Baseboard counterpoise/2nd floor RF grounding

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K3RW, Nov 13, 2016.

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  1. K3RW

    K3RW Ham Member QRZ Page

    Sorry to open up another thread about 2nd floor grounding. I've read tons of the '2nd floor' threads and I still haven't figured out this particular issue. Among several, I'll be using an EFHW for 60m.

    I read that I could run a counterpoise around the baseboards of the room. Given my shack location, that is likely my only and/or best option. So its either the MFJ-931 artificial ground box, or the counterpoise around the room idea--or maybe both. The question I have is--HOW?

    I've read a bunch of stuff on QRZ, Eham, etc. What I've understood is the counterpoise in this application needs to be 1/4 wavelength--per band. If I'm on 40m, then I know how long that 1/4 wavelength is. Problem I can't figure out is how to do multiple bands on the install:
    • Given it needs to be 1/4 wavelength per band, I would have many different wires around the floor if I work many different bands. Any considerations on spacing the wires/doesn't really matter/etc.?
    • And 1/4 wavelength per band--but a 1/4 wavelength at what? Center of the band? Lowest part of the band?

    One post mentioned 'selecting the right counterpoise' from the multi-band ones. Huh? Other than unplugging it, or somehow switching it, I'm not sure if one could even do that. Or if it is even necessary--a lot of threads have some dubious info on this.

    The early plan for RF grounding here was to connect all the station equipment grounds to a single point, then pass it through the window using the MFJ passthrough, and drop a stout copper wire to the outside faucet below. Problem is, it is just far enough to potentially resonate itself.
    • Do I skip connecting the ground wire from the tuner, to the cold water faucet, if I use the around-the-room counterpoise?
    The MFJ-931 provides an artificial earth and if I understand it correctly, it essentially tunes a counterpoise. I'm debating if I need/want this at all.

    • If I went the box route, would I just make one 1/4 wavelength one at the lowest frequency (say 60m) and just tune the box to 'shorten it' for higher bands? So I'd only use one wire for everything?
    I included a diagram that depicts what my current understanding is. I imagine the wires would be bundled closely together, or even in a PVC water pipe or plastic conduit. Am I on the right track?

    Presentation3.jpg
    And the final (!) question, if I am using a EFHW for 60m, the balun box has two posts--one for the 'hot wire' and another for an 'optional counterpoise' (har har har). But in this application, my counterpoise would be INSIDE and the balun would be OUTSIDE.

    So given my inability to do anything outside for a counterpoise, is there a way to bring it in?

    So would I be bringing in the balun counterpoise to the window pass-through, and connecting that to my new counterpoise system? I'm not sure how I would connect the counterpoise post on the balun, to my new system, or if I would even do it at all.

    73
     
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  2. AA7QQ

    AA7QQ Ham Member QRZ Page

    Your image shows the proper setup for a baseboard counterpoise setup.
    Personally, if the balun is outside, I would add a single random counterpoise there & add baseboard counterpoises inside for bands as needed.

    Ed
     
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  3. KD0CAC

    KD0CAC Ham Member QRZ Page

    You are getting confused , witch is easy with undefined terms .
    A few things to keep in mind , there are 3 perspectives when referring to ground / grounding ,
    1 - AC grounding
    2 - RF grounding
    3 - lightning grounding
    There is some overlap , but 1st need to be kept separate when the initial thinking / designing , then look at the overall combined system .
    It would seem there is another issue that you are combining , and this is where there is not an overlap - on the RF side - radials , baluns [ another chance to get confused - the term balun is used mostly in a general subject , but has specific definition = ba - balanced l un = unbalanced , an example twin-lead to coax ] .
    These last 2 are part of the antenna and kept at / or part of the antenna and generally not tied to other grounding .
    As an example , my personal way to look at , all antennas are dipoles or react like a magnet - you can not break a magnet in half and separate the 2 poles , you end up with 2 magnets .
    Again generally there are 2 connections to a antenna / Di-pole , twin-lead or coax and the feedpoint - connection to antenna , in this case lets say a vertical part one half of dipole and the counter poise radials , the half of antenna , at this point the feedpoint between those 2 parts need to be very close to each other , inches or less .
    Let's see where that goes ;)
     
    K3RW likes this.
  4. KA0HCP

    KA0HCP XML Subscriber QRZ Page

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  5. K3RW

    K3RW Ham Member QRZ Page

    Thanks, I had read it but found it difficult to implement in my situation goven the distance to any ground rod I can install or the electrical panel, etc. So the baseboard idea looks promising though I have yet to see how it is actually done in a picture.

    Somewhere a post referenced having to switch between the band specific counterpoises. i dont see how I could do that without a switch, OR using a long counterpoise and tuning it with the MFJ box... to prevent needing 8 different counterpoises to work muti-bands.
     
  6. K3RW

    K3RW Ham Member QRZ Page

    The 9:1 EFHW balun (or un-un, I'm not sure what it is, but it works!) would be outside the window pass-thru, though I'm not sure how much coax I'll run to the box from the window, if that makes sense.

    Not sure how I could do a counterpoise for it, if the box is up 20-30' and its dangling over a RV pad, lots of concrete, and ways away from a ground rod or anywhere I couldveven place one. And likely would end up with a resonant RF ground somehow given the even the shortest length I could make it. I've not seen an aerial counterpoise, but I did see something about using the roof. Or maybe a gutter. Hmmm.

    Only thought I had to remedy it would be to somehow connect the ground back through the window to an indoor baseboard counterpoise.

    It kind of is a bummer since it worked somewhat well for 60 and 160, depending on the length(s) I used, but with the 1/4 wavelength of either being very, very long I didn't see how I could do it without looping it around the room several times. I figured that was not advisable.

    Wish I had a better option than the baseboard counterpoise, but I'm not thinking I really do.
     
  7. AA7QQ

    AA7QQ Ham Member QRZ Page

    Try about a 20' counterpoise connected at the balun. Keep it outside. You might need more length, but it's a start.

    Ed
     
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  8. W8IXI

    W8IXI Platinum Subscriber Platinum Subscriber QRZ Page

    It's "both".

    You are currently in the "paralysis by analysis" mode and you need to move forward.

    My solution for years has been the MFJ artificial ground with random lengths of speaker wire arrayed around the perimeter of the second floor room which is my shack. It's only two or three wires. I don't remember how long they are. If you want to build your own tuner, QST had a nice counterpoise tuner project worth reading just a few months ago.

    No one here can see or fully analyze your situation. Don't view an antenna or counterpoise tuner as some kind of a bad option which, if you were a "better ham" you could easily figure out and compute a perfect first antenna for all of the bands you would like to work.

    It never happens that way. Good Luck!

    73, Mike
     
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  9. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    You don't switch the wires. Just connect them all to the ground post of your tuner or radio.

    Again, you are confusing electrical/lightning safety (ground rod) with RF ground (counterpoises).
     
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  10. K3RW

    K3RW Ham Member QRZ Page

    Sorry about that. I see my own confusion on the issues. At least one of the articles I'm read were intermixing both, as if one can use a ground rod for everything. One was using a ground rod for RF (?) and said so. For my vertical I'll use radials. But for these other types, the counterpoises appear to be a challenge. If I went solely on the balanced antenna route, I'd imagine it would be almost a non-issue.

    I'm really only concerned about the RF part. Lightning here is very rare, I'd guess maybe 2-3 times a year, and I would just unplug things rather than hoping an arrestor would work.

    Not sure what I can say about the electrical situation here though. I'll have to study it further. May be easy to manage here, I hope.
     
    Last edited: Nov 14, 2016

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