Jonathan demonstrates using a K7QO noise bridge and shares a 3D printed OM0ET loop mount

Many thanks to Jonathan (KN6LFB) who shares the following in reply to my recent post about tuning mag loop antennas:

Hi Thomas,

I made a short video showing the use of a K7QO noise bridge from QRPguys to tune a mag loop antenna:

Also, inspired by your post, I dragged my OM0ET magloop up a mountain today for a POTA activation. I used a 3D printed tripod adapter of my own design that allows me to mount it on the collapsing legs from the Buddistick Pro. It makes the whole package a lot more manageable and light weight than carrying a camera tripod.

I had a successful activation of K-4454 on 20 meters, and thought you might enjoy some photos of the setup:

I’ve uploaded the design to Thingiverse at this address:

Jonathan KN6LFB

Wow! Thank you Jonathan. That short demonstration prompted me to order the K7QO noise bridge kit from QRPguys this morning. In fact, I plan to build this and keep it with my loop antenna as it’ll pair so nicely with my IC-705 and TX-500!

Thank you, also, for sharing those 3D files! I love that field setup at K-4454!

6 thoughts on “Jonathan demonstrates using a K7QO noise bridge and shares a 3D printed OM0ET loop mount”

  1. What a clever and useful idea! I’ve been thinking about buying (or building) a mag loop antenna, but put off by the hassle of tuning the little devil. This changed my mind. Thanks. 73 Skip K4EAK

  2. How well do mag loop antennas perform on HF, please, especially with QRP/low power ops?
    When they first popped up a few years ago, many down-played them because of (perceived) poor performance. Now, I see the big guns, like Thomas, buying into mag loops for portable ops.
    What am I missing?
    Dave, N8LBF

    1. Ha ha! “Small potato” might be a better description of me than “big gun.” 🙂

      Mag loops have been around for a very long time. They’ve simply become more popular in recent years due to the rise of QRM (man-made radio interference). I’m sure they’re also popular these days because they’re portable and low-profile (for those living in antenna-restricted areas).

      When tuned, loop antennas can be extremely effective. Especially on higher bands (think 20M and above). They’re workable on lower bands as well, but not as efficient.

      As you might have gathered, I don’t personally use loop antennas much because I can so easily deploy a simple wire antenna pretty much anywhere I go. But one park in particular that I enjoy activating has had a lot of QRM lately emanating from their visitor’s center. I think my loop antenna will come in very handy next time I activate that spot!


  3. I don’t own a Mag Loop. I want one now… Great video on tuning using a bridge!

    I appreciate a forum where Field Operators can share their ideas.

    de W7UDT

  4. Jonathan, Perfect timing. I was interested in purchasing the noise bridge to be used with my Mag Loop Antenna. Your demonstration displayed how easy it is to tune the loop without having to transmit power.

    I also read the noise bridge kit building instructions and it appears fairly easy enough, even for me 🙂 I will have to obtain one and report back.


  5. Thanks Guys.

    I am seriously thinking of getting a Mag Loop as it may be the only HF option I have for inside the condo. Plus, it will do double duty in the field. All of my EFHW and Hamstick attempts have been less than spectacular indoors.

    I would love to get the AlexLoop but the OM0ET will fit my budget better so I am being realistic and looking at it too.

    Alex has a small device that clamps over the coax connector called the AlexTune that helps tune a mag loop. It is essentially an RF field strength meter and you transmit a signal then tune for the LED’s brightest setting. The logic is when the SWR is the lowest the RF field will be the highest so the light will be the brightest (try saying that fast 3 times). There are several little ways to tune mag loops so just pick one that works best for you.

    Full Disclosure: I don’t have a mag loop but I have done extensive research over the last few days and this tip is a result of that research.

    Research means watching every Youtube video on mag loops and reading lots of reviews and discussions. Try reading eHam reviews without getting sleepy…


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