In a previous blog post I mentioned I was building a 9:1 unun for a long-wire antenna. I just complete the project and the results were a little less than I had hoped for. The SWR was a little high on several bands…in the 2.5-3.2 range. That’s a little too high for me to feel comfortable when using my QRP rigs.
The video will be out later this week with the test results shown. I want to solicit comments from other builders out there who may have suggestions on how to get better results.
Stay tuned.
Hope to meet you on the air soon.
73 de John/W5CYF
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I just finished one too John, I haven’t tried it out yet. I am hoping to be able to use it to get several bands using the internal tuner on my 450D.
Doug, Thanks for the comment. I tested mine today and it works on a rather narrow band range. However we had rain and I really did not get a good chance to adjust lengths of radiator and counterpoise. I think with some work it will be a good portable antenna. Video will be posted Friday with the test results. 73/John
there is a video on you tub that is very interesting it is show with a mfj 259 antenna analyzer showing SWR on 80 thru 10 meters with 1.1.1 or slightly higher very impress the length of wire is suppose to be 66 feet I was thinking about trying to built one myself. don’t recall a counter poise on it however Date: Wed, 1 Jun 2016 21:07:02 +0000 To: kf6gc@live.com
O.W.,
Thanks for sending along your comment. I think with some more tweaking the antenna will be OK for what I was intending to use it for. I just need to spend some more time on the wire lengths to get the SWR down to a range I am comfortable with. Let me know how yours works out. 73/John
Typically, the 9:1 unun is used with a non-resonant wire and relies on an ATU for impedance matching. I typically use a 30 foot wire, 18-ft of coax and no counterpoise. Most ATUs will match it on all bands from 40M on up with decent performance for a quick portable antenna.
Craig,
Great advice, I’ve used the radiator at ~30 feet with good results also. My next step is to use a shorter coax as you suggest. My antenna works good but think with some additional time spent on different lengths of coax/radiators it will be even better. 73/John