Hustler 5btv Radials

Discussion in 'Ham Radio Discussions' started by K6BFL, Jun 12, 2019.

ad: L-HROutlet
ad: l-rl
ad: Left-2
ad: MessiPaoloni-1
ad: Left-3
ad: Subscribe
ad: L-MFJ
ad: K5AB-Elect-1
  1. W5LZ

    W5LZ Ham Member QRZ Page

    I wonder what the reactance was on 40M when you were using that analyzer. That's what will tell you how well the thing will radiate, not SWR.
     
    KA4DPO likes this.
  2. W4NNF

    W4NNF XML Subscriber QRZ Page

    This is to some extent dependent on your lot. You may not be able, for example, to put down 1/4-wave radials. And as WF4W says, the number seems more important than the length. What did I do when I installed my 6BTV (recently)? I put down 25' foot radials. When it started getting hot, I stopped with 16, but I definitely intend to double that number when it cools off a bit. Nevertheless, the antenna works fine, getting me into eastern Europe, Russia, and the Mideast on 80. Oh, and do yourself a favor and get DX Engineering's nice radial plate... It makes installing radials a lot more pleasant. ;)

    I'm very happy with my ground-mounted Hustler (I also bought the DX Engineering tilt-over base, which I also recommend--if you live in an area that is likely to get higher than 45mph winds. It also makes putting the antenna up a one-man job). :)
     
    W4IOA and KA4DPO like this.
  3. K6BFL

    K6BFL Ham Member QRZ Page

    So you change the number of radials with the heat change? I will have to try that. Thanks for telling me. 73
     
  4. K6BFL

    K6BFL Ham Member QRZ Page

    I will have to check that.
     
  5. K6BFL

    K6BFL Ham Member QRZ Page

    it was just in 1 area so I will have to keep them on. I will try it out for fieldday and that should be a good test
     
  6. W4NNF

    W4NNF XML Subscriber QRZ Page

    Uh...no... LOL
     
  7. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    The thing with radials is that more is always better, up to a point. One hundred and twenty ground radials is considered to be a 90% efficient counterpoise. You can achieve 90% efficiency with three resonant quarter wave radials on an elevated vertical.

    Don't confuse SWR with efficiency. The purpose for radials is to provide a low impedance ground path, remember that a vertical antenna is only half of the circuit, ground comprises the other half. The lower the ground impedance is, the more RF current will flow in the radiating element. Current is what creates a radiation field around the antenna so the more current flowing in the vertical, the stronger the radiation field will be. You can have a 2:1 SWR and still have an efficient radiator.

    One thing that might help would be to do some field strength measurements, but it sounds like you are on the right track. Recheck the tuning for 40 meters. Check the SWR at several different points in the band, it should be lowest where you have it tuned, and rise on either side.
     
  8. K3GM

    K3GM Ham Member QRZ Page

    Typical impedance for a 1/4 wave vertical is in the neighborhood of 35-37 ohms over a perfect ground. That will yield a VSWR around 1.4:1. A shortened vertical like the BTV will have a feedpoint impedance even lower. When the BTV is mounted on the ground without radials, the ground losses will give a feedpoint impedance of around 50 ohms. So while your antenna looks flat and broad banded, it's unfortunately very inefficient. A BTV over a dense radial field is surprisingly narrow banded, and may be difficult to tune without a) playing with the traps, b) adding a uH or so of inductance at the base of the antenna to ground, c) add a 1.5:1 UNUN transformer at the feedpoint. Basically, if you've got a 1:1 VSWR using a 1/4 wave, directly fed vertical radiator, you have an inefficient antenna.
    The Hustler antennas were designed and marketed towards new users, or those who didn't want to deal with lots of radials. So it should be no surprise if you pound a pipe in the ground mount the BTV to it, that it will be broad and a indicate perfect match with a 50 ohm feedpoint impedance. Adding radials, lots of radials opens a can of worms with this antenna. Newtronics engineers didn't consider this possibility and never had provisions in the instructions. The antenna looks way to long and there's an urge to start cutting the tubing. This would be the worse thing to do. The answer is to adjust the traps; something the Newtronics instructions specifically tell you not to do. DX Engineering began adding tech notes when users installed big radial fields and encountered problems with tuning their BTV's. If you go this route, I urge you to read these tech notes. It's the only place you'll find them. Hustler sells way more antennas to those who are happy to install it on a steel post than those of us who want to lay down lots of radials, so they really can't be bothered. Properly tuned over a big radial field will yield excellent results with this antenna. It's just that it can be painful getting there!
     
    Last edited: Jun 14, 2019
    KA4DPO likes this.
  9. WF4W

    WF4W Premium Subscriber QRZ Page

    unfortunately, this is how verticals get a bad rap - they're installed without radials and perform equally bad in all directions :)

    That was what my elmers back in the 90's always told me and i believed it until I installed one myself and had the exact opposite experience. As you said, a properly installed BTV yields excellent results - my DXCC achievements speak to that...

    here is a link to the technical install document from DXEngineering - https://static.dxengineering.com/global/images/instructions/DXE-BTV-INSTALL-GUIDE-Rev0d.pdf
     
  10. KR2C

    KR2C Premium Subscriber QRZ Page

    I've used a 6BTV for field day. Mine was ground mounted bolted to a pipe driven into the ground. From the 3 small bolts on the underside of of the base section (gnd) I put a short length of wire with an ring connector to the bolt. On the other end . I stripped off enough wire to hook 5 ground radials to. I had a total of 15 radials. On the far end of the radials, I made a loop in the wire. I used this to put a lawn staple through. This made laying out and spreading the radial evenly a breeze.

    While not optimal far a permanent installation, it worked very well for a field day deployment.
     
    WF4W likes this.

Share This Page