End Fed Wire - 40m high swr suggestions

Discussion in 'Ham Radio Discussions' started by KC2IEB, Sep 24, 2020.

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  1. K8BZ

    K8BZ Ham Member QRZ Page

    KA0HCP and others have given you some good advice. I won't repeat their advice but will just add a little info.

    Your rigs built in tuner has limitations. It won't match anything; only reasonably close mismatches. If you want to use a random wire on multiple bands you will need an external tuner.

    You should also know where the high voltage points are on any random wire antenna. You don't want those high voltage points to come into your shack if your external tuner is feeding the random wire directly. The end of any random wire antenna is the high voltage point. Any even 1/4 wavelength measuring back from the end will be another high voltage point; and every odd 1/4 wave back from the end will be a low voltage point. If you have these high voltage points near your radio gear you can expect to have RF in the shack that can cause erratic operation of electronic gear as well as possible RF burns to the operator. You will be frustrated trying to eliminate the RF in your shack with various chokes etc.

    If you insist on using an end fed wire then decide which bands you want to use the most and graph the high voltage points for each band on some graph paper beginning at the end of the antenna and working back toward your shack. Find a point on the graph that is the lowest voltage points on as many bands of most interest as possible, and cut your end fed wire to that length. Then use a good external tuner to tune the antenna.

    Random wires can be good antennas. I have used them for years in the past. But there are much better options available now, that aren't as persnickety as a random wire. Check out some of the options previously mentioned. And I will also mention the ZS6BKW. It's an excellent multi band antenna that has minimal need of a tuner and will keep the RF away from your gear.

    Good luck and keep learning. 73,
     
    KA4DPO, KC2IEB and WN1MB like this.
  2. KC3SWL

    KC3SWL XML Subscriber QRZ Page

    Everyone already stated the obvious,so I will state the not so obvious.
    Have lots of radials on that antenna.
    Use quality coax.
    Double check the connectors.
    Try different baluns.

    Use a quality antenna tuner. One that has both PL 259 ,plus wire terminal and balanced line connections. You will appreciate this later as the types of antennas you experiment with change in regards to feedline. My personal preference is a Dentron SuperTuner. It does all of that and is damn ear bulletproof.
    I have a negative bias towards MFJ. None of their brand new gear worked out for me, however it's cheap so buy at your own risk.

    You will need an external SWR meter to monitor that SWR. I don't rely on an internal meter especially the led bar graphs as they may be off by a bit. A nice Daiwa or other type of meter will come handy. I myself use a Drake W-4. Old but reliable.
    Good luck
    maybe I'll hear your call one day on the bands.
     
    KA4DPO and KC2IEB like this.
  3. AE1N

    AE1N Ham Member QRZ Page

    Without huge fanfare: Get a good tuner!
     
    K8BZ and KC2IEB like this.
  4. KC2IEB

    KC2IEB XML Subscriber QRZ Page

    Thanks all - as a summary, the usual troubleshooting is important:
    • Check the connectors
    • Check the feedline
    • Check the balun/unun
    I also appreciate the advice on the internal tuner - I'm shopping for a tuner, since I'm excited with the prospect of building antennas, but I won't have a lot of room to keep band-specific antennas up.

    I noticed a couple things - I was overdriving the original balun I had, so I upgraded that to something much more suited for FT8's duty cycle.

    I've noticed that the internal tuner has big trouble on 80m when I have a 1:1 balun attached near the transceiver, but can tune 40m no problem. When I pull out the 1:1 balun, I can tune 80, but not 40. :) So, this leads me to believe I'm adding or doing SOMETHING to the feedline. Really, I think I'm probably adding length. So, I'm going to build a slightly longer coax cable to see if that cleans things up. Otherwise, I'm happy with the progress I made today.

    I really appreciate the advice on looking at dipoles. I'm a little flummoxed on how I can get a dipole to fit, as I don't have a heck of a lot of side to side real estate, though I do have plenty of front to back real estate.

    Thanks again everyone!

    73, Chris
     
    K8BZ likes this.
  5. KN4CQB

    KN4CQB XML Subscriber QRZ Page

    This. Mine was not great when I first set it up. I then changed the length to 66" and it worked quite well.
     
  6. W9WQA

    W9WQA Ham Member QRZ Page

    no balun. just mess with length and get a tuner. i used an sg230,now a mfj998rt and tune 160 thru 6. (6 sometime)
    ?80 feet appx with one trap 16 feet up..auto tune so much ezer!!
     
    KA4DPO likes this.
  7. K0RGR

    K0RGR Premium Subscriber QRZ Page

    I have an EF wire with a 9:1 balun. One end of the wire is at about 50 feet and the other is about 10 feet. My wire is ~59 feet long, and the antenna works from 160-6 meters with a 3:1 SWR - my little autotuner can match it over that entire range. I do not use a counterpoise. Now, the antenna does not perform nearly as well as the multiband dipole in the same general space. But it makes operation easy on bands that I don't have a matched antenna for, like 60 and 160 meters.
     
    W4NNF likes this.
  8. KC2IEB

    KC2IEB XML Subscriber QRZ Page

    Thanks - I really appreciate hearing how other operators are using a combination of single-band and multiband antennas. I don't yet know what I enjoy the most, so the end fed wire is a decent compromise while I learn my radio, my yard, and the HF spectrum.
     
  9. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page


    KC3SWL said it,,,,,,,,,,,Have lots of radials. I can't stress the importance of a good RF ground (return path) enough for an end fed wire to work properly.

    Now then, 73 feet is not a terrible length but you may want to shorten it by about three feet to begin with and whatever you do, ditch the UnUn. Those transformers can introduce a lot of loss, also, the impedance has to be just right in order for them to work, chances of that are slim. Best solution is to use an antenna tuner that can tune end fed wires, almost all of them can.

    Personally, I prefer an L network tuner because it has the fewest components, and the least loss of any wire tuner. Do this, and you will have a functional end fed antenna. A more foolproof approach was pointed out by W4IOA, just feed it in the center with ladder line, and use the balanced input on a tuner. That will work, and you won't need radials.
     
    WN1MB likes this.
  10. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    Chris, all antenna tuners are impedance transformers. Like I said, I prefer an L-network tuner for end fed wires, but any decent tuner will work. Fixed transformers with ferrites can be made to work, but will always introduce loss, more loss than a variable tuner. As for the 1:1 choke, if you have a really good RF ground you should not need a choke, your tuner will transfer the maximum amount of current to the wire, and there should not be any RF in the shack.

    The most fool proof all band antenna would be to feed your 73 foot wire in the middle with ladder line. You can use 300 ohm window line, it is smaller and less obtrusive, and will handle a KW when matched.
    Because the system is balanced, you will not need any radials. You can run the balanced feed line to a 1:1 Balun close to your point of entry, and run a short length of coax to a tuner. You can use an auto tuner if you like, I prefer manual tuners for reasons I won't press here, but either one will work if it has a decent matching range.

    An end fed wire can be made to work as well as a flat top antenna, but not better, and end fed antennas require that RF ground I keep talking about. Have fun experimenting, and don't give up, antennas are a lot of fun to design and construct.
     
    N1OOQ and KC2IEB like this.

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