I just installed an MFJ 1796 on the roof. I had it tuned on the ground (per MFJ instructions) and expected a shift in SWR (again per instructions) when roof mounted. However, the SWR shifted completely out of sight. I also installed #4 ground wire from tripod to ground and ran it with and sometimes even zip-tied it to, the RG - coax. Could this be the problem. I don't want to do a massive retune if it's just a matter of relocating one or the other. I'm 99.9% sure nothing on the 1796 changed.

On 5/19/2016 11:44 AM, wrote:
I just installed an MFJ 1796 on the roof. I had it tuned on the ground
(per MFJ instructions) and expected a shift in SWR (again per instructions)
when roof mounted. However, the SWR shifted completely out of sight.
I also installed #4 ground wire from tripod to ground and ran it with
and sometimes even zip-tied it to, the RG - coax. Could this be the problem.
I don't want to do a massive retune if it's just a matter of relocating
one or
the other. I'm 99.9% sure nothing on the 1796 changed.

It seems like the nearby presence of the grounded wire would/should not
affect SWR viewed through the coax, unless there is something wrong
along the coax. A break in the shield? A bad connection at either end?
(Either of which could send the SWR out of sight even without the
ground wire. Maybe something went wrong along the coax as it was being
flexed around to the new location.)
Bob Wilson, WA9D