[PVRCNC] [PVRC] Feeling antenna challenged for SS?

[WILLIE BABER]

Hi Jim, and All,
 
Speaking of a antenna challenged SS, I will be on for SS but I am now racing against time to get a tower and tribander up, operating from Idaho.
 
At least I will be on with wires, hi....
 
73, Will, wj9b

--- On Sun, 10/23/11, Jim K4QPL <k4qpl at nc.rr.com> wrote:


From: Jim K4QPL <k4qpl at nc.rr.com>
Subject: [PVRC] Feeling antenna challenged for SS?
To: "PVRC" <pvrc at mailman.qth.net>, "PVRC-NC" <pvrcnc at mailman.qth.net>
Date: Sunday, October 23, 2011, 9:32 PM



I don't take any credit for it, but this weekend's antenna project has turned out so well I can't resist passing it on before SS. (It was also a great excuse to enjoy the Fall days without raking leaves!)

My goal was a second tribander, aimed NW, that I could use with my second radio. Not having the bread or motivation for a second tower I started looking around for something better than a dipole, like a wire something specifically for domestic contests. Had messed with the idea of a Moxon (like the pattern) but the wisdom of people who know a lot more about antennas than I do, (K2AV), was that a triband Moxon could be REAL tricky to get set up properly.

Did a google search and came up with this which is a QST reprint:

http://www.ve7ca.net/ART/VE7CA2elyagi.pdf

Reading the intro was like he was reading my mind--he just did it 10 years ago! But that's what's so cool. Almost same place in the sunspot cycle. The other thing that is important is that I have a lot of trees and it's impossible to find the right gaps to put up conventional wide-spaced wire yagis. If you've got an 8' wide path between two =>40' trees (strategically positioned to give you a W-NW aim) you can put up one of these babies.

I followed his dimensions EXACTLY.  Used my 75' tower for one end support and a nearby tree with a rope over a branch at about same level. Spud gun got it there on the second shot.

Getting exact horizontal balance at final height was a bit tricky, (the RG8X adds progressively more weight to the DE side as it goes up) but again, follow instructions by sliding the knots on the bridle and you'll hit it eventually.

Raised it to about 40'. Put the MFJ analyzer on it and was spot on for 3 bands. Even the hairpin match hit 48 Ohms on the first try which is close 'nuff to 52 for me!  Your mileage may vary. Doing it again I'd probably add a couple inches to the 20M dimensions to concentrate on the cw end, but SWR is about the same as my TH7, 1.6 at 14050; 1.2 at 14200. Similar on 15 and 10. For cw and phone it's perfect as is.

I also tried raising it to about 60' but that brought it closer to the top of my tower and nearer the TH7. SWR started looking funny. Maybe some interaction.

Connected it to the six-pak so I could do side by side comparisons with the TH7. More good news. Tuning through the bands receiving, it was not unexpected, but confirmed, that for the 5, 8, 9 and the near 7 and 0 call areas the low homebrew 2 el Yagi was about 1 S unit BETTER than the 75' 3 el tribander. They evened out on 6's but for DX, especially for the JA's on 10M this evening the TH7 pulled ahead again. Worked a 5 in TX and did comparisons. Transmitted signal reports followed Rx results. So, it's ideal for SS, NAQP, etc.

So, for about the same cost and space requirements as a dipole you can have a 2 element tribander aimed for where the high band SS QSO's will be this year. And if the XYL or neighbors are a consideration, take it down after the contest, roll it up and bring it out again next time. Also great for FD.

Anyone who wants to try it and has questions, reply off-reflector. Be glad to share some additional construction tips.

73,

Jim, K4QPL
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