Focal distance on Prodelin 1.0 meter dish?

[Mr Tony]

Tried tonite to see if I could get ANYTHING with the 1m dish

Rigged up a LNB holder (since I dont have the actual one) and aimed near true south. I figured with 89,91,93,95,97 all near same elevation I should get something. Tried for a while and best I could lock was DBS 91 at a 75 quality with a DirecTV LNB

Tried KU and got CCTV on 95W at a 40 quality max. I'm thinking the LNB is not positioned right

Can someone with a 1m prodelin dish measure how far from dish to LNB it is?

Here is the pics of the dish
http://www.satelliteguys.us/satelliteguys-classifieds/185199-fs-1-meter-primestar-dish.html

 

[gremlin411]

I can not tell the focal length. But I put a degree finder on the bottom support of my 1.2 meter when I put the C-band lnb holder to try and get it as close as could. The angle was 50 degree's. I hope this helps you......

 

[cruzin]

would it be the same as my 1.0 channel master? if so I measured through the center of the lnb on the plane it takes to center of dish and it was 27 5/8". Hope this helps.

And that hit somewhere up in the 4 bolt area where the bracket bolts to the dish.

 

[Auric]

My ASC Signal dish came with a round support arm. I changed it to a 1/2" square tubing to accept a wider range of LNB holders, especially the 65mm. I made it adjustable so I could move it in & out for fine tuning. I did take some pics, I'll get them posted later. The hard part for you will be to get the angle at the end of the support right. You can do this by purchasing a little$5.00 laser pointer from Wal-Mart. I think the focal point will be trial & error. I'll measure my 1.2 & perhaps others can measure there's if they are the same, then the one measured by cruzin should theoretically be the same as yours.

 

[pendragon]

If this is the same dish as in the picture, the LNB mount may be too high (kind of hard to tell, though). Normally on an offset, if you take a line perpendicular to the bottom of the dish face, the center of the LNB mouth should be somewhere on that line. Of course it will point to the 'apparent' center of the dish. I say apparent because it is from the perspective of the LNB and this point will be lower than a linearly measured center.

 

[Mr Tony]

pendragon
yes its the dish in question. I picked it up from Jullius over the weekend

 

[Mr Tony]

I can not tell the focal length. But I put a degree finder on the bottom support of my 1.2 meter when I put the C-band lnb holder to try and get it as close as could. The angle was 50 degree's. I hope this helps you......

would it be the same as my 1.0 channel master? if so I measured through the center of the lnb on the plane it takes to center of dish and it was 27 5/8". Hope this helps.

And that hit somewhere up in the 4 bolt area where the bracket bolts to the dish.

Thanks guys for the info. I'll take some measurements today and see where that puts me

 

[pendragon]

If all else fails you could measure the dish depth from a string stretched from top to bottom, say every 4-5". From that I could fit the parabola and calculate the focal distance, f/D, offset angle and LNB pointing angle. I already did this once for linuxman on his 1.8m Prodelin, as I recall, and it got things in the ballpark.

 

[Larobpra]

Someone had some pics a while back where they used stick on mirrors placed on the dish to find the focal point. Anole or somebody could probably point you to it.

 

[Junito]

i'm in the process of experimenting with a 'minibud' on an offset... i still trying to figure out the focal point... but i found an interesting visual method i'm eager to try... maybe will work for you..

Visual Method-
place 1or2 inch diameter mirrors in the rim of each quadrant of the antenna... point to the sun... and where the four sun reflections meet that will be your focal point. (i suggest for precautions taping some type of cardboard to lnb no to get damaged by the sun)