Birdveiw declination
- Thread starter rainmaker
- Start date
- Latest activity Latest activity:
- Replies 15
- Views 3K
-
WELCOME TO THE NEW SERVER!
If you are seeing this you are on our new server WELCOME HOME!
While the new server is online Scott is still working on the backend including the cachine. But the site is usable while the work is being completes!
Thank you for your patience and again WELCOME HOME!
CLICK THE X IN THE TOP RIGHT CORNER OF THE BOX TO DISMISS THIS MESSAGE
- Status
Mount has some declination built into it. Add multiple flatwashers between back of dish and mount as required to acheive your proper declination. Longer bolts may be required to allow enough thread engagement (diameter of bolt) into dish. My dish used 3/8" bolts, although I've been told some dishes used 5/16".
I had the Birdview (hydroformed perforated) in Arkansas, before we moved to Florida. It was a great dish. Converted the HH mount to pulse so my Uniden receiver could move it, and machined the existing scaler flat and mounted a Chaparrel Corotor 2 on the stock feed. Watched C and Ku for about 5 years with no adjustments to the system until we moved in 1998.
By the way, the mount took about 8 flatwashers at the top, and gradually fewer towards the bottom.
As a side note, I had to recruit my wife for help when I installed the pole (6" sch. 40 pipe, 6 ft. above ground and 4 ft. in ground). Rented a gasoline powered auger and drilled a 16" hole in what looked like the best location in the backyard. Filled the hole with Sackcreet and formed a 3 ft. sq. slab on the ground around it. Several years later, utility crews located all the underground electrical lines in the neighborhood by spraying paint on the ground above them, along their path. The paint stripe in my yard came within a foot of my drilled hole. Gave me cold chills when I realized it. Never gave a thought about underground utilities. I can only imagine the fireworks, had we cut through the electrical line.
By the way, the mount took about 8 flatwashers at the top, and gradually fewer towards the bottom.
As a side note, I had to recruit my wife for help when I installed the pole (6" sch. 40 pipe, 6 ft. above ground and 4 ft. in ground). Rented a gasoline powered auger and drilled a 16" hole in what looked like the best location in the backyard. Filled the hole with Sackcreet and formed a 3 ft. sq. slab on the ground around it. Several years later, utility crews located all the underground electrical lines in the neighborhood by spraying paint on the ground above them, along their path. The paint stripe in my yard came within a foot of my drilled hole. Gave me cold chills when I realized it. Never gave a thought about underground utilities. I can only imagine the fireworks, had we cut through the electrical line.
The change in declination (not to be confused with elevation) over 30 miles N/S will be minuscule, bordering on imperceptible.
I would not assume that the declination is set correctly. If it had washers under it, chances are it had been peaked correctly. Birdview dishes were manufactured in Kansas and sold all over North America. The dish that I had in Arkansas required six or eight flatwashers to peak the declination. Locations north and south of there would be proportional in washer requirements.
The dish had been previously installed without flatwashers. It had been used for only C band reception and the owner probably never realized it had not been peaked correctly. Bought it from scrap pile at a local satellite shop (owner prosecuted by HBO for selling reworked VC2 boxes) and installed it at my residence. Ku band reception was poor before I peaked it. However, after peaking, it tracked Ku perfectly from horizon to horizon. That was in 1992 and it's still working perfectly - over 20 years old with the original motor in place. It survived several close encounters with tornados. That 6" post is a little overkill.
The dish had been previously installed without flatwashers. It had been used for only C band reception and the owner probably never realized it had not been peaked correctly. Bought it from scrap pile at a local satellite shop (owner prosecuted by HBO for selling reworked VC2 boxes) and installed it at my residence. Ku band reception was poor before I peaked it. However, after peaking, it tracked Ku perfectly from horizon to horizon. That was in 1992 and it's still working perfectly - over 20 years old with the original motor in place. It survived several close encounters with tornados. That 6" post is a little overkill.
What is the recommended declination angle for your latitude? If you find two different published latitude figures for your latitude, one is the declination angle to the due south and the other is the declination angle for a "modified" polar mount, which is typically half a degree or so less. I explained the modified polar mounting HERE.
I've only worked on one Birdview dish, about fifteen years ago, but you should be able to use trigonometry on the backplane to figure out how much shimming you will need for your selected declination angle.
I've only worked on one Birdview dish, about fifteen years ago, but you should be able to use trigonometry on the backplane to figure out how much shimming you will need for your selected declination angle.
Last edited:
AntAltMike:
I can't agree with all the "tilt the mast forward" statement in your modified polar mount post. The mast (post) should be as close to perfectly plumb as possible. Adjustments for elevation (polar axis), declination (latitude correction), and azimuth are then made.
Rainmaker:
Check the url's listed below for more info and graphic illustrations for the geometry. I'm not sure of your exact location, but Louisville, KY would have a declination angle of almost 6 degrees.
http://www.geo-orbit.org/sizepgs/decchartp.html
http://www.arrowe.com/polarmount.html
I can't agree with all the "tilt the mast forward" statement in your modified polar mount post. The mast (post) should be as close to perfectly plumb as possible. Adjustments for elevation (polar axis), declination (latitude correction), and azimuth are then made.
Rainmaker:
Check the url's listed below for more info and graphic illustrations for the geometry. I'm not sure of your exact location, but Louisville, KY would have a declination angle of almost 6 degrees.
http://www.geo-orbit.org/sizepgs/decchartp.html
http://www.arrowe.com/polarmount.html
When I said "tilt the mast forward", what I meant was, tilt the pivot axis forward because otherwise, if it is perpendicular to the equatorial plane, it will track a circle that is eccentric to the Geosynchronous circle, but if you tilt the pivot axis forward between one half and one degree, the intersection becomes an ellipse that tracks the arc more closely. Remember in Calculus, when they demonstrated that the intersection of a cone and a plane is an elipse ? Well, a polar mount with a declination angle sweeps out a flattened cone, but the intersection is still an elipse. I think in one of Dr. Frank Baylin's mistake-laden texts, he says the maximum tracking error of a modifid polar mount compard to a true polar mount is about one-half as much error.
thanks for the links my lat is at 38 degrees so declination would be 6.02 and no they did not have any washers installed so that's why i suspected the declination was off thanks for all the help.
i would love to buy one of the old birdview dish hth 20\20 dishes.contact me at mrmoto1164@yahoo.com complete as possible would be nice
thanks
thanks
I have a question about "built in" declination on the Birdveiw. I live in Kansas and since the dish was manufactured in Kansas, would the built in angle be close to what I need? The Birdveiw factory was at 37.67 lat and I am at 38.06, so my angle would be close to thiers.
Thanks
Thanks
I'd say, offhand, that it will require six to eight washers. Without any scientific research on my part, I believe that the built-in declination was good for the Gulf coast since they sold dishes all over the Southern United States.
Have you found an old Birdview? If so, I'd recommend getting it if you can. If it's not damaged, you'll be suprised how well it performs. They were well designed and will give amazing performance without you having to constantly peak it. The HH mount is simple but built like a "Swiss watch".
Harold
I'd second Harold's suggestion. Get it if you can. I have one, and am waiting on a home-owner's permission to get a second one. I don't need it, but can always put it in storage for a time when I might need it.
As to declination and where you live. The one I put up only required 1 washer between the mount and dish using the top 6 bolts only.
I live at 38.931N latitude. It is working great for me from 30W to 148W on both C-Band and Ku-Band. They are fantastic signal catchers, and the true H-H mount is a sight to behold. Just "like a Swiss watch" as Harold says.
Fred
Yea, I found one in excellent condition. Actually, there are two more that I found that the owners are wanting them out of thier yard. I did purchase a new motor from Skyvision (ouch, very pricey!) I set up a Birdview for my dad in 1984 and he is still using it. I don't thinkit has ever been messed with except for fixing one of the rods holding the feedhorn. I am having my brother machine the hole in the scaler ring and then I am ready to rock. Can't wait.
- Status
