the dish by undoing the skew bolts and re-attaching it upside down would work too. Will look interesting, but will work. You will definitely need a meter to try it.

-B
 
Wish I had a meter. I wait until I can get an assistant inside watching the TV, and I use walkie talkies to have them give me some feedback. A little cumbersome, but its worked in the past. I should have bought one of those little b/w tv's for $15.00 when they were on sale.
 
Tim
I assume you're aiming for Hispasat :)

Use the 12172 H 27500 TP to lock it. That is one of the stronger TP's :)
 
Tim
I assume you're aiming for Hispasat :)

Use the 12172 H 27500 TP to lock it. That is one of the stronger TP's :)

Yep, that's my target. Up on the roof it looks like I have a clear shot at it, and 5.8 degrees elevation is actually higher off the horizon that I thought. I wish there was a way to do a temparary mock up on the roof to see if it works before I drill any holes. 107 degrees azimuth is the direction from here. Hopefully my sightings with the compass are correct within the magnetic declination so that I truly have the window I believe I have. I've had no luck with motoring the SG2100 over that far. 73 degrees turn must be too much for it. if it works, I'd rather not have to motor over that far.
 
I'm having a tough time estimating the elevation of the inverted dish. What do you think the offset would be on a 33" digiwave dish? If its 24.5 degrees, that means when I flip it over, I need to decline it 30.3 degrees to get 5.8 degrees elevation, right?
 
oof...donot know the answer to that one (sorry)

if you can see the signal screen, what I do is get in the vicinity. My Fortec & Pansat the signal strength jumps when I'm near the satellite and really jumps (like to 90+) I know the elevation is off but I'm very near the satellite I need :)
 
Typical offset angle of these antennas is between 22 and 25 degrees,
depending upon the manufacturer. Let's assume 25, add the 5+ degree
elevation. Tip the antenna upside down and set the reflector so that it
is approximately 30 degrees (25 + 5) back from vertical.

For Hispasat, set your LNBF so that the F connector points about 50 degrees
Clockwise from the 6:00 straight down position. (around 7:45 clock angle)
...as viewed from the front of the dish.

The Cuban mux at 11884-V is probably the strongest to use for initial alignment.

An in-line satellite tuning meter would be quite useful, simply to detect the
presence of a strong satellite signal as you are waving the dish east and west.
I assume that you have surveyed for a clearance (no trees) of at least 5 degrees
elevation in the desired direction.

Good luck,

Mike
 
...

For Hispasat, set your LNBF so that the F connector points about 50 degrees
Clockwise from the 6:00 straight down position. (around 7:45 clock angle)
...as viewed from the front of the dish.

I am out by 90 degree then on my skew. I rotated it clockwise as viewed from behind the dish. OOOOps.:eek:
 
This ain't going too well. Put the zero notch of the xtreme II lnb at the top. Turned it clockwise about 45 degrees (viewed facing the upside down dish). Started at 35 degrees elevation of the dish and slowly panned back and forth. Lowered the dish a degree at a time until I got down to 25 degrees. Naddda. Must be those trees. I need a transit or something to accurately measure elevation. Too hard to do with an inclinometer. Close to giving up on Hispasat 30.
 
Align with a compass and level

I'm sure you already did it a dozen times, but I just reconfirmed all your numbers and angles.
What I like to do, is get my azimuth dialed in, then raise and lower the lnb to look for my bird.
I've always had pretty good luck getting the dish aimed right.
And I like using a $10 meter, turning on 22khz tone if necessary.
But do consider that the dish may be twisted or the LNB arm may be off-center just a wee bit.

What I do, is take a 25¢ compass and lay it on the side of an 18" level.
Mine is an aluminum I-beam shape. On its side, it looks like an H.
Rotate the compass 'till the N needle points to N
Maintaining the needle on N, align N and S on the compass parallel to the I-beam
This is trivial to do by eye, as long as you have a steady hand.
Now the level is set exactly to magnetic N/S

Holding everything steady, rotate the compass body 'till the S end of the needle is pointing to 107
If you are unsteady, you could tape the compass at this point, but I don't.
Now, rotate the whole assembly 'till the N needle points to the N, again.
Your level will now be exactly lined up with 107.

Using the long (18" in my case) level, it's easy to see if your dish is pointed correctly.
Alternately, you could sight along the level and find a distant object for future alignments.
I have a distant power pole I use for one of my dishes.
Do the above procedure several feet from any metal that would attract the compass.

BUT MORE IMPORTANTLY, hold the level -level-, sight along it and look for an interfering building or tree!
You should be able to see if you have a problem using this technique.
I don't have a $200 professional instrument for this job, so I improvise.
If the ancient Egyptians could align multiple pyramids to a degree or so, we can surely do as well ! :up
 
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