Help Identifying Dish

[kb2kir]

Hey Guys,
I have a General Instruments A12-10C dish. I asked about this once awhile back, I figured I'd try again..... The dish measures 51" Vertically, and 47 " Horizontally. A web search yields no information.
It was supplied with hardware, support arms and mount. The price was right FREE! What I'm asking is, does anyone know where I can get the specs, or how to calculate the focal point of this dish?
The configuration of the feed supports suggests this is an offset fed dish.
I've noticed this very dish on gas stations.
I have made a set of brackets to mount an LNB to it, and had it fixed on G10R.
It worked with low signal quality until Monday, when I lost it.
I've adjusted and tweaked 'till I went crazy but still can't get G10 back.
I don't know if the $7.90 LNB died or atmospheric conditions have degraded the signal below the threshold required.
I do know this: the LNB cannot be at it's optimum location as installed be me as I SWAGed it.

 

[turbosat]

Have you tried looking at daveswebshop to see if he has anything like your feedhorn support arms need? Last time I checked there, he had the lnbf and lnb-hardware for connecting to sev diff dish types. Fort Smith - Van Buren Arkansas Hobby Shop Store
There's prob other places to look but that's the first one I could think of, that advertised that type of hardware.

 

[gabshere]

you have a picture of the lnb and the dish that might help

 

[kb2kir]

Here are the links to some pics:
www.nauf.org/000_0388.JPG

www.nauf.org/000_0389.JPG

www.nauf.org/000_0391.JPG

 

[turbosat]

Did something move and you lost signal, or the lnbf went out? I bet that dish would get
great fta signals. Did you try twisting it on the pole a little bit to the east and see if it would pick up anything on 121? Thats a pretty strong sat, try blind-scanning it and find out if you get anything. If you can, then at least its not the lnbf. Any trees in the way?

 

[gabshere]

i bet the feedhorn i have will work with it

 

[colbec]

While there may not be specific information for the dish, there are quite a few efforts to establish the proper location of the lnbf by measurement and calculation. Since it is a used dish this might be a preferred approach since you could establish the integrity of the dish, although it looks like a really well built reflector.

There might also be a method of establishing the fp in an analog manner by mounting a laser light pen on a rotating source like a bike wheel, and bouncing the laser beam off the dish. As you rotate the bike wheel light source the reflected beam should help narrow down the focal point. I wonder if this has been tried before?

 

[kb2kir]

Back to my original post, I can get 121w and another unidentified sat further west of it.
I raised the dish pole 3 feet by welding on a section this morning.
I have a straight shot between 2 trees to that area of sky. Where is G10?.
I have been adjusting for 2 hours, and cannot get it. I am blind scanning as I write this and getting channel 1,2,3 and 4 on whatever sat this is..., but no other programming.
Any clue???

 

[turbosat]

Have you checked your pole since you 'welded' an extension to it, to see if its still plumb? Got to check it well, check all around the pole with the level - digital is finicky and if its not plumb you will pull out your hair trying to track the arc.
G10 is at 123W to answer your question. Turning your antenna mount on the pole, it will be a very small amount , like 1/4 inch from where you are getting 121. Maybe even less. Takes patience to find 123.

 

[kb2kir]

Yo Turbosat, Whats up....
The dish I am using has no Az-El markings. (Makes aiming interesting)
In this case the pole can be off plumb it just gets taken up in the adjustments.
When I got it originally, I was like a kid with a new toy, I mounted the LNB you see in the pics, and just set it on the ground using a cement block and some scrap wood under the mount to set the elevation, then used another block
of wood to keep it from rolling away. It was literally sitting the ground, 50 feet
from a window in the tree line. Went inside, did a blind scan and had 10 or so channels on G10.
This was about a month ago, since then, I dug a hole out near the tree line and planted a pole in cement. Mounted the dish there, and all was well until the 4th. Since then I have been pulling my hair out trying to get it back. I thought maybe weeds or trees, so I extended the pole 3 feet. To clarify, I have a clean shot to G10 over a mountain. Using a digital angle finder, I shot a line at 21.8deg. and was miles above the mountaintop. I tried the cable on a different dish and it works. Plugged it directly into the Coolsat, I can get 121 and a sat that yields channels 1,2,3 and4. I don't know what one that is.
I have read that G10 is going tango uniform any truth to that?
Maybe I am chasing my tail trying to get weak transponders??

 

[Larry1]

A dish that size should give you a very strong signal. Have you skewed the LNBF? You are in New York? then the skew should make a great difference. It is not apparent from your pictures. A quality LNBF is important. Adjusting where the LNBF is mounted can improve the signal as well. From the picture it should be mounted on the center line of the dish and not to one side or the other. Since it is an offset dish, you will have to experiment with moving it up and down some as well as closer and further away from the dish. If there is a bracket there where the original LNBF mounted, it can give clues to the angle (or what spot) of the dish the LNBF points at. Your picture appears that the LNBF is mounted slightly to one side. (may just be the picture)

 

[Anole]

check list

It's really hard to tell from the one picture just how you put the LNB onto the dish arms.
Maybe you could post three or four more pictures from different angles, with close up shots of the LNB and arms, in relation to the dish.

First thing that comes to mind, is the skew of the LNB.
Can / have you twisted it to optimize reception of your 121/123 bird?

Second thing, and the reason I ask for more pictures, is this...
Do you have the ability to move the LNB closer and farther from the dish?
If so, give that a try while aimed at one of your weak signals.

If those are the mounting arms that were made for your dish, it looks like you probably have the LNB is about the right place.
That's just my opinion, based on looking at a lot of Primestar dish pictures here at SatGuys and all over the 'net.

You can look at the dish and determine if it's warped.
Too late to lay it face down on a floor , but you can do the string test.
Tape a fairly tight string from top to bottom down the middle of the dish face.
Tape a second string across the middle of the dish from left to right.
The two strings should touch.
Leave those in place, and add two more strings in an "X" pattern.
All four should be touching at the center.

Corroded cable connections, feedthroughs, wall plates, surge suppressors should all be checked and bypassed.
If you can see a strong signal on any bird with your LNB, I'd assume it's okay.
But if you have a spare, by all means try a different one.
The dish is beautiful, and from the pictures, I cant imagine anything wrong with it.

Well, those are a few thoughts.
Give 'em a try and see what turns up.


edit:
Looks like I diddled around too long writing my tome and Larry beat me to some of the better ideas.
Way to go, Larry !

Well, it just shows we both saw the same things.
So, that's a hint - look into those common things first !

 

[kb2kir]

Ok, I got frustrated and pulled the dish from the mount, I set it up like I did when I first got it ( cement blocks, scrap wood and shims . I'll be an SOB, it works!
65 to 70% quality!! 20 Channels
DUH???????? ?????????????????????????????????????
I believe my daughter would text WTF.