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BNC to Binding Post antenna configurations?

Discussion in 'QRP Corner' started by VE7JBX, Aug 30, 2017.

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  1. KL7KN

    KL7KN Ham Member QRZ Page

    [​IMG]
    If I may suggest. You observe a pair of holes in the image above - one under each jack.

    Lace a split ring (like you use to hold your keys) thru each of the holes. Then, tie the antenna wire to the ring, leaving a short span to attach to the jack. This will take the stress off of the jack post and will make it easier to hoist the adapter up a pole / into a tree / etc.

    Best of luck on your antenna journey.
     
    KA0USE and WN1MB like this.
  2. VE7JBX

    VE7JBX Ham Member QRZ Page

    Thanks for the suggestion, Don. Good idea. If this looks to work I'll probably rig that up.
    For this first quick try I'll probably pass on that. My dipole arms I carry in my QRP kit are all done with 0.157" male bullet connectors - I carry a SO239 which has short leads off it to matching female connectors, and usually screw that on the end of my coax and can just plug in the matching dipole arms for band.

    But it just so happens, those 0.157" bullet connectors are an exact fit in the ends of the screw posts. Simple and if there's excessive strain they'll just pull out.

    I'm trying this on my EK-1C, by the way. Been getting better at using it (and improving a bit with my lousy CW, too). Made a solid contact into Rarotonga with it on 20m, earlier this week. Not so bad on 5W with current SFI...
     
  3. VE7JBX

    VE7JBX Ham Member QRZ Page

    Results of a quick try at lunch today.
    Config 1, 20m elements to binding pots then up into nearby trees (~8' up at ends). Called QC on 14059 kHz. RBN spots: Just one, VE7CC, possibly ground wave, @ 14dB. So, signal clearly getting out. RX test... JT65 strongly heard. 14100 kHz beacons: W6Wx heard @100w, 339.

    Config 2: Same 20m elements, fed by coax in inverted-V, feedpoint about 8' up (i.e. same height as antenna ends in Config 1), same orientation of elements as Config 1. CQ on 14059 kHz.
    RBN spots: VE7CC, 12dB; W7MRF, 6dB; Ku7T, 2dB
    RX: no observable difference from Config 1

    Trials were ~15 minutes apart. No tuner on my system; wires are cut to resonance for inv-V configuration.

    Observations: VE7CC was only station reporting both configurations. They were within 2dB but may not represent normal skywave propagation. Config 2 (traditional inv-V) did show more RBN spots.

    Overall, there was no obvious difference between the two. The traditional inverted-V is actually easier to set up though and can be readily done with feedpoint raised up more. In a pinch though it looks like the direct wire works fairly well - at least, no immediately obvious loss in TX or RX compared to similar height inv-V.
     
  4. KM4DYX

    KM4DYX XML Subscriber QRZ Page

    Thanks for the report. Here is a link to a technical report on the PRC 64, a QRP "patrol" HF rig used in Vietnam, if you are interested. The 64 used a linked dipole antenna connected directly to the rig in a V config. Lots of good info about field testing in Nam.

    http://www.militaryradio.com/spyradio/prc-64_final_report.pdf

    73,
    Al
     
  5. VE7JBX

    VE7JBX Ham Member QRZ Page

    Al, thanks! That looks like it should be an interesting read.
     
  6. KM4DYX

    KM4DYX XML Subscriber QRZ Page

    One more thing, 20 meters is going to be tough with a low antenna. Perhaps 40 meters, with the high angle radiation you're getting, would yield more contacts.
     
  7. N1OOQ

    N1OOQ Ham Member QRZ Page

    For what it's worth, 3/4 inch window line and binding posts are spaced the same distance apart... 3/4 inch.
     
    KC8VWM likes this.
  8. VE7JBX

    VE7JBX Ham Member QRZ Page

    Yes, I assume so... will give that a try in near future I hope. Have previously found that even a 10' feedpoint on inv-V 40m works really well - had not expected that.

    Off on a hunting trip next week and will have the QRP rig along for something to do in evenings at the cabin... will likely have it on 40m then with lots of time to try.
     
  9. N2UHC

    N2UHC Ham Member QRZ Page

    That's similar to the antenna I have as part of my portable 20M station in a bag. It consists of a feedpoint with SO-239 and two lengths of ~16 1/2' wire cut to resonance at 14.060. I can set it up as a dipole, inverted V, sloper, vertical, or even "upside down inverted V" aka a V antenna, though the inverted V is a bit more practical since you only need to get one rope up in a tree. But the versatility of it means that I can set it up however the local terrain might allow me to best get an antenna up.

    I've done this to make a vertical antenna with the setup described above. At first I had it set up with two extra wires used as ground radials, but to be honest I don't notice much difference between using one and three. Conventional wisdom says that it becomes directional in whatever direction the radial is pointing, but in practical use I've managed to make good QSO's off the back side of it as well. Not that I use this configuration much, though, usually I set it up as either a sloper or inverted V.

    I don't think I'd try this. Ladder line is high impedance and the two wires of the feedline are spaced apart a ways. Most speaker wire is spaced very close together so I think it would have an extremely high impedance. The closer the wires are the more interaction they're going to have, and with how close speaker wire is I just don't think it'd work very well. However, others who are more knowledgeable about twinlead and ladder line might have other ideas.
     
  10. N6MST

    N6MST Ham Member QRZ Page

    I did EXACTLY this a few days ago. From Bakersfield, CA the reverse beacon network picked me up in SC, PA, WA, NV, CA and western Canada. Not bad for some cheap speaker wire.

    Edit: On SSB I confirmed contacts in CA, AZ, CO, and MN. All with 10 watts from my KX2.
     
    VE7JBX likes this.

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