Clearance necessary for 5 or 6 foot dish

[Cletus2k]

I'm considering getting either a 180cm/6 foot or if I can find one a 5 footer prime focus dish.. The main problem is the only place I can put it and get any decent exposure to any birds is to south of my shed which is very close to my neighbors/my short fence.. This location should give me visibility to 79W->135W or so.. I have my 90cm dish there now and there is plenty of room, but this is obviously going to be a much tighter fit with a much larger dish.. There is about 6.5 feet of clearance horizontally, and 6.2 feet at an angle of 50 degrees..

Attached are a photo of the area I am considering (really the only decent option on my property - live in the city) as well as a diagram with distances.. The shed wall in the diagram is directly east-west (part of the small grid part of my city).. The location I am considering is behind (in the photo) the 90cm dish where the Nandina (bush) is..

When facing my direct south satellite (79W) my elevation is 48 degrees. I think I with a 6 footer I can position the dish so that it sits below the gutter of the shed and is partially blocked by the fence but this should only be a VERY small portion of the surface area of the dish.. With a 5 footer I think it's less of a problem.. When aimed to anything further west the dish should not be blocked by anything once it's rotated away from due south.. (125W is at an elevation of 27 degrees at my location)

One question is how far behind the dish do most actuators stick out? Am I going to have a problem with the actuator running into the wall of the shed? I've seen photos but never really been able to ascertain how far behind the dish they actually stick..

When measuring a 180cm dish is that the measurement of the chord from edge to edge through the center, or is that the measurement following the slop of the dish?

Also if this does work out any suggestions on how to really calculate the math so the dish doesn't run into anything? I'd hate to set a heavy duty 3" pole in the ground and find out it's off a few inches and has to be re-done..

At this point I don't know what else to ask but hopefully someone can help me generate more questions or figure out what the largest dish i can put in that area to get some C-Band stuff is..

Thanks..

 

[Anole]

Without doing the math . . .
- a 6' offset feed dish would be more vertical, and fit your space better
- a horizon-to-horizon (H-H) motorized mount, would not stick out behind the dish like a standard jack would
- what is the magnetic deviation in your area? I assume your east-west wall is magnetic not true (probably doesn't matter but one more thing to worry about)

Unfortunately, the only readily available 6' offset dishes are heavy, and don't have H-H motors, nor even easily motorizable mounts.
I was thinking of a surplus (free) 6' Prodelin offset, on an AJAK 180 (good luck finding one) mount. -
edit: not too sure how the 52" focal length would fit your area....

Is it time to think outside the box.. maybe above your eaves on a tall pole?
That might let an 8' BUD swing along just fine! - :up
The motor could then hang over the building.
Also, people -have- put holes in their roof for a pole, so the pole is within a few inches of the building, should that be necessary.

 

[Cletus2k]

The magnetic offset is between 8 and 9 degrees.. Can't recall off the top of my head but my property line (and shed/house) are pretty much true.. Maybe off by a degree or so.. When I remounted my 90cm dish the other day the motor assembly ended up being maybe 1 degree or so out of perpendicular from the shed wall, so likely it was the best they could do back in the 1920s when my house was built..

Going up isn't an option in my opinion.. I run into some trees if I go up that would knock out 72 -90W or so... Go a further on my property you end up loosing anything over 110W I suspect..

 

[Dishman Dan]

...Going up isn't an option in my opinion.. I run into some trees if I go up...

CHAINSAW!!!

Looking in the photo I cannot see any trees right along where you are thinking of putting the dish. Would the dish be looking under a tree and that is why you cannot go up???

 

[mmewrench]

I have a 10ft unimesh set up in a little less space than you have to work with. The center of the pole is exactly six feet from the back of the house, and I dont have any clearance problem. You should be able to go at least that big. At 48 degrees the dish itself will extend further from center than the actuator.

 

[Cletus2k]

Looking in the photo I cannot see any trees right along where you are thinking of putting the dish. Would the dish be looking under a tree and that is why you cannot go up???

Yes i'm shooting under a large (30-40 foot) white pine from that location.

I can't go up for numerous reasons.

I can't afford to take any branches off the white pine as the other side gets hacked away every few years by the power company so it really needs those limbs for survival. I also don't have any interest in paying to take branches off or doing it myself as I'd have to climb into the tree at least 20 feet with a chainsaw.

If I were to take off branches on the white pine I still can't put it on the shed because the shed isn't totally structural sound and I can't imagine that it would be happy with a heavy dish on it. The sill plate on one side of the shed has been eaten away years ago by termites and needs to be replaced (Just haven't gotten to it yet). The roof of the shed also gives some under my body weight so putting a dish on it would require some reinforcement. The shed is likely as old as my house (Built in 1923) and needs some TLC. (It's not worth tearing down and replacing but it's not in the best shape currently). I already made the mistake of mounting my 90cm to the side of the shed only to find it wasn't that stable.

 

[Cletus2k]

I have a 10ft unimesh set up in a little less space than you have to work with.

I am confused. Is part of the dish blocked? If you look at the diagram that I drew putting a mount pole 6 feet from the structure would be within an inch or two of the fence. Can you post any photos or reference me to some?

 

[putney]

My 8' Unimesh is about 7' from the lower rim of the dish to the back of my 24" jack.

http://www.satelliteguys.us/c-band-satellite-discussion/212954-45-w-133-w-omg.html#post2197733

I use it in a very confined space. When pointing at 133º-139ºw, 1/3 of the dish's surface is blocked by my home.

I think a 6 footer with an 18" jack would work in you space. i would do a dry run with a temporary mount to make sure you dish can move the maximum range.



.

 

[mmewrench]

I am confused. Is part of the dish blocked? If you look at the diagram that I drew putting a mount pole 6 feet from the structure would be within an inch or two of the fence. Can you post any photos or reference me to some?

Im sorry I missunderstood you. I thought your point "A" measurement was your pole. In order for a ten foot bud to work for you,yourdish would extend into your neigbors yard quite a bit. With the polar mount at 6 ft above grade, the lowest part of the dish is 39" from the ground. At true south my elevation is 40 degrees at 48 degrees your lowest point may be high enough to clear a 4ft fence but I dont think your neighbor would be willing to give up that much of his yard.

 

[Cletus2k]

Here is a better diagram that is to scale if this helps any. I re-measured everything including the shed & fence height and eave overhang.. My angles were off a little bit before. I am fairly certain that the actuator won't be a problem given there is 20 inches under the eave. I am thinking I could have it just barely under the eave/gutter and get roughly 85-90% of the dish exposed when facing due south. When facing further west more should be exposed as the distance to the fence will change..

 

[mmewrench]

That will be a tight fit. You will have to place your post carefully and you may want to use a h to h positioner They are available from european supp;iers.

 

[guapoharry]

It's not uncommon here to see dishes way high in the air on a tall pole. That way, you could put the pole next to the roofline. - What Anole said...

Then the part of the dish that projects toward the north could stick over the roof. (meaning you might be able to have a 8-10 foot dish.

 

[nycrich]

I had the same issues last year setting up my 6 ft dish. Make/buy an inclinometer (I have a previous posting on this or do a search on the web) and coupled with a compass you can check your clearances and determine your arc. The compass is used to check the azimuth (minus declination) direction of the intended sat, then hold up the inclinometer at that compass heading. You will need to find elevation angle of the intended sats, which can be found widely on the web, Sadoun Satellite Website, or Lyngsat. Looking through the inclinometer with the azimuth heading and elevation angle from your site will allow you to determine which sats and your best location.
There is also applications available on the Iphone, Blackberry, etc (cost $$) that allows you to hold up your phone in camera mode and it will show you the satellite arc based on your location. I used Dishpointer (application) on my Iphone and was able to see my arc from 8W to 140W using different locations in my backyard. Good luck.......

 

[Cletus2k]

My question doesn't concern visibility to the arc. I have a 1m dish in nearly the same spot. It was placed using a compass and an inclinometer to find the best spot in my yard. Sadly there is NO spot that I can get anything east of 60W or so.. I know my location satellite visibility wise is a good spot. I am more concerned about the clearance necessary for a dish that large to not run into the fence / shed / gutters / etc, and specifically any thoughts on the actuator running into the shed wall, etc. For example how far back does a 24" actuator stick from the mount point on the sadoun dish? Could I get away with an 18" actuator? I am only planing on moving the dish from 70W-135W (or whatever the furthest west C Band Sat is)..

 

[Dishman Dan]

Yes i'm shooting under a large (30-40 foot) white pine from that location. ...

...I can't afford to take any branches off the white pine as the other side gets hacked away every few years by the power company so it really needs those limbs for survival. ...

...If I were to take off branches on the white pine I still can't put it on the shed because the shed isn't totally structural sound and I can't imagine that it would be happy with a heavy dish on it. ...

Up my way, when the power company "trims" a tree, it is usually better to take the whole thing down! They really mess them up bad and they are unsightly! Is this tree so slaughtered that it might be a candidate for removal??? Is it part of a landscape design or just there???

I would consider removal if it was my tree! I cannot see the whole view of what is really there so this may be a bad idea. I would then place a pole next to the shed but not on it!!! Like what was mentioned before, if you go high enough your actuator and dish can use the space above the shed!

 

[Anole]

possible H-H solution:

I'd forgotten, but Sadoun recently mentioned a small H-H motor he used to import.
It had been discontinued due to low sales.
I thought he said he got or was getting some more.
(HH-180? .. I forget the model number)

So, CALL SADOUN and ask about the motor.
If he has 'em, get the 6' dish from him, too.
It's a little heavier metal than the Fortec, and same price (as I recall).

 

[gordonkearse]

The main thing is you get the most useful part of the arc.

To me, anything below 74W is essentially useless. Maybe I'm wrong. I keep looking at lyngsat and can't see much below that.

Anything above 129W is essentially useless. There maybe two or three channels. That's about it.

As long as you have the useful region covered, you ought to be in pretty good shape. I've got my dish on top of a fifteen foot pole so I can clear eight pecan trees in my yard. It required getting the dish 150 feet from my house. I still get a good signal with good wire and no splices in the coax.

I was concerned about a utility feed about ten feet over my dish. It crosses the arc too. So far, no problem. I'm not getting any interference from it.

Somebody let me know if there are lots of other good channels I'm missing out on because of my arc.

Happy satellite hunting!!!

 

[pjcl]

Line of Sight

I'm not sure if this can be considered "thread hijacking", but I have a similar question... can any of you experienced C-banders tell just but looking at the pics if I can have any hope of a LOS on this location? Consider I am at 34.4 N. I have seen a couple of dishes around here with very steep elevations, so...

Thanks!

 

[stanleyjohn]

Lots of trees!!Just like my area.What you can get depends on your location!If your as far north as i am i think some chop!chop is due if you can.