SWR Problem?

Discussion in 'General Technical Questions and Answers' started by N1QWI, Oct 21, 2020.

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  1. AI3V

    AI3V Ham Member QRZ Page

    It does get tedious listening to problems with "end fedz", and how "I have low swrs so it must be ok"

  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I don't know how I filled three ARRL logbooks (1000 QSOs per book) as a Novice in 1965 without having the faintest idea what my antenna SWR was.

    I did have an RF ammeter (WW2 surplus) and tuned my transmitter for maximum line current. Seemed to work.:p

    More instrumentation doesn't necessarily = a better signal.:)
    SM0GLD likes this.
  3. K8JD

    K8JD Ham Member QRZ Page

    Adding a ground partway along the coax is probably your error.
    That kind of antenna relies on the coax for the other half of the system.
    Factory made End fed antennas are nororiously picky about how they are installed, partly due to the fixed ratio Balun transformer used.
    If you had a wide range tuner at the antenna end of your coax , insead of a fixed ratio device, It would be a better all band antenna.
  4. K8JD

    K8JD Ham Member QRZ Page

    Since he's Verticle now he needs a different Balum ! (Passed along from a friend)
  5. KA0GKT

    KA0GKT Ham Member QRZ Page

    I remember a newbie Amateur around forty-odd years ago who complained about how poor band conditions were, he called CQ and couldn't ever get anyone to answer. He phoned and we talked.

    Now, this was during the peak of a pretty decent sunspot cycle and I was working the world. I told the newbie that the bands were hopping and all that I needed to do was give my call and say "Nebraska!" and I'd get jumped upon. I filled a couple of Uncle Leo's WRL log books and sent out a bunch of QSLs.

    I told him that I didn't have any problems, and he asked what the SWR on my antenna was. I answered that I had an end-fed wire and a home-brew tuner and was using the water pipes for a ground, but I'd guess that, considering the length, it was probably 20:1 on forty and anywhere from 1.5:1 to 50:1 on other bands. He said that his SWR was 1:1 on all bands, he didn't need a tuner and that there must be something wrong with my antenna. My answer was to say that something must be right with my antenna since I was making contacts. Then I asked, "What kind of antenna do you have?"

    He said, "I don't have as much room as you have for antennas, I'm using an indoor antenna from Heathkit". I asked "Did you build it yourself? have you checked that it was constructed properly?" He said he bought it from the XYL of a silent key in a nearby big city and she said that her late husband used it all the time." Well, I needed to mow the lawn and weed the garden so I had to hang up.

    As the Cast Iron Kohler engine on the Monkey-Wards (by Toro) lawn tractor droned in my ears, I thought about my conversation with the newbie and cut the grass on the 2.7 Acres I mowed to keep the landlord happy. Something about it didn't ring true, so when my XYL waived me in for dinner, I pulled out my Heathkit catalogues to try and figure out what antenna he had, and then it came to me. I picked up the instrument connected to the twisted pair and gave him a ring.

    "Hey newbie, any luck"? I had my HF rig running in the background and fifteen was busy. He said, "Yep lots of luck...all bad. What's that I hear in the background?" I answered, "It's fifteen meters"... he said, You're $#!..ing me!" I said, "Nope. Could your indoor antenna be called a 'Cantenna'?" He answered in the affirmative and I explained what the "Cantenna" was and why he wasn't getting any contacts. He said, "But my SWR is perfect". More explanations were given and I invited him out to "The Farm" for a practical demonstration. A couple of weeks later, he had a nice new coaxial cable fed HyGain trap dipole and was having the time of his life shooting DX.

    The moral of the story is that SWR isn't as important as some folks make it out to be, and that an oil-soaked 50-Ohm resistor will provide a low SWR, but doesn't radiate worth a darn, and receives poorly to boot.

    One other moral, Any antenna is better than NO antenna, and by definition the "Cantenna" is NO antenna, but the SWR is low.
    WA9UAA, WG7X and KB3UWC like this.
  6. WA9SVD

    WA9SVD Ham Member QRZ Page

    Except, even a "Cantenna" can radiate a bit...:(:rolleyes:
  7. VK4XJB

    VK4XJB Ham Member QRZ Page

    When I have had a little too much time on my hands I have done 30m wspr with an air cooled dummy 25 feet up a tree. Also done it with a salt water dummy load made in a vegemite bottle sitting on the chook shed roof. With the salt water dummy I was being heard out to 2,400km. The resistive dummy only 1,500km.
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    But did you ever achieve an SWR less than 1:1? I've seen this mentioned several times here and think it's wonderful.:)

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