Actual Declination adjustment??

[esteveW]

Not as easy as I had hoped.

I have my BUD hooked up to the receiver and with elevation set I'm getting only a ghost of a picture on a couple sat.s/channels. Signal is 90 but quality is 1 or 2 at best.

I set the elevation to 90 deg. - 47 lat. = 43. now I need to adjust the declination down a few degrees from the previous setting.

My mount is almost exactly like the attached drawing. I can't adjust from the bottom pivot bolt since it is already screwed in all the way. It appears that all previous adjustments were made with the top pivot bolt. There is a close up of the top bolt and it is threaded into the "long" nut welded to the dish center ring. (same with the bottom) To do any adjustment I would have to remove the pivot bolt from the eye end and rotate it out to lower the dish or in to raise it. That wouldn't be to big a deal if I had some help, but I'm doing this all by myself.

I may have to build some kind of support for the dish to keep it from tilting forward or rolling right or left. Since this adjustment will be some 'trial and error' until I get the correct angle reading, this could be tedious, at best.

Same thing if I search out volunteer help.

Maybe I mark my elevation setting and then back it off until the dish is vertical (90 deg.), block it up and remove/adjust the pivot bolt to the actual declination number. The return the dish to the proper elevation angle.

Sorry, just thinking "out loud"!

Any ideas.

Steve

 

[Lone Cloud]

It's hard to see it from your pictures. You should look at it to see if you can adjust without disconnecting the eye bolt. From the look of it, on the threaded end, there might be a nut on both ends of the plate, meaning the plate itself has an unthreaded sleeve.

You are up there in the tundra latitudes so your declination will be higher than it is in these warmer climes. Have you used an inclinometer or other device to find out the angle difference as between your dish and the polar mount (dec. angle)? If it's close, your issue may be something else. Maybe an old lnb or coaxial cable run that is too long., or even wrong settings.

You didn't mention what receiver you were using.

 

[esteveW]

The eye bolt type pivot is threaded into Long Nut or Rod coupling that is welded to the dish backing ring. That is for sure.

I just marked the pole and rotated the dish around so I could get my tractor loader under the rim of the dish. I then removed the pivot bolt and was able to get enough clearance to back the eye bolt swivel out about 3 turns. Just guessing, since I only had to go a couple degrees for the new settings.

BTW. The dish came from a site in Redmonds WA. About 60 miles north of me and about 60 east. So if the dish was adjusted correctly for that installation, my changes should only be minor. So far I have increased the elevation to my lat. which is 47. and the combine elevation and declination adjustment gives my a reading of about 37 deg. angle. (90 - 47= 43 - 6 dec. = 37. ) The dec. should have been a bit more but I did the first attempt on the lite side to see what I would end up with.

The cable is all new but I'm using the full 170 ft length since I haven't actually installed it. It is just running across the lawn and in thru the patio door.

I have an old Toshiba 1820 anolog recvier and a 905 side car that I just purchased. I'm still learning how to work both of the together. It is rather confusing and (so far) limiting. The preprogramed satalites in the 1820 list are out of date to a great extent and the 905 list only match up with about 10 current birds. I have to figure out how to program in the current birds. The 1820 give a brief procedure but I haven't found anything in the 905 manual.

Since I adjusted the dec, on the dish, I haven't been able to pick up any of the several birds I got 'Ghostie' pictures on yesterday. I must have done something wrong and hope someone can point out my error.

Steve

 

[Mauiguy]

The eye bolt type pivot is threaded into Long Nut or Rod coupling that is welded to the dish backing ring. That is for sure.

I just marked the pole and rotated the dish around so I could get my tractor loader under the rim of the dish. I then removed the pivot bolt and was able to get enough clearance to back the eye bolt swivel out about 3 turns. Just guessing, since I only had to go a couple degrees for the new settings.

BTW. The dish came from a site in Redmonds WA. About 60 miles north of me and about 60 east. So if the dish was adjusted correctly for that installation, my changes should only be minor. So far I have increased the elevation to my lat. which is 47. and the combine elevation and declination adjustment gives my a reading of about 37 deg. angle. (90 - 47= 43 - 6 dec. = 37. ) The dec. should have been a bit more but I did the first attempt on the lite side to see what I would end up with.

The cable is all new but I'm using the full 170 ft length since I haven't actually installed it. It is just running across the lawn and in thru the patio door.

I have an old Toshiba 1820 anolog recvier and a 905 side car that I just purchased. I'm still learning how to work both of the together. It is rather confusing and (so far) limiting. The preprogramed satalites in the 1820 list are out of date to a great extent and the 905 list only match up with about 10 current birds. I have to figure out how to program in the current birds. The 1820 give a brief procedure but I haven't found anything in the 905 manual.

Since I adjusted the dec, on the dish, I haven't been able to pick up any of the several birds I got 'Ghostie' pictures on yesterday. I must have done something wrong and hope someone can point out my error.

Steve

If you adjusted your elevation and declination. You will need to rotate the dish on the pole now.

Ideally you would want to go to the satellite that is nearest to due south of your location, the slowly rotate the dish until you pick up a signal. Then fine tune it with your receiver.

 

[esteveW]

Update

found I had the C and Ku leads mixed up at one junction point. I how have my Ghostie picture back with a pretty strong signal on G1 analog. Quality isn't there yet but I have a clear B/W picture with sound.

Not there yet but now I have a point to work from.

Steve

 

[Lak7]

Have you tried adjusting the Skew?

 

[esteveW]

The feed horn is reinstalled exactly where it was at the old location. I'm trusting that was correct or at least close enough to give me a point to start from for fine adjustments.

The analog receiver does a skew adjustment automatically when I set up each satellite location then does the fine tuning of the E/W along with a channel scan.

Should I do a physical adjustment to the skew?? Perhaps the 'tweaking' that is done automatically lacks the range.

Something else that I'm unsure of is the physical alignment of the scaler ring/feed horn with the focal point of the dish. My BUD has the feed horn mounted on a "Button hook" and the button hook itself precludes any direct alignment method. I'm still puzzling over this problem/question. This is the reason I have place a lot of faith on the original installation locations.

I'm looking at the Feed Horn alighment template and instructions and begining to see how this adjustment is made. While I'm at it, I can verify the f/D and maybe figure out a method to verify/tweak the Focal point.

I may have to rethink all of this. I appreciate all the comments and suggestions.

Steve

 

[Lak7]

This page may help.....
Footprints by Dish Size - Adjusting the Polar Mount for Prime Focus Antenna - C/Ku-Band Satellite Systems - Tuning, Tracking, Azimuth, Elevation, Declination Angles, F/D Ratio, Focal Distance, Inclinometer, LNB/Feedhorn Assembly, Actuator Assembly, C

This one too, use the "Modified Polar Mount" Chart
Footprints by Dish Size - Latitude Declination Chart - C/Ku-Band Satellite Listing

 

[phlatwound]

Can you measure from the edge of your dish to the edge of your scalar at 3-4 approximately equally spaced spots? This should give you a pretty good idea if your feed is centered in that direction.

If not, you might have to try to push it manually and pull it with guy wires or consider fabricating some feed support arms to carry the feed?

Also, I think you need to be aimed fairly close on an active analog transponder for that autotune/autoskew routine to work on your 1820. I believe you can override the autotune routine in your menus and tweak it manually.

 

[esteveW]

Skew and FeedHorn adj.!

I plan to do the f/D measurements today and while I'm at it I will measure from the rim of the dish. However, even if these measurement position the feed horn in the center of the dish, there is no assurance that the feedhorn face or scalar is aimed dead center on the dish.

I'm trying to figure a way to make a 'tee square' device that I can clamp to the scalar ring to, then offset the tee square about an inch to clear the button hook tube.

Thanks for the response. Sometimes I find the answers to my question and that is often a result of just sitting down here and putting thoughts into words. The suggestions contribute considerabily to this process.

Steve

 

[B.J.]

I plan to do the f/D measurements today and while I'm at it I will measure from the rim of the dish. However, even if these measurement position the feed horn in the center of the dish, there is no assurance that the feedhorn face or scalar is aimed dead center on the dish.
.....

I wouldn't worry about whether the feedhorn is aimed dead center. That has a minimal effect on reception. I've tilted my feedhorn so that it aimed about half way to the edge of the dish, and it didn't affect reception that much, and actually in that specific case it actually improved reception, but that's another story.
Anyway the important thing is that the feed is at the focal length, and if it "looks" like it's aiming at the center, I wouldn't worry about it being perfect, because regardless of the feed's look angle, it's still receiving the same sat, because it's the dish that's responsible for aiming at the sat. Tilting the feed just slightly changes the illumination of the dish, ie which part of the dish most of the signal's coming from.