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True Ladder Line and Wire Antennas

Will I have to "TUNE" my feedline?

Posted by Brian Duerr WB2JIX on

What follows are excerpts from an email reply to a customer that purchased a 240', end to end, 160M Doublet with 150' of feedline.. He was reading a lot of "expert" comments on the web about how much trouble it is to tune 600 ohm feed and was a bit concerned about what he may be in for.

Reading about open wire line on the internet is certainly going to make your head spin and ask yourself “oh man; what have I done?" I'd rather you worried about the future of our economy with the Gov't shut down.

Most of the "experts" have never used open wire line or, they are so anal retentive that they have to "model" everything to death and then tell everyone else that there's won't work unless they follow exactly what they did.

Most people that use an open wire fed antenna, with the 600 ohm feed, not the 450 stuff, follow good, practical antenna installation techniques, use a quality tuner and balun WITH THE CORRECT RATIO (which thankfully, you have), and you're on the air.

Sometimes, you may want to shorten the end to end length a bit and/or change feed length a little.

Most times, if you keep the feedline away from anything that can cause an imbalance, keep each leg off the ground symmetrically, allow the feedline to swing free (don't tie it to things), AND, use good grounding tactics in the shack, you won't have to do anything. It's really just a few percent of installs that have any work to do at all.

For instance, I always bring one of my doublets to Field Day, both winter and summer. We find a tree to toss a line into for the apex to use as an inverted V. I find a spot to setup my tent and table, pull the feedline over to my tuner, cut it, connect to the tuner and I'm on the air with all bands for the day. It really can be that easy. In fact, if I didn't place the feedline spacers every two feet so I could count them to determine the length, I would never know what it was. I am usually not concerned with the length unless, it ends up at 66’ or so and causes problems on 20M.

I helped a guy over the last few weeks that had your exact, same setup (tuner and balun) only he wanted to use the Balun Designs 1171T tuner balun. In many cases, that’s the right combo. He had all kinds of problems trying to get all band operation. I disagreed and said I really think he'd be better off with the 4114T. We worked on this for three weeks and tried everything BUT a different balun.

So, I purchased one and sent it to him to try. Guess what? It worked and solved his problem. He was running high power with a new, solid state, auto tune amp as well.

Balun Designs is the best in the business but sometimes, things just don't work the way we think they should. We just have to be open to trying something different.

If you have to change feed lengths, it's not a big deal. I just read on QRZ of a guy that changed lengths multiple times and soldered each connection, every time. That's kind of stupid. Just twist the wires together, go inside and try it. If not, untwist, take a little more off and repeat. When you find a length that works ALL bands AND full power, now you solder. 

This is where an antenna analyzer can come in handy. When I had problems on my 160M version, not being able to tune the low end of 160, I used my MFJ-259 to determine that the SWR was above 25:1. My MFJ-998 couldn't go that high. So, I had to make changes to drop that within range, knowing it would solve my problem. I wasn't cutting and changing lengths blindly. I knew where things had to go. Of course, if I wasn't going to use 160, I would have stopped making changes anyway.

There's a photo on my site about how you tie a knot in the line, solder that area and tuck it inside a spacer and you're done.

Heck, for my 88' feed on my 160 doublet in Vermont, I never went back and soldered it. EVER! I left the wires twisted for about four years. There should be no stress on the feed or the antenna, to cause anything to pull apart.

I hope you can sleep after this email and have a laugh!

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