[TowerTalk] Christman Phasing help!
R. David Eagle
kb8nnu at yahoo.com
Sat Sep 6 17:51:09 EDT 2025
Hi Jim,
I am going to remeasure the antennas tomorrow if the weather improves around here. I somehow misplaced the numbers. But anyways....The 2 quarterwave vertical sections I built out of 14G THHN held up by two HD spiderbeam poles mounted on 4x4's. The antennas are spaced 1/4 wave aprat. The feedpoint is about 6ft off the ground so I could run 2 quarter wave elevated radials off each. Currently, the radials are running parallel between the 2 antennas. The antennas are mounted NE - SW along the edge of hardwood forest with no other metal near the antennas. I wound a small impedance transformer this spring to hopefully take me from mid 30's to something closer to 50 but that didn't help much either. I was considering going the route of putting together a small LC network....but then I would have to have a means of switching that as well from when I go Broadside to endfire......or maybe not.
DaveKB8NNU
On Saturday, September 6, 2025 at 11:05:02 AM EDT, Jim Lux <jim at luxfamily.com> wrote:
what did you expect to see?
What are the impedances you see at the two verticals,without the coax, and with the other antenna "open"
On Fri, 5 Sep 2025 23:55:52 +0000 (UTC), "R. David Eagle via TowerTalk" <towertalk at contesting.com> wrote:
Hello all,
Let me preface this by saying this - I am NOT a phasing expert by any means so I thought I would tackle a new antenna project this summer and maybe learn something....or lose more hair! So any ways...I decided to put up a pair of phased 1/4 wave verticals and phase them via the Christman method. Each antenna has 2 raised radials. I ran across an article by W4NFR where he did exactly what I am attempting, BUT I am getting different results....naturally. I tuned each vertical to 7.100 exactly trying to get the lowest possible reactance on each. I checked and double check the RG-213 71 degree delay line and the 84 degree feeds to the verticals. Now, here is the puzzling part - when I put everything together in my homebrew directional switch box, my resonant frequencies are considerably higher when I switch between Northeast, Broadside, and Southwest. The resonant frequencies are near 7.450-7.500 where R=39 with X=6.
So I must be missing something here.....Anyone else had success with this?
Any help would greatly be appreciated!
DaveKB8NNU
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