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Butternut HF6V questions

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KE0DMC, Oct 4, 2017.

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  1. KE0DMC

    KE0DMC Subscriber QRZ Page

    I just bought a Butternut HF6V antenna at a Hamfest.

    My question is does the coil at the base have a critical purpose? Can it be removed? I wasted it matches 30 meters that doesn't interest me.

    Secondly, can I hook a 50 ohm coax directly to it and forgo the 75 ohm matching coax?
     
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    The coil does help provide a better match. Is it missing? You can easily wind one yourself for about $2 in materials (or maybe zero if you have the wire). It performs another function as well: It puts the antenna at DC ground, which helps drain off static charges that cause receiver noise.

    The 1/4-wavelength section of 75 Ohm coax makes the HF6V a much better match on 20 meters; I'd use it. Again, if it's missing you can make one for a few dollars worth of coax, a PL-259 and a PL-258...total cost maybe $10-12.

    If the antenna was "used" (as in, installed outdoors previously) I'd take it all apart, use Scotchbright pads on all aluminum interconnections, and reassemble with NoAlox at all those points to keep it working for years. Carefully inspect the doorknob capacitors for cracks or faults -- if they fail, so does the antenna.

    HF6V with a good radial system is a very fine antenna.
     
    NH7RO likes this.
  3. N4UFO

    N4UFO Ham Member QRZ Page

    Congrats... the HF6V is a good antenna.
    but-hf6v.jpg

    If you mean the small coil made of 12-14 wire that goes between the feedpoint and the ground at the very bottom of the antenna, that is to match the feedpoint of the 80/75m section to 50 ohms. (commonly called the 'Q coil' as it was always part 'Q' in the assembly manual) - If you mean a large coil made of tubing mounted on 'stand offs' to one side of the main tubing, that would be a 160m add-on.

    The 75 ohm coax matches the 20m section from ~100 ohm down to 50 ohms... if you want to work 20m you need it.

    The 30m coil is the one that mounts coming off the upper tubing, but the bottom of it attaches to the middle of the 40m coil. I don't know if you can remove it or not, it might throw off the tuning of other bands.

    I would highly suggest that you download a copy of the HF6V manual and read it through thoroughly as you are going to need those instructions to proprly tune the antenna at your location. - I also recommend GUYING the antenna with rope. And of course, lots of radials.

    73, Kevin N4UFO
     
  4. NH7RO

    NH7RO Ham Member QRZ Page

    I removed my 30M coil as well as the 15M stub when I last used mine---I wanted to use it for 40M and the change seemed to be OK as far as I could tell. I didn't obsess over tuning it critically but just enough to get a reasonable match. I had 24 17' radials just under the surface of my lawn and might have put down more if we hadn't moved. I rebuilt the Q coil out of some 14 gauge THHN as the original got pretty banged up over the years.

    73,

    Jeff
     
  5. KE0DMC

    KE0DMC Subscriber QRZ Page

    So the Q coil stays and the 75 ohm coax goes. I have a 20 meter dipole.for 20 and am more interested in 40, 80, and 75 why I bought it.
    The Q coil windings are spread out at one end and bunched at the other. Should I equally space the windings?
    I checked the capacitors and they are in good shape.
     
  6. KE0DMC

    KE0DMC Subscriber QRZ Page

     
  7. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Well you didn't answer that in the normal way, but I read it all (above) anyway.

    200 s.f. of fencing isn't a sufficient radial system for 40m or 80m. Normally you'd want 20-30 radials all about 50' long, which is more like 2000 s.f. of surface area radials. The 5' deep pipe doesn't do anything.

    However, "everything works," it's all a matter of degree.

    The coil at the base is normally close wound and the windings have the same spacing from one end to the other.

    Ox-Guard will likely work fine: I use NoAlox, but I think they're similar.

    $100 or less is a good price, assuming everything is there.

    The HF6V actually used to cost about $99 brand new when it was first introduced. I had two of them with adjustable phasing via coax phase shift networks and relays so I could steer it, and it was a pretty good system on 40m. Allowed me to work DXCC+ (I think it was 112) in one weekend on 40m CW in the 1994 ARRL DX contest. I had only 36 radials (!) -- not enough -- under both of them. More would have been better.
     
  8. N4UFO

    N4UFO Ham Member QRZ Page

    It sounds like what you really wanted was an HF2V... which is 5' taller than the HF6V with less 'extras'. I suggest you download both the HF6V and HF2V manuals and study them both to understand the differences. Then consider adding four 12-17' long top loading wires as suggested in the HF2V manual, so that you can use less loading coil. (top loading is MUCH more efficient than base coil loading) Then I suggest 32 radials using Petsafe pet fencing wire... it's insulated solid 20 gauge copper (500' rolls can be found online for <$20)... meant to be in/on the ground. Then instead of springing for a ground plate and all that, 8 of the stripped 20 gauge wires will fit into one 10-12 gauge yellow terminal ring. That means for 32 radials, takes just 4 rings, which you can attach to the base of the HF6V.

    I similarly converted the used HF6V that I picked up into an 80/160m vertical by flipping & adding to the coils, doubling the bypass capacitance (160m requires double that for 80m) as well as adding some longer top loading wires. My radials are around 50 feet as suggested and I did the whole take apart and clean using Brasso and Scotchbrite pads and then coating with antioxidant. With 100 watts, I've been working 80m & 160m contacts all over the world.

    [​IMG]

    They say a picture is worth a thousand words... there you can see the Q coil, the radials, feedpoint, etc. (That's a tree ring, by the way... $10 at garden center)

    GL & happy low band DXing! 73, Kevin N4UFO
     
    AI3V, NH7RO and KI4LXB like this.
  9. W9GB

    W9GB Ham Member QRZ Page

    Butternut HF-6V HF 6-band Antenna (now owned and mfg. by DX Engineering).
    A current production version of this HF vertical antenna sells for $522.95 (w/o radials).
    https://www.dxengineering.com/parts/but-hf6v
    A current production version of the HF-2V antenna sells for $374.95 (w/o radials).
    https://www.dxengineering.com/parts/but-hf2v

    Butternut HF-6V (6-band HF operation)
    DX Engineering part number: BUT-HF6V
    Updated Instructions, Charts, Guides and Technical Information (2016, PDF)
    https://static.dxengineering.com/global/images/instructions/but-hf6v.pdf
    PAGE 15 : Installation of Matching Section (part R) and Q-Coil.

    Q-Coil (antenna’s base, feed-point)
    1.25 inch I.D., 17-turn coil wound with solid 12 AWG enameled copper wire.
    Length of coil will be dependent on the installation, stretch or shrink of the coil when following the tuning directions in the manual.

    75-ohm Matching Section (part R in latest 2016 manual)
    REQUIRED for Impedance matching 20-meter operation (~100 ohm [antenna] to ~50 ohm [coax] )
    The Electrical Length of this 75-ohm coaxial section is 1/4-wavelength at 20 meters.
    http://whites.sdsmt.edu/classes/ee481/notes/481Lecture9.pdf

    EDUCATIONAL VIDEO : Quarter-wavelength Matching Sections

    The Wireman part #887 : $25.00
    https://www.thewireman.com/antacc.html#3
    Matching section for the Butternut HF verticals for 20 meter matching -
    fully assembled with female and male UHF connectors for simple installation at feed point.
    ====
    Butternut HF-2V (80 and 40 meters)
    DX Engineering part number: BUT-HF2V
    Updated Instructions, Charts, Guides and Technical Information (2016, PDF)
    https://static.dxengineering.com/global/images/instructions/but-hf2v.pdf
     
    Last edited: Oct 4, 2017
    NH7RO likes this.
  10. W9GB

    W9GB Ham Member QRZ Page

    Calculating the ELECTRICAL LENGTH of Coaxial Transmission Cable.

    Coax Cable Physical/Electrical Length
    Calculating the wavelength by velocity factor of coax cable.
    by Karl Smith, N1GNN
    http://n1gnn.com/webData/CoaxVelocityFactorLength.html

    This worksheet calculates wavelength (W.L.), half wavelength and quarter wavelength of coaxial cable based on the velocity factor of said cable at a frequency of interest. If the dielectric constant (er) of the cable is know rather than the velocity factor (vf), that parameter may be entered instead.

    Remember that manufacturers published values for velocity factor are "nominal" and vary in "real life" from reality. It is not uncommon, for example, to see the velocity factor vary from one end of a 500' reel of coax to the other. Part of the problem is the inability of coax spooling machines to maintain the same tension on the cable when the reel is just being started (small winding radius) to when it is finished (large winding radius).
     

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