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Build your own 9:1 unun antenna on the cheap!

Discussion in 'Amateur Radio News' started by W5KV, Aug 31, 2017.

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  1. W5KV

    W5KV XML Subscriber QRZ Page

    Building the popular 9:1 unun antenna based on the popular EARCHI antenna design. An antenna that works relatively well with an internal tuner for 40-6 meters.

    A popular antenna for portable ham radio operations or even multi - band operation at home. Assembled this one for less than $20, but it can probably be done cheaper if you have existing parts/container.

    Toroids can be found at hamfests, online retailers (Amazon, Palomar Engineers, eBay, etc), and many other sources. Plastic enclosures can be found online as well. Our local Frys carries the plastic/metal enclosure for electronics projects. Save yourself a few dollars and build one of these popular multiband antennas!


    KK5R, N5NSN, W7GST and 3 others like this.
  2. KD9AUY

    KD9AUY Ham Member QRZ Page

    I have done the same thing ,it was nice of them to post the bill of materials and assembly instructions, we did it as a club project many were made, and used on field day . If you lengthen the wire you can tune up a couple more bands. Good job 73 de KD9AUY Stan
    F4HVY, W7GST and W5KV like this.
  3. K4QM

    K4QM Ham Member QRZ Page

    Where is the B/M?

    Clayton N4EV
    KG7LSD likes this.
  4. N5EKF

    N5EKF XML Subscriber QRZ Page

    Just received a balun kit from The Wireman. I was expecting a completed one but I guess I should shop with my glasses on. I was trying to figure out how to build in a section of PVC pipe. Think I will go with the square enclosure like you did but use a different mount and eye bolts to attach dipole legs. Good video. It was most helpful!

    Cheers Mate,
    Elmer N5EKF
    N2LJN, W7GST, KD9AUY and 1 other person like this.
  5. KT5OT

    KT5OT XML Subscriber QRZ Page

    bruce beckett with maple leaf studios builds a 250 watt baun in 1 1/2 pvc pipe with caps on each end. mine has 117 ft. #14 wire and tunes 160-10 with internal tuner
    W7GST and KD9AUY like this.
  6. NJ1S

    NJ1S Ham Member QRZ Page

    Nice QRZ profile. I enjoyed reading your information. I think citizen band frequencies were very popular in the 70's, hihi. 73
    KD9AUY likes this.
  7. N1RAP

    N1RAP Ham Member QRZ Page

    It is the left red wire to the antenna terminal?? The right one you already shorted with left black ??
  8. W0CC

    W0CC Ham Member QRZ Page

    Several years ago, our club, KOANT, built similar units as a project. We used 29 feet of wire
    for a radiating element and no counterpoise, relying on the feed-line shield common mode.
    With this antenna, usually in "field day" conditions, we have worked all continents. I have
    over 100 QSO's using 2.5-5 watts on my FT-817. I have no difficulty tuning 6-40 meters
    with a Z-817. I am building a second UNUN with a 59 foot radiating element for the 80
    meter band. Surprising, it really works well and is ideal for QRP outdoor events.
    W7GST and KD9AUY like this.
  9. MW1CFN

    MW1CFN Ham Member QRZ Page

    I still keep an EARCHI wire in the car. Had extensive success with this type of antenna in the early days, but found it only works well as a vertical. It is considerably down on a 1/4 vertical, as one might expect given its convenient single wire design (which, in turn, is its 'strength') As a horizontal or sloper, and even with lots of ground gain, I found it quite poor. You can get a -30dB S/N report on WSPR to some distant shore, but whether that makes the antenna useful in practice is another question.

    Overall, whilst it's a fine multi-band solution at essentially zero cost, it's certainly a compromise antenna. That is very different from saying it is not worth trying.
    W9GOS, W5KV and KE0EYJ like this.
  10. W5KV

    W5KV XML Subscriber QRZ Page

    Thanks all. My next video will be on experimenting with a 'multi-ratio' balun from Palomar Engineers called the 'CUBE' a 2.25:1, 4:1 & 9:1 unun. Interested in showcasing the analyzer results by switching between the different ratios!

    Love building these little guys!
    K4DMZ and K3AN like this.

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