New project-Primestar to polar mount

[turbosat]

Ok I hope there's a how-to upload pictures FAQ somewhere here, since I never tried.
Tomorrow I'll try to catch some pics of what I'm doing.
1.0M primestar to polar mount , finally got started today, nice temps for a change.
The mount I'm using is for a Winegard 7.5 dish, was prob super dish in the old c-band days but I find it doesnt have the size to reject adjacent c-band channels anymore. Since it was a spare (parked on amc6-Nasa) anyway, I yanked the dish off today, and had a welding shop cut a piece of 1/4 flat steel plate to put on the front of the mount.
They burned some holes for me too, since my chinese drill is no good, and it bolted down good and flat. Took stock primestar mount off back of the dish and drilled holes to match into the steel plate, that part is flexible since I may have to skew entire dish, to make it work right. Right now I only have it tracking AMC4 to AMC-whatever at 105degrees, thank you echostar for the linear sat test channel on vertical!
I got dark just as I was making progress, so that's all so far. I do not think it is tracking the belt properly though, so tomorrow between meals I will adjust the east-west a bit, and see if I can pick up both ends of the arc.

 

[Anole]

I'm anxiously awaiting pictures.
Though, you did start with a real mount, so I know you'll be victorious.

I'd given some thought to how hard it might be to weld up some bedframes into a polar mount for a 1.0, or preferably 1.2 (dare I hope for a 1.6?) meter dish.
When I get a dish, I'm sure I'll find the motivation.

Meanwhile, post those pictures.
I need the encouragement!

PS: clever idea making slots in your plate so you can skew the dish after the fact.
I hadn't thought of that.



For attaching pictures, when you write your post, just scroll down below the Submit Reply and Preview Post buttons, and . . .
click on Manage Attachments.
It's all a smooth ride from there.

 

[turbosat]

Cool, thanks for the posting-help.. Didn't make any slots for adjusting the skew just yet , just started where I thought "close" would be. I can always drill more holes, this thing is 25" square and only need about a 10" square for the final holes (always go for more than you need)
I'll try to get this newfangled digital camera working tomorrow.

 

[turbosat]

Some more progress today on the project>got the sucker tracking most of the arc, but west of AMC1 I get nothing, and have not figured it out. By just adjusting the skew by turning the lnbf as needed, I was able to get both polarities on this 1m primestar from AMC4 to AMC6. Forgot about that weird skew setup on amc1, lost an hour trying to figure out why I could get Pentagon so great, then almost lose AMC4 every time I moved dish east lol. Once I set the skew normally for the rest of the birds, and got the east/west close and elevation closer , it really does a good job. Quality readings in the 60s and 70's on IA5, never got that one so good.
Couple of pics, it was getting dusk when I realized I was not pushing the shutter button on the new camera and only had stored one shot from lunch. RTFM haha
Next I will have to figure out where 121 and 123 are hiding, and why, then drill new holes to the metal plate to skew entire dish and leave lnbf at zero.(That is the proper way to do it-I think....)
Pics are the 1m, with the .90 in the background, and a 12' darkstar behind those. Big dish is parked on G5 for the law and order addicts here, which I am not.

 

[Anole]

beautiful mount !

Remember, your offset dish is looking up about 22º above where it would look if it were a prime focus dish.
That mount is made to work with a prime focus dish.
So, the best way to get your arc-tracking under control, is to . . .
...tilt the dish forward (down) about 22º !
That means there should be a gap between where the top of the dish attaches to your beautiful mount.
There should be no (or minimal) gap where the bottom of the dish attaches to the mount
And by "mount" , I mean that ring on the recycled C-band antenna-holder.
(get the manual and verify the 22º, and then get an inclinometer and dial in that difference between your big O-shaped metal ring and the metal plate on the back of your dish)

Then, follow the instructions for aiming any prime focus antenna (regardless of band).
When you set skew to 0º on your TS bird, it'll track skew across the sky.
Man, you are this close! :up

Oh , and props for the vice grips to rotate the "motor". !


edit:
Oh, and just to clarify... set the mount so the big O-ring is aimed as high in the sky as it goes (top of the arc).
Adjust the dish on it's hardware so a level laid across the LNB-holder arms says "level"
Then, dial the LNB to zero (no rotation).
Do this first, then you should have little or no trouble with the rest of the steps.

 

[turbosat]

That old rusty crank has been around over 15yrs!! laying on the ground , in the rain (back when it used to rain) . Fill it up with oil to stop the sqeaking and it just keeps working.
I was thinking just by raising up the elevation bolt it would take care of that extra 22 degrees, but I believe you may have something there with that 'forward tilt'.I will devise a method. Bolts, spacers or something. And then fix the skew, order a new motor etc.
ps -I was watched by 3 anoles most of the day , cock their heads and think "IDIOT" when they see me standing in the sun

 

[Anole]

Well, if they knew anything, they'd be thinking, "lucky sucker!"
Hope you didn't scare 'em away.
They eat all the little bugs.
Assuming you have enough water around to keep the bugs alive.
Might put some water on your bushes from time to time - keep those lizards happy!

 

[ftarock]

No, raising up the POLAR MOUNT elevation WILL NOT take care of the off-set degree. The O Ring is still palarell to the dish. You will need to find a way to tilt the dish forward, this offset degree is between the O-Ring and the offset dish.
You can adjust the declination at the max but still not enough for 22nd degree or whatever the offset degs is for CM dish.
My suggestion is take the dish down, do not try to tune it modification is not right, no matter what you try, it will not track the arc with the current modification.
good luck

That old rusty crank has been around over 15yrs!! laying on the ground , in the rain (back when it used to rain) . Fill it up with oil to stop the sqeaking and it just keeps working.
I was thinking just by raising up the elevation bolt it would take care of that extra 22 degrees, but I believe you may have something there with that 'forward tilt'.I will devise a method. Bolts, spacers or something. And then fix the skew, order a new motor etc.
ps -I was watched by 3 anoles most of the day , cock their heads and think "IDIOT" when they see me standing in the sun

 

[caddata]

...Remember, your offset dish is looking up about 22º...

Anole hit on the head, you need to build the dish offset angle (varies with what dish you have) into the adapter plate. The polar mount usually doesn't have enough declination adjustment to allow for the extra 22 or 23 degrees.

Fix the problem by:

(1). Someone versed in sheetmetal could easily bend the adapter or you could fabricate a wedge to correct the angle.

(2). Longer bolts with spacers (flatwashers) could be used between the dish and the mounting ring clips. That might look strange because of the distance required.

(3). The clips on the polar mount ring (that attach to the dish) could be lengthened or, even better, made adjustable if you weld or can hire a welder.

Harold

 

[turbosat]

SO, what everyone's saying is, if it's an off-set dish - make it look like one lol. Makes
sense. Since I have the elevation bolt cranked out so far, what I need to do is find
those extra degrees either in a longer delination bolt, or a modified 'spacer'.
Ok, back to study a little bit more.
Thanks guys, this helps.

 

[caddata]

....I have the elevation bolt cranked out....

If the dish that gave up the polar mount came from your area, the elevation bolt should never been changed. You still want the axis (bearing centerline) boresighted on Polaris (tne North Star). All you have to do is adjust the mounting between the polar mount ring and your offset dish to the angle of offset that your dish uses.

Harold

 

[turbosat]

Harold=the dish was in use but parked on amc6 cband for nasa (cedar tree in the way for my 10' to see that far east)
I had tried this before and like yesterday, it would track from about amc1 to amc6 very well, but no farther west. Today I played some more with the long elevation bolt and the declination adjustment has a lot of length to play with too. I finally found G10 with it, but now it wont see anything east of echo 7. Just wondered if I could find it, and get super signal strength with this dish.
Going to the hardware store later and get some parts to fashion an adapter of sorts to add the xtra degrees of declination, then I think I can set the elevation back properly.
This is an educational event lol. I didnt know 119 had any transponders a linear lnb can see, but it scanned in 25 or so from 11989 and 12080. Of course all scrambled and no ID slate I could find.

 

[ftarock]

You CAN'T crank up Polar Mount elevation to compensate the offset degrees for the offset dish.
Regardless the dish type (prime focuse or offset), the polar mount elevation is the same. What you have to do is the make the dish tilt down, this is between the O Ring of the Polar mount and the offset dish.
Good luck

Harold=the dish was in use but parked on amc6 cband for nasa (cedar tree in the way for my 10' to see that far east)
I had tried this before and like yesterday, it would track from about amc1 to amc6 very well, but no farther west. Today I played some more with the long elevation bolt and the declination adjustment has a lot of length to play with too. I finally found G10 with it, but now it wont see anything east of echo 7. Just wondered if I could find it, and get super signal strength with this dish.
Going to the hardware store later and get some parts to fashion an adapter of sorts to add the xtra degrees of declination, then I think I can set the elevation back properly.
This is an educational event lol. I didnt know 119 had any transponders a linear lnb can see, but it scanned in 25 or so from 11989 and 12080. Of course all scrambled and no ID slate I could find.

 

[turbosat]

You CAN'T crank up Polar Mount elevation to compensate the offset degrees for the offset dish.<>quote

Hehe, thats what I did, but that's why it wasn't working exactly right too. That's why I called it a project, to find out what works and why. I think I found a solution a few min ago, tomorrow I should find out. Thanks for the info!

 

[Tron]

I think the wedge between the O-ring and the dish would probably be the best idea, I'm thinking some kind of metal bars to offset the dish from the O-ring. You'd use longer ones at the top of the O-ring and real short ones (or none at all) at the bottom. Of course, you'd use an angle finder to set the offset angle, and you'd have to be pretty accurate.

 

[turbosat]

What about the declination thats already set? Does that get added to the 22degrees, subtracted from it, or not even considered? Rain was coming (FINALLY) here this afternoon , so I didn't get started working on this very well until I had to grab power cords and tools and run!

 

[turbosat]

Here's a few more pics of today's damage. The Directv AT9 dish I was given had to
be disassembled partially, I decided this mount would work for holding the dish to my polar mount and also allow the needed declination. That AT9 must've been made to
military specs, it is the sturdiest dish construction I've seen in dbs equipment. That last pic shows how it will sit when bolted down, that front-plate angle on it was about 84 degrees, more or less the max it is going to do, as is. That was with my c-band looking due south, and the elevation corrected back to 33.7.
Edit to add > This thing will also skew the dish!! by loosening 4 bolts and twisting.

 

[turbosat]

Ok I have this thing halfway tracking the arc now, with this new DTV part bolted to the steel plate. Still I have not figured out the trick to the skew. If I put the lnbf at ZERO and then turn the dish-skew plate on the mount, I don't get very much. On IA5 if I turn it all the way CCW and then CW, get nothing. Put the lnbf skew over to about -30 and I can get 69-70%quality on the H side, but nothing on vertical. Run the dish over to G10, and same thing, tuned for highest quality on V, get no horiz, and vice versa. I'm puzzled and wonder if these off-set dishes can really track right from a polar mount.
Do these diseqc-motors skew the dish more as they move east and west?
I'll work on it some more Monday and experiment some with it. Gets great video , on what it gets so far.

 

[Wescopc]

The axis on either mount (motor or prime focus) are set exactly the same ie. parallel to the earths axis (north/south). Skew should be the same.
Bob

 

[turbosat]

Sounds logical, I still have some minor additions to make, my add-on mount is right now just giving me enough to get that 22degrees, have to give myself a few extra degrees to play with. "Skew is the same" ? I'll figure it out tomorrow I guess.
thks