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Re: Helix feed details



Greg:

Here's what I did.  I think I understand the "bump" on the "panel" side of the N connector that you're talking about.

I first discovered the bump after I drilled a hole in the reflector large enough for the pin of the N, but realized that the screw holes 
wouldn't touch the reflector because the bump kept it from laying down flat.

I used a reamer to enlarge the hole such that the bump fit through the hole and the mounting screw holes laid flat on the reflector.

But yes, the 1/4 turn matching section was too far away from the reflector, so I used washers between the reflector and the N 
connector to pull the N connector back a bit.

Then a friend came over with an antenna analyzer that would do up to 3 GHz.  We experimented with the spacing, and found the 
greatest return loss (best match) with zero washers in place, and the matching section much farther from the reflector than the G3RUH-
spec distance.  So I left it there.

Here's what mine looks like, on a PrimeStar dish: 

http://www.draig.org/gallery/200106/20010612a-webpic-021.jpg
http://www.draig.org/gallery/200106/20010612a-webpic-022.jpg
http://www.draig.org/gallery/200106/20010612a-webpic-023.jpg

I ended up putting the washers behind the N connector, just to keep my 1/4 inch screws from protruding too far out of the reflector.

David, ky0dr


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