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Moxon ohms /SWR. 6 METERS.

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K4DXY, Sep 26, 2021.

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  1. K4DXY

    K4DXY Ham Member QRZ Page

    front.jpg Greetings, I just built a Moxon antenna for 6 meters with aluminum tubing. It was 2.2 SWR right at the start and after a little adjustment I got it down to 1.3:1 from 50 to 50. 200 And since that's where I operate In frequency I'm pretty happy with the SWR.

    Unfortunately My sinuses started getting the best of me so I had to quit messing with it for the day. Good SWR however when I checked it the next day I noticed It was about 43 ohms.
    I believe I know the answer but should I do more adjustment to get closer to 50 ohms or just be happy where it's at? Thanks, 73!
     
    Last edited: Sep 26, 2021
  2. WL7PM

    WL7PM Ham Member QRZ Page

    43 Ohms?
    I'd run it.
     
  3. K7MEM

    K7MEM Ham Member QRZ Page

    What is wrong with 1.3:1 or 43 Ohms? Getting the feed impedance to 50 Ohms may not change the SWR. Or the SWR may get worse.

    Just use it.

    If you continue to mess with it, there is a chance that you will just make it worse. Save your sinuses and leave it alone.
     
  4. WA4SIX

    WA4SIX Ham Member QRZ Page

    Have fun with your new antenna !!!

    Ed
     
  5. W9IQ

    W9IQ Ham Member QRZ Page

    I agree with the general sentiment that an SWR of 1.3 is probably not worth any further adjustment.

    But I do want to point out something about your "43 ohm" observation. When dealing with antennas, you should take note of not only the real resistance (R) but also the reactance (X). Ideally, this should be done right at the antenna feedpoint or with an analyzer that can be calibrated (OSL) to take the reading at the far end of the coax and then do the math to give you the R and X values at the feedpoint.

    If your feedpoint impedance was R=43 and X=0 then your SWR would be 1.16. So either there is a reactive, X, component or this reading was taken at the end of the coax without the benefit of an OSL calibration.

    Once you become comfortable working with both R and X, the fine tuning of an antenna becomes much easier understand.

    - Glenn W9IQ
     
  6. K4DXY

    K4DXY Ham Member QRZ Page

    Thanks for all the replies. Yeah I have built antennas for quite a few years but admit I don't really understand the R/X values as stated. I will certainly look into that and figure it out. I've always used analyzes but now using my NanoVNA. I agree of course that 43 ohms and 1.3 SWR is good enough, however I have discovered this antenna is very simple to adjust so I seriously doubt I'll make things worse by messing with it further. It has always been a curiosity factor with me, wanting to see how low I can get SWR On my diy antennas.

    Monday through friday looks like some nice cooler days for me so hopefully no rain will come my direction because I have a lot of stuff to do within that time period which includes moving the 6 M moxon to my mast with the rotator, doing some work on my 13B2 and a bit a preventative maintenance on my 10 meter antennas for winter. Again ... Thanks for all the advice and replies. 73!
     

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