ESX242 C-band LNBF skew on motorized dish: 90 degrees off?

[ChrisW6ATV]

Hi all-

I bought an ESX242 dual-output C-band LNBF, and since my dish (10-foot KTI, I think) is motorized, I set the skew at 0 with the dish pointed at its apex/southernmost satellite (121 in my case). To me, zero meant "straight up" with the dish at the top of the arc.

I connected one output to my 4DTV DSR-922 receiver. Some notes say to set 4DTV receivers to "rotated 90 degrees" when using an LNBF, but I seemed not to have to do that. Next, I connected the other LNBF output to my X2 Premium receiver, and guess what? It is receiving signals (in a blind scan) with reversed polarity. (87 SES 2 3735 is received as "horizontal", for example.) OK, so the fix is simple: Go back and rotate the LNBF 90 degrees, and check the box for "rotated 90" on the DSR-922, and things will be fine on the X2.

My question is: Is all of this normal, and what I thought was "zero" skew is incorrect? (I did see one note that implied to point the 0-degree mark on an LNBF to the "3 o'clock" position on the dish, but it was not entirely clear to me.) Thanks.

[rrob311]

From what I remember the 4dtv is opposite of the x2. I had to tweak my settings that way to get everything to sync properly.

[ChrisW6ATV]

rrob311-

Thank you for the quick reply. I just moved the LNBF 90 degrees, and the "problem" is gone.

[el bandido]

You have discovered a common Manufacturing Defect.

Most of our lnbs are made on cheap assembly lines in China It appears that they stop the line only to change the brand name of the lnb without doing any other changes. I say this because several different brands of c band lnbs have the skew markings wrong, where 0 is really 3 o'clock.
Set the lnb skew to "3 o'clock" and everything should work correctly. Try to remember this if you buy any other c band lnb. Remember, not all of the c band lnbs have this defect but a lot of them do.

On another note, sometimes you can change lnbs and your current channel list in your receiver will become useless because not all lnbs receive the signal the same way. I found this out the hard way by spending about 1 hour trying to figure out why my new lnb would not work. This problem was solved by doing a fresh scan of each satellite. Some lnbs can be changed and the receiver will work without doing a thing, but if you put a new lnb on and get no signal from the satellite, try doing a blindscan before changing anything else! EB

[ChrisW6ATV]

Thanks, el bandido.

[Sublime]

Having 0 degrees at the 3 or 9 O'clock position makes perfect sense to me. When I set up the feedhorn/polarotor on my 10 foot dish years ago, I ended up with horizontal polarity at 0 degrees and vertical polarity at 90 degrees. (Actually, it ended up more like H=16deg, V=74deg, but close enough!) I guess it all depends on which polarity you prefer to call 0 degrees whether or not it makes sense to you or not. I know with a protractor in school, we always laid it flat on the desk with 0 being the horizontal line and 90 at the top.

[cpr43]

I also got one of this and have similar problems. All my previews skew setting where way to off on NSS806 compared t o the old model. So I decided to contact WSI, this is a c/p from their answer:

WSI International explaining the skew angle correction for your reference


Thanks for the email.

Yes, the polarization on this new unit is off by 45°. In addition, please make sure to slide in the dielectric plate perpendicular to the isolation bar.

Thanks,
WS International

[ChrisW6ATV]

Having 0 degrees at the 3 or 9 O'clock position makes perfect sense to me... I know with a protractor in school, we always laid it flat on the desk with 0 being the horizontal line and 90 at the top.

It took me a few minutes to think about this, but now it makes complete sense. My original comment "zero means straight up" was based on maps, with north (0 degrees) being "up", but maps refer to azimuth (horizontal/flat directions). Polarization refers to elevation ("vertical" directions, or lack of the same), and indeed zero degrees is horizontal in that context.

[77ta]

I've owned 2 c-band lnbf's, an esx241 and a ns741. Both sold by WSI and both with 0 skew set at 3 o'clock.

[ftanut]

I have jusr received my ESX242 LNBF and worked with it for about 1/2 hour. I scanned two satellites and the polarity are comming out wrong. The LNBF is connected to a ChannelMaster 4x4 switch, does swapping the coax cables from the LNBF to the 4x4 switch be the same as skewing the LNBF in the scalar ring.

It seems that somehow I have the LNBF skewed wrong.....So, is this LNBF zero have to be pointed to the 3 o'clock position for everything to be allright. Post # 7 of this thread mentioned that the LNBF is off by 45 degrees, if I place the zero at 3 o'clock then the LNBF zero is actually set at a 90 degrees angle.

Any less confusing explanation on the LNBF skew is greatly appreciated.

Thanks.