58W Intelsat 9

[equant]

Got 58W last night (hazah!) but I can only seem to get V transponders with the exception of one H transponder (NHK @ 4040(H)). Looking at TheList and Lyngsat I see that there are transponders with the same frequency and symbol-rate but different polarities. For example 3882(H)27690 and 3882(V)27690.

I've messed with the H skew (servo controlled) and I don't pull in anything (except when I rotate to near the V polarity, and then I see the V transponder.

Ok, so what am I missing? Do I need a special LNB? Is there something funky about this bird?

Thanks.

 

[pendragon]

Are you sure the servo rotates all the way to H? It seems that is the most likely cause. Are you getting good quality readings on the V transponders that have identical RFs and SRs as the H transponders you can't get? What size/model of dish and LNB?

Less likely, you may have a cross-polarization problem (H leaking into V and vice versa). Intelsat 9 as you noted makes such a problem more obvious than the norm. While some dishes and feeds are particularly vulnerable to this, cross-pol can also be caused by simple alignment errors.

 

[equant]

Are you sure the servo rotates all the way to H?

Pretty sure. I can get one H transponder on 58W, and I don't have any trouble with H on any other satellites across the arc.

Are you getting good quality readings on the V transponders that have identical RFs and SRs as the H transponders you can't get?

Yes. Not great, but good. No breakup in picture. 50-60% quality on a Visionsat for the V, 0% for H.

What size/model of dish and LNB?

10' Dish. Don't know the model of dish nor LNB.

Less likely, you may have a cross-polarization problem (H leaking into V and vice versa). Intelsat 9 as you noted makes such a problem more obvious than the norm. While some dishes and feeds are particularly vulnerable to this, cross-pol can also be caused by simple alignment errors.

Ugh, I don't even know where to start. Is it possible that the resolution of the polarity servo isn't fine enough?

 

[pendragon]

Pretty sure. I can get one H transponder on 58W, and I don't have any trouble with H on any other satellites across the arc.

If the servo is binding somehow or at its rotation limit, it may not move all the way necessary for a correct H orientation. That might be good enough for other sats, but 58W is a bit more demanding. 4040H is easier than some of the other H transponders. What make me suspect this kind of problem is you are able to get the V polarizations on this bird.

10' Dish. Don't know the model of dish nor LNB.

I get everything fine on my 10' and 6'.

Ugh, I don't even know where to start. Is it possible that the resolution of the polarity servo isn't fine enough?

I doubt the servo resolution is the problem. The angle needs to be reasonably far off for the signal to deteriorate to the extent you describe. Can you manually rotate the LNB to both polarization positions to verify it isn't some mechanical problem with the servo?

Are you centered on 58W, up/down and east/west? Any objects blocking the view? I don't know your receiver and how its SQ values compare, but on the surface the V numbers sound a bit low.

As to other problems that could lead to an increase in cross-polarization, the LNB might be off the focal point and/or not accurately centered. A missing or misadjusted scalar could also increase cross-polarization. Normally if everything is setup correctly and not defective, you shouldn't have significant issues.

 

[equant]

As to other problems that could lead to an increase in cross-polarization, the LNB might be off the focal point and/or not accurately centered. A missing or misadjusted scalar could also increase cross-polarization. Normally if everything is setup correctly and not defective, you shouldn't have significant issues.

I'll double check the skew first, but I think your last comment is most likely my problem. I've never spent any energy making sure any of the above things were setup right. Until now, I haven't needed to. I guess I'm just nervous about screwing everything up. "Most" TV is better than "No" TV.

Thanks for your help.