Sat Location problem

[Long Hair]

New ?

I was on galaxy28 watching and scanning on the ku side. I noticed that I need to move my dish east a few clicks to get the upper tps. But doing this makes the lower tps go bye bye. And on the C-band side I move the dish to get c, but lose ku. My ? is Can this be fixed by the declination angle or is there something else I should be looking at.
Thanks Long Hair.

 

[Lak7]

And on the C-band side I move the dish to get c, but lose ku.

It's not uncommon for Peak Ku and Peak C Band to be off a few clicks, but that's peak, you shouldn't loose one to get the other.
I'd guess that the LNBF is not pointing to the exact center of the Dish.

 

[Long Hair]

Some of the sats I point at, I can receive c/ku without moving the dish, and some I can't. What would you say the reason is on the ku side, moving the dish to get different transponders(Ku only). Maybe the LNB not being centered

 

[Lak7]

Some of the sats I point at, I can receive c/ku without moving the dish, and some I can't.

You need to map out what's going on.
Is everything tight on the Dish, Mount, Arm Connections, any wobble in the Dish.

 

[B.J.]

It's not uncommon for Peak Ku and Peak C Band to be off a few clicks, but that's peak, you shouldn't loose one to get the other.
I'd guess that the LNBF is not pointing to the exact center of the Dish.

I know that there are people here that strongly disagree with what I'm going to say here, but in my opinion, having the lnbf pointing to the exact center of the dish is not important at all. I've experimented by aiming my feedhorn probably a good 3 to 4' off center, and the signal didn't get worse.

What *IS* important, is to have the feedhorn at the exact focal point. If you have it at the focal point, the direction it's aiming has only minimal effect.

What I've observed is that if I have the wrong focal length, that it won't affect C-band that much, but the Ku pattern switches from a spot to sort of a donut shape, which has maximums, when off center. Sort of a situation where the side lobes are increased and the main center lobe goes away.

I have experienced the situation where Ku focuses at a different point from C-band, and generally you can fix that by adjusting the focal length. I'd recommend aiming at a sat using C-band, then try to adjust the focal length to maximize Ku band with that aim. After you get the focal length correct, you can most accurately locate sats using Ku, but if the focal length is off, they won't be the same.

Just my opinion. As I said, I know there are several knowledgeable people who don't agree, but I just wanted an alternative opinion out there.

 

[Sasquatch04]

Hiya BJ,,,,,mmmm,don t mean to intrude but the centering of the LNBF made a huge difference for my set up,,,,,,I used a laser pointer for setting up,,,,,

I guess in a way you are correct if it were only a C-Band lnb,,,,but for KU,,the signal is defenitely more finicky and therefore the centering is very important,,,,,

Cheers,,,

 

[Long Hair]

I'd recommend aiming at a sat using C-band, then try to adjust the focal length to maximize Ku band with that aim. After you get the focal length correct, you can most accurately locate sats using Ku, but if the focal length is off, they won't be the same.

For My focal length I have my support arm as far back on the scaler ring as possible, so unless I drill some new holes it's as good as it can be. I have measured the focal length many times and I'm good with that. The only thing I could adjust easy would be the F/D ratio. The lnb Support arms are not in the best shape, meaning they are bent so keeping the Lnb centered is fun. Thanks for the info. I'll fart around with the dish and see what magic I can make happen.

 

[Long Hair]

I looked up Joplin,Mo , your location - 37.1, -94.5
Check that the Mount is Plumb
Set your Main Axis angle - 37.75
Set your Declination - 5.56 (37.75 + 5.56 = 43.31) (46.69 on back of Dish) (43.31-90 = 46.69)
.

Checked my dish today reset true south, the Main Axis angle and the Declination.
But On the back of the dish I had to set it to 43.31, because 46.69 was way to high. Maybe I'm missing something but why subtract 43.31 from 90.Still I tried it but had to go back to 43.31 for Total Declination Angle. I have not checked to see if all my c and ku are working,maybe tommorow. But I did notice on w5 quality on H polarity was about 30% higher on avg. than V polarity. I've had this problem before I think my elevation needs to be fine tuned.

 

[Lak7]

Maybe I'm missing something but why subtract 43.31 from 90.

I guess it depends on your Angle Finder.
When I flip my angle finder from the Main Axis to the back of the Dish, the Horizon becomes Zero vs. the Sky.
If your main Axis is correct, try setting your Declination to peak signal, and adjust from there.

But I did notice on w5 quality on H polarity was about 30% higher on avg. than V polarity.

Put the Dish at your True South Sat, pop the cap off the DMX741, go behing the Dish and look up into the Feed, you should see a 1/4" metal Rod, that should e perfectly Horizontal.

 

[Long Hair]

Put the Dish at your True South Sat, pop the cap off the DMX741, go behind the Dish and look up into the Feed, you should see a 1/4" metal Rod, that should e perfectly Horizontal.

Checked that today and it's perfectly Horizontal, so no problem with the skew. I messed with the declination today and now on my true south 95west I can get c/ku upper and lower tps. And I checked w5 to see if that fixed the h vs v polarity problem, now it's the other way around V Polarity is higher and h is about 30% lower. Channel's I checked were the HBO's. So maybe after work tomorrow I will play with the declination some more and the elevation.

 

[Long Hair]

focal distance double check

So I thought I would play with the dish today, and I moved my zenith again this time I believe it's perfect(for now). Than I looked at the focal distance and with the tape measure it read's 35. But I think it needs to be at 36, so could someone double check my work for me. F=(D*D)/(16*d) D=(90*90)/d=(16*14)=36.10714 or 36inch. If this is right what should I do to fix my focal distance I'm max out on my distance as of now which is 35. Thanks

 

[Lak7]

Are you using the stock poles?
If so, I would then think your focal point would be in the range that the poles allow.
Remember that you need to measure 1/8" or 1/4" into the Feedhorn.
I would set the proper f/d ratio setting, then set Focal Point to best Ku signal.

 

[Long Hair]

Are you using the stock poles?
If so, I would then think your focal point would be in the range that the poles allow.
Remember that you need to measure 1/8" or 1/4" into the Feedhorn.
I would set the proper f/d ratio setting, then set Focal Point to best Ku signal.

Far as I know these are the stock poles,and I was thinking the same thing about them being in range.But measuring 1/4 into the feed gives me 35? So I'm going to drill new holes for the poles about 1" closer to the center of the dish. If that don't work, I can move them back. My dish is 7.5ft or 90inches and the depth is 14inches, so unless I'm missing something in the math the poles or short an inch.

 

[Lak7]

What do you have the f/d ratio set to?

 

[Long Hair]

What do you have the f/d ratio set to?

It came up to .40 so on the side of the lnbf I have it on 2. I when off the chart at the bottom of this link Tune Up Of Your Satellite.
If I'm right about it being an inch off,that would mean I'm seeing more than the dish, right? If so that would explain why, when I peak out a sat using my sf95c+ signal meter. I have to move back a little from the highest reading, I assume because it's picking up ground noise?

 

[Lak7]

It came up to .40 so on the side of the lnbf I have it on 2.

My Unimesh has the same f/d, I think all Unimesh are .40
"2" I thought was for .42, I have mine set at "0", that has it about 1/4" in front of the Scalar Ring.

my sf95c+ signal meter.

Those meters will indicate almost any signal, and have lead me astray many times.
Until I got a digital meter, I always used a Sat receiver and TV.

 

[Long Hair]

My Unimesh has the same f/d, I think all Unimesh are .40
"2" I thought was for .42, I have mine set at "0", that has it about 1/4" in front of the Scalar Ring.

Those meters will indicate almost any signal, and have lead me astray many times.
Until I got a digital meter, I always used a Sat receiver and TV.

Thanks for the info, I'll move it to 0 and see what that does. IF it does make it better I'll leave it their.And If it's still not perfect I have my drill charged.:up

 

[Long Hair]

A side note I moved the lnb arms in so I could put two screws on all four sides. What ever happened when I moved the arms 1 signal on 95west (3744 V 2206) was reading about 50% Quality and I thought that was good, but after adding the Four extra screws It now reads 92% Quality.But Now the Ku is off a few clicks again. So hopefully moving the f/d to 0 will fix that part.

 

[Long Hair]

Today I drilled new hole's for the lnb arms, so now I'm looking at about 36in. to the center. I moved the lnb f/d to 0,that put it 1/2in. from the scaler ring.So I moved it until I had it about 1/4 from the scaler ring, I get my 36 feed distance when I have it set 1/4 but the quality goes down on both c and ku. I also checked my skew again and it makes no real differences if I move or rotate it left or right on W5 151 Hbo. So I think my problem has something to do with transponder 18-24 on most sats in the arch. The only one that works good with the higher transponders is 95west my true south.

 

[Long Hair]

My Conclusion on this matter is the dish is warped or twisted.I have a different one to play with now

Thanks to all for your help.