Corotor II to LNBF Conversion?

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Lone Gunman

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Original poster
Mar 19, 2010
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Well, I've been sitting on a DMX 741S LNBF now for a couple of weeks that was bought to replace the Chaparral Corotor on my 10ft Winegard dish. Today I took the time to install that LNBF on that dish but before I did, I went to 4 different locations across the arc and checked S and Q on specific TPs in order to do an A/B test on that LNBF afterwards. What I found is that I either gained or stayed the same on ALL horizontal TPs but LOST between 5 and 15 points on Q on the Vertical TPs?? I did the initial setup on a Ku bird (AMC21) thinking that if I got that one right then everything else should be OK but that wasn't necessarily the case and I never did get AMC21 to give me the same Q on both H and V although the numbers I got were damn close too or better what I had before.

So being the "DIY" guy that I am, I started looking for reasons for this. I noticed that the antenna wires that stick out inside the feedhorn were not 90 degrees to each other so I tried to bend that vertical antenna wire ever so slightly to try to get the V signal quality a little better but it was a "no go".

So, it's still connected to my GI 920 right now and my AZBox Ultra is slaved to it but in the next day or two I'm planning to connect the AZ directly to that LNBF to see how it does. In the mean time, has anyone else had this problem and if so, did you find a fix for it?
 
Lone,

It might be interesting to rotate the lnbf 90deg. so that the horz probe becomes vert and vs vs. Then re run your test, see if the weak side stays the same or moves.
 
Lone,

It might be interesting to rotate the lnbf 90deg. so that the horz probe becomes vert and vs vs. Then re run your test, see if the weak side stays the same or moves.

Never thought of that one but I'll giv'er a try next time I mess with it.

Got to wondering if the vertical antenna wire inside the feedhorn is actually for vertical reception? And is the horizontal one for horizontal or does the vertical one receive horizontal and visa versa?
 
It's just the way you would think. When your dish is pointed at your South sat, the vert pin is straight up/down, the horz is left/right.
 
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