Two LNBF alignment question

[Keith Brannen]

BTW Keith does your HTN channels on AMC-4 get weak at night allot? I wonder if it's weather related at the uplink since it's clear here. Wonder where the uplink is too?

Unfortunately, it does, big time. "Normal" quality for me on the Pansat (on my 60e dish, 6 degrees off-centre) is 45. It starts to drop somewhere around 4 or 5 pm EDT and continues to get worse until it is in the low teens, and, more recently, disappears completely. Currently it is at zero (clear skies here). Earlier today it was hovering between 45 and 60 (best I've seen it recently) but then gradually started to go away. Naturally, no other transponder shows any change at all.

It seems too predictable and constant to be weather related every night. Which satellite is it on, AMC2 or AMC4? Lyngsat has all Ku listed as being on AMC4, but I remembered this thread about 11860:
http://www.satelliteguys.us/free-ai...-satelliteguys-help-readings-amc2-4-101w.html

 

[tvropro]

I don't know if there backing down there power at night or what. I can gain 15 points of Q 45 to 60 if I boresight on AMC-4. It could help it hang in there a bit longer. I'm hoping to gain some of that 15 points back with the mod I'm working on. It seems that anything I want to watch on ku tends to have some issues. Equity, then RTN on AMC-9 now this. I'm glad I don't have issues with c band like this but having a monster reflector covers quite a bit of this type of stuff up. I still may have to work on getting my hands on a 6 foot solid with a prime focus ku lnbf and make it movable. I could put it where my 90cm Primestar is now since that pipe is 3"od and in concrete. Just wish I had cashflow to do stuff like back in the day. With the US economy like it is and my business down it's doesn't allow much room for making purchases for satellite toys. I have quite a wish list currently on hold.

AMC-4 is ready for replacement from what I read in your link. This may be the whole reason that there is a problem here. The bird is dying and that's that. I never seem to be affected with issues like that on c band because of overkill. My ku dishes though are not up to that caliber. Well In still going ahead with my project and hope it can do something for the interim till a new bird gets in orbit.

 

[Keith Brannen]

It seems that anything I want to watch on ku tends to have some issues. Equity, then RTN on AMC-9 now this.

Don't I know it! Besides those you list, twice now channels have moved to LNBs that are the farthest off centre on my dishes. For example, RTN when it went to AMC9 it was to a LNB that was at the time 10 degrees off-centre on a 60e (fine for the feeds which were always strong, but horrible for RTN)! It took a lot of re-arranging of dishes and LNBs to eventually correct that problem. One mux (with one FTE channel) moved from boresight on a 80cm dish to another LNB 10 degrees off-centre on a different 80cm (fortunately, in that case, their new signal is still fairly strong, but it was at maximum on the first satellite).

I'm glad I don't have issues with c band like this but having a monster reflector covers quite a bit of this type of stuff up.

Unfortunately for me, there are LOS and wife issues which seem to eliminate a c band dish in my future!

AMC-4 is ready for replacement from what I read in your link.

According to Lynsat, early next year (the sooner the better).

EDIT: And as per usual, HTN is down to 15 again (high of 45 earlier in the day).

 

[tvropro]

Unfortunately for me, there are LOS and wife issues which seem to eliminate a c band dish in my future!

Bummer

According to Lynsat, early next year (the sooner the better).

EDIT: And as per usual, HTN is down to 15 again (high of 45 earlier in the day).

It may be the bird cannot get enough power from the solar antenna's certain times of the day and the storage batteries are depleted. Mine was breaking up like crazy last night. It will probably be a week before my custom lnbf holder is built. I spoke with my neighbor yesterday and from what he told me it's going to be a work of art. He was talking about machining parts from blocks of aluminum. Can't wait to see the finished product.

 

[Keith Brannen]

It will probably be a week before my custom lnbf holder is built. I spoke with my neighbor yesterday and from what he told me it's going to be a work of art. He was talking about machining parts from blocks of aluminum. Can't wait to see the finished product.

Naturally, we expect updates and photos!

 

[pedrogarcia]

Interesting project, I started with a 90cm Patriot dish bored on 101 and 97 offset and then changed it to 101 offset and the difference was minimal measured on the spec analyzer.
My experience of wide eliptical dishes is that they have a wide or multi focal point to assist adjacent satellite capture over about 6/8 degrees provided the dish is tilted. If not tilted or greater LNB spread it just looses out on the more important dish surface area. LNB skew is still a slight issue since LNB manufacturing tolerances are not great.
Look forward to hearing your results

 

[pedrogarcia]

Pix of my LNBs including 97, 101, 107 Anik F1R

 

[tvropro]

Naturally, we expect updates and photos!

As things happen I will post. Rome wasn't built in a day

 

[tvropro]

Pix of my LNBs including 97, 101, 107 Anik F1R

Nice setup.

 

[tvropro]

First Update

I got an update from my neighbor. The cap section has been machined out of aluminum and has a flat front on it with a tab that will attach to the swivel bracket for skewing the 2 lnbf's. I now fully understand how he's doing it.

Like clockwork HTN kept on dropping in power yesterday evening till breakup. :rant::rant:

 

[guapoharry]

What about this?

Guess it doesn't skew, does it...? You could bend the rail instead, but that isn't very scientific....

 

[pedrogarcia]

What about this?

Guess it doesn't skew, does it...? You could bend the rail instead, but that isn't very scientific....

Sure it skews fine but slotted bar will just need bending slightly to the satellites arc. It is probably easier to have the bar thru 90 degrees as in my pix #27 further up the page. this is a standard accessory in Europe that costs about $6 with 3 LNB holders.

 

[tvropro]

Update

LNBF holder should be done by tomorrow (Saturday) can't wait to try it out

 

[Anole]

another old idea:

There was an idea that one of the members came up with a few years ago.
He managed to skew the entire dish.
It got brought up again recently in a thread where Linuxman and I discussed and dug up all the old documentation.
The original inventor used a low cost (around $8?) boat seat swivel for the purpose.

With that supplying the skew, an LNB holder would then be much simplified.

And if the ADTH is elliptical, all the more reason to skew the dish.

 

[tvropro]

There was an idea that one of the members came up with a few years ago.
He managed to skew the entire dish.
It got brought up again recently in a thread where Linuxman and I discussed and dug up all the old documentation.
The original inventor used a low cost (around $8?) boat seat swivel for the purpose.

With that supplying the skew, an LNB holder would then be much simplified.

And if the ADTH is elliptical, all the more reason to skew the dish.

I have been thinking about fabricating something to skew the dish next, by using two steel plates. I want to see how well the new holder works out first. There is only so much you can gain with a dual feed to start with. If skewing the entire dish would only add up to a few quality points would It be worth it? I don't know at this time. If HTN didn't crap out nightly I probably wouldn't even be doing this. But in a way it's fun to experiment and learn.

 

[Anole]

Well, truth is, with your nightly crap-out, I was wondering if we were beating a dead horse, here.
The correct solution may just be the usual answer: Get A Bigger Dish! -

 

[tvropro]

The correct solution may just be the usual answer: Get A Bigger Dish! -

Actually I think I can just beat breakup if I boresighted AMC-4 but 97 drops too much that way. I guess I want the best of both worlds.

Yes a bigger dish is the answer for all these kind of problems. When I can snag a 6 foot for taking it away I'll be there. Ain't enough that I watch on Ku to warrent putting $$$ into a new dish. Saving my pennies for a new receiver. Want all the Powervu and DC2 HD stuff when open on C band plus S2.

 

[Anole]

last resort:

The GeoSat Bullets are pretty good, but do you have any other LNB around ya might try for that fading signal?

Or go on the road and look for a spare freebie dish - break this problem into a two dish solution.

 

[tvropro]

Update

Well it's done but needs to go back to the machine shop. The cap needs to be redone since it was too small and the angle was off 10 degrees. I tore the whole original assembly off and let my machinest buddy get exact dimensions & angles. While I was at It I boresighted AMC-4 this afternoon and made G-19 the offset. Lets see how that works till revision bracket is done.

 

[tvropro]

Pictures of finished holder

Here are pictures of the finished LNBF holder. Now I have to find some time to put it on and see how it works. It's all aluminum and can skew and adjust up to satellites 8 degrees apart.