Multi LNB questions

[SATire]

>Your going to have a hard time with Retro TV on 83 w if it's off from center quite a bit.
>That is a tough transponder to catch here are two of my setups, just to let it known

I get it nice and clear on my 90cm dish. Problem is that the dish is motorized so wind takes it off signal and needs adjustments too often.
89W seems to be where many live news feeds I was seeing on 97W have moved so 89W is more important to me. That would make my main choices being 89W and 97W, anything else would be a bonus.

>Last word of advice I have for you is a 120cm will help you quite a bit

A 39" is pretty much the biggest dish I can imagine going up there. This is a roof mount otherwise, I'd have gone bigger dish. I'm doing the roof mount simply because I have a very beefy Starband mount left over so figure I'll take advantage of it.

 

[SATire]

>If you want to guarantee success, pick up a toroid dish like the Wave Frontier T90.

I'm torn at this point. I want to get this thing up before the cold weather sets in and I just know it'll be a pain to get this working.

 

[SATire]

From what I'm reading, it sounds like even using the round dish, I should be able to get two satellites and maybe even a third later at some point.

As for the lnb bracket, another suggestion is that I mount it so that the lnb's are as far away from the dish as possible, or, am I misunderstanding this? I could probably extend it out further through a little fabrication.

I will see if I can do something with the mount that is already up there since it does have skew. I might be able to fab something up so that I can put it to use.

I'll know tomorrow once I look at it.

 

[Keith Brannen]

From what I'm reading, it sounds like even using the round dish, I should be able to get two satellites and maybe even a third later at some point.

With a 39" dish, you should have no problem getting 89, 97 (at centre) and 103 on the dish. I have had that setup before on my 80cm. I only moved 97 off-centre to move 103 closer to centre to gain a bit on the NBC muxes (which I did get at 6 degrees off-centre, but wanted to boost the signal to get extra leeway). Your 39" dish probably will have enough signal that you wouldn't have to do the move I did.

As for the lnb bracket, another suggestion is that I mount it so that the lnb's are as far away from the dish as possible, or, am I misunderstanding this? I could probably extend it out further through a little fabrication.

Other way around. Off-centre LNBs have to be closer to the dish than the centre LNB (think of the focal point as a mirror image of the dish curvature, the focal distance is constant from the centre of the dish to all LNBs). Therefore, the straight bracket pulls the LNBs away from the optimal focal point. If you are doing 8 and 6 degrees off-centre, by pushing the LNBs forward in the LNB holder you should have no problem, experiment for the correct distance. Also the LNB face is angled slightly towards the centre of the dish (again along the mirror image of the dish curvature). Again, experiment and you'll get the hang of it!

I will see if I can do something with the mount that is already up there since it does have skew. I might be able to fab something up so that I can put it to use.

Don't waste your time on skewing the dish. For starters, I have had excellent results all along the arc with multiple LNBs on round dishes. More importantly, with 93 as your true south (top of the arc) there is very little skew involved (in fact two of the LNBs are on either side of your true south), and I doubt you would notice much (if any) difference if you did try and skew the dish.

 

[SATire]

Since you are close to the top of the arc with these satellites, your adjustments up and down will be slight, and other than my 75e and 60e dishes, all others are "round" dishes and I've had good success across the arc. The advantage of a skewable (elliptical) dish is that you can place LNBs farther away from the centre of the dish and not experience as much loss as on a "round" dish. But when you are talking about 6 to 8 degrees off-centre, the loss will be minimal, especially when you are close to the top of the arc.

It dawned on me last night that using a round dish, skew won't have any value will it.
I'm guessing the bracket on the other hand does need to be very flexible and it certainly looks it.

 

[SATire]

>Don't waste your time on skewing the dish. For starters, I have had excellent results all along the arc with multiple LNBs
>on round dishes. More importantly, with 93 as your true south (top of the arc) there is very little skew involved (in fact

I'll try and get everything up there today, using 93W as my starting point. I'll make sure my arc is good and go from there.
Good to know I don't have to worry about skew after all.

 

[Keith Brannen]

I'll try and get everything up there today, using 93W as my starting point. I'll make sure my arc is good and go from there.
Good to know I don't have to worry about skew after all.

Only skew you need to worry about is skewing the LNBs (which won't be much, except if you try for 103, then use the same skew as you would use for H2 (73)). Good luck!

 

[SATire]

Don't know if they sent me the wrong dish but it's an offset, not fully round after all.

 

[SATire]

The dishpointer site says my elevation is 38. I don't have a motor on this and it is an offset dish. Do I still go with 38?

Latitude: 45.1367°
Longitude: -92.9900°

Name: 93.1W GALAXY 25 (G-25)​

Elevation: 38.0°
Azimuth (true): 180.1°
LNB Skew [?]: 0.1°

 

[brentb636]

Yes, declination angle is for motor correction.

 

[brentb636]

Don't know if they sent me the wrong dish but it's an offset, not fully round after all.

A Ku dish is always offset. It's a subsection of a larger parabolic dish ( prime focus) , which IS round. People just think Ku dishes are "round" until they measure them vertically and horizontally.

 

[SATire]

Ah, ok, so how do I find out that I need for elevation now? My 6' dish is something like 57 if I recall. I think I have notes somewhere but I'll ask here while I look in case someone replies so I can get back out there. Darn windy day no less. Kinda interesting to be on the roof with a 39" sail . It's mounted at least so that's done.

 

[SATire]

Now that I have it on the roof, I'm not sure I'll be able to even see 89W due to the roof being in the way. The old mount was for a dish pointing to 123 or such I think. If I do, it'll be soooo close.

 

[SATire]

Quick question to all... can I put a stick across the bottom/top of my 90cm to get the angle then just set my new one to the same?

 

[Keith Brannen]

Quick question to all... can I put a stick across the bottom/top of my 90cm to get the angle then just set my new one to the same?

As long as the LNB offset is the same for both dishes, it would work, should get you close anyhow. The dishpointer value (38) would be the one I would go with, and then adjust from there, as sometimes the dish scale is not always accurate (my Fortec Star dishes, IIRC, all seemed to have to have an extra 3-6 degrees added to them to get the peak signal).

 

[SATire]

No luck what so ever finding any signals so far. The receiver doesn't react quickly enough so floundering around looking for signals is not doing a thing.

I really do have to get a meter for this.

 

[Keith Brannen]

No luck what so ever finding any signals so far. The receiver doesn't react quickly enough so floundering around looking for signals is not doing a thing.

I really do have to get a meter for this.

Which receiver are you using? I learned my lesson (after a fruitless search using the AZBox when just adding an LNB to an already set up dish) to use my Pansat for aiming/setting up, and then use the AZBox for fine tuning of the S-2 signals. A good DVB-S/non-HD receiver can be a great satellite meter (at least my Pansat is).

 

[SATire]

Which receiver are you using? I learned my lesson (after a fruitless search using the AZBox when just adding an LNB to an already set up dish) to use my Pansat for aiming/setting up, and then use the AZBox for fine tuning of the S-2 signals. A good DVB-S/non-HD receiver can be a great satellite meter (at least my Pansat is).

It's just a traxis but it's too slow to react to signals. I've ordered one of those basic meters which always worked for me before. They react instantly to signals. Once I get a signal, I'll usually use the receiver to fine tune from there. Just can't find anything at the moment. I'll get back at it when I get the meter.

 

[SATire]

Quick question. I know my due South is 93W but is that where I am fixing this dish since I will be trying for other birds?

Thanks.

 

[Keith Brannen]

Quick question. I know my due South is 93W but is that where I am fixing this dish since I will be trying for other birds?

Depends on what you have decided to try and get on the dish. If it is 89, 97, and 103, with 97 at the centre, then I would shoot for 97.