Analogue NTSC Polarity

[equant]

New setup: 10´ dish, with C/Ku going to a 920 4dtv receiver.

I´m not sure if I setup the polarity on the feedhorn 90 degrees out of alignment or not.

Ok, so here´s my question. Does polarity matter when you´re viewing a C Band analogue ntsc signal? Because it sure didn´t seem to matter. I was watching Disney (it was free at the time), TBN, Arts and a few other channels like them just fine. It didn´t matter if in the setup I selected that my polarity was normal, or 90 degrees off. I was unable to get any Ku.

When I went to ´add a satellite´ and adjusted the skew, it never had any affect on the image. I could see the polarity change in the feedhorn, so I know it was moving.

Doesn´t this seem odd?
Any idea what´s going on here?

Thanks,
Nathan
Tucson, AZ USA

 

[voomvoom]

If you want to receive ku, look in the Menu, go to Options, 6, 4, 2, item #2 LNB Type: should be "C-Band and Ku-Band LNB's", if you have LNB's. If you have LNBF's, it should be "C-Band and Ku-Band LNBF's". Don't know, but maybe this is the problem? Good Luck!

Al

 

[equant]

My issue isn´t ¨How to receive Ku¨ but in stead, ¨Does polarity matter with cband analogue ntsc signals?¨ The reason I´m asking is because (a) I have evidence that it doesn´t and (b) this doesn´t make sense to me. Sorry if I rambled on too much and that wasn´t clear.

 

[voomvoom]

Well then, I went back and re-read your OP and if you adjusted the skew and it never changed, meaning you always had the picture? Then it sounds to me like you are only getting one side of the polarity. That could mean a bad polarotor (servo motor) or maybe you've done what I did once. I had the polarotor in the wrong possition and it would only move about 90 degrees or less. I couldn't figure out why I got both polarities on one sat and the next sat I only got one side of the polarity. I tried turning the feedhorn/lnb assembly 90 degrees and got the other polarity, but not both. It took me a while to figure out what I had done. I'm still not sure how I did it, because I think they are only supposed to go one way, but I had it off somehow. When I straightened it out, it's worked fine ever since.
The feedhorn assembly is normally in a 10:30/4:30 possition above the dish. Hope this helps!

Al

 

[Lynskyn]

Yes, polarity matters. I suppose if the probe is half way between horizontal and vertical, you could get a signal on both but I doubt it would be clear on either one. What feedhorn do you have? If it's a bullseye (2 c-band LNBs and 1 Ku LNB) then the polarity setting would have no effect on C-band, only on Ku.