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Thread: Long Ground Run

  1. #1

    Default Long Ground Run

    I got my first HF radio for Christmas. It's an IC-7300. I've been limited to playing with 2 meters on my mobile until now so I am more than excited. It's been a long time coming.

    I have a question about running ground outside to a rod to get a ground bus. My radio will be set up in the office on the second floor of my house. So it's a pretty good run down to the ground to set a rod. And the wife isn't going to let it run across the floor or out a window or anything, I'm probably going to have to take it up into the attic and then over and out, so it could be 50 feet of wire or more for me to get out to a ground rod.

    Is that too far to run? I don't really know enough to know if I should be scared of a wire that long or not. Are there other options?


    Thanks!
    David
    K5DBC

  2. #2

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    You won’t need a earth ground at all if operate barefoot.

  3. #3

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    Quote Originally Posted by AC5PS View Post
    You won’t need a earth ground at all if operate barefoot.
    Can you elaborate? How do I do that safely? Sounds like something maybe not for those like me who don't know what they're doing.

  4. #4

    Join Date
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    Here are a couple things to look at. Apparently grounding is a highly contested topic in some forums. Keep leads as short as possible. I hope you find these items helpful. It's a start at least...
    https://www.mikeholt.com/instructor2...498-sample.pdf
    http://www.repeater-builder.com/tech...o-bonding.html

  5. #5

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    Quote Originally Posted by WZ7U View Post
    Here are a couple things to look at. Apparently grounding is a highly contested topic in some forums. Keep leads as short as possible. I hope you find these items helpful. It's a start at least...
    https://www.mikeholt.com/instructor2...498-sample.pdf
    http://www.repeater-builder.com/tech...o-bonding.html
    Oh goodness, I'm new around here I don't want to hit one of *those* topics. I had no idea. I've been around enough forums to know what happens.

    I'll let it go and try to guess what to do then. Hope I guess something safe...

    73
    K5DBC

  6. #6

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    To be completely honest with everyone here, I've NEVER grounded any of my radios I also run a 100w rig.

    RF is a complicated beast. There are many reasons for grounding ranging from static discharge so a pattern don't distort and RF noise elimination to keeping you alive in the event of a hardware fault. That said, ask ANY mobile operator sitting on rubber tires how necessary earth grounding is to getting on the air! Admittedly, in a mobile, you are in a faraday cage and not making physical contact to any ground yourself, so you will not become the filament of the "fault light bulb" when things go awry. Grounding is a safety and pattern thing, not a strict necessity to effective radio operation. Same applies to base operation. If your body is not in contact with a grounding path if and when a fault happens, you may get a tingle but you will not die (barefoot). If, however, something goes wrong and your body bridges the gap where current can flow between your broken radio and ground, lets hope heaven doesn't have an HOA that regulates antennas! Ground paths of the length you speak of can create their own problems with respect to circulating currents and resonances, and that ground wire will be a part of the antenna, both receiving and transmitting. Not a good thing on any kind of day.

    What I would recommend for anyone in your situation is to use a linear power supply (thus isolating your radio from the line voltage via transformer windings) and stay far away from the ends of the antenna where the RF voltage is highest. Whatever antenna you choose should be DC grounded to prevent pattern distortion from static buildup, whether via loading coil to mounting structure or with a discharge wire. A discharge wire will require a ground connection of some type. Being you are on the second floor, I would suggest a 10M ohm resistor (attached at the antenna) to the mains ground via wire to the nearest outlet ground with an RF ferrite bead on the resistor lead (on the side opposite the antenna). The high value resistor will be enough to discharge static electricity and the ferrite bead will keep the RF (that makes it through the resistor) off the mains. With that, keep your arms away from ground sources when your hand is on the mic.

    As for the rating of that resistor, most feed points are at the point of highest current and lowest voltage. With the resistor at the feed (rather than at the tip) I would expect a quarter-watt resistor to be just fine for a 100w radio. If you are using an end-fed with a 9:1 or better balun, IGNORE THIS lol, it will fry from the voltage.

    [EDIT] many CB radios that i've tore apart have had a high value resistor across the antenna jack. I can only assume to discharge any static buildup that may occur between the antenna and vehicle body. Same concept here. Perhaps your radio already has this. If it did (ohm it out) you could just add a wire from mains ground to the radio case and use an RFI suppression toroid or clip-on on the ground lead by the radio.

    As long as you combat static pattern distortion and ensure you will never become the conductor between a loaded gun of a radio and a source of ground, you will be just fine.

    {edit again] perhaps 10Mohm is a bit extreme. My icom has a dc resistance of 32kohm at the antenna port. Forgive the long-winded nature of this. Thinking out loud as I process this.
    Last edited by brandon lind; Fri 8th Jan 2021 at 04:16.

  7. #7

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    Thank you so much bandon for that post. So basically I'll be connecting the ground lug on the power supply and the ground lug on the radio to the mains ground and that will take care of safety and then I don't really need to worry much about RF grounding at my low wattage is what I'm picking up from you.

    I've got a DX-80 off center fed dipole antenna. I haven't put it up yet, hoping to get to that this weekend if the weather doesn't get too nasty. I've got room to flat-top it but it will take me a bit to get things together to put it up in the trees so I'm going to start with an inverted V for now so I can at least turn on the radio.


    A discharge wire will require a ground connection of some type. Being you are on the second floor, I would suggest a 10M ohm resistor (attached at the antenna) to the mains ground via wire to the nearest outlet ground with an RF ferrite bead on the resistor lead (on the side opposite the antenna).
    This is interesting. How do I connect it to the antenna? There are two wires coming off the balun, do I connect one end to one of those? Or to the coax where it goes in? Do I have to run it in to the mains ground or can I run it straight down the side of the house to the ground? Or is this something I'm building at the radio end and I'm just misunderstanding.

    Sorry for my confusion. I just want to make sure I understand you right.

    And what about lightning? I'm quite lost here and I don't want to do something stupid.
    Last edited by K5DBC; Fri 8th Jan 2021 at 04:28.

  8. #8

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    Quote Originally Posted by K5DBC View Post
    Thank you so much bandon for that post. So basically I'll be connecting the ground lug on the power supply and the ground lug on the radio to the mains ground and that will take care of safety and then I don't really need to worry much about RF grounding at my low wattage is what I'm picking up from you.

    I've got a DX-80 off center fed dipole antenna. I haven't put it up yet, hoping to get to that this weekend if the weather doesn't get too nasty. I've got room to flat-top it but it will take me a bit to get things together to put it up in the trees so I'm going to start with an inverted V for now so I can at least turn on the radio.




    This is interesting. How do I connect it to the antenna? There are two wires coming off the balun, do I connect one end to one of those? Or to the coax where it goes in? Do I have to run it in to the mains ground or can I run it straight down the side of the house to the ground? Or is this something I'm building at the radio end and I'm just misunderstanding.

    Sorry for my confusion. I just want to make sure I understand you right.

    And what about lightning? I'm quite lost here and I don't want to do something stupid.
    Your confusion is likely due to that being a creation of my imagination. I highly doubt anyone has done that as grounding to the radio is usually sufficient (most rigs now that I think of it have such a discharge resistor). I have, however, had a few crappy cb radios that did not have a resistor to discharge static buildup in the center conductor so I suggested that as a means to bypass that deficiency. I am guessing (with certainty) your radio will have such a discharge path for static buildup and you can disregard that idea. I still recommend the RF choke ferrite though as you dont want the ground becoming a part of the antenna.

  9. #9

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    Thanks again Brandon.

    This seems to be a large source of confusion for me lately, the difference between theoretical idea about ground and practical ideas about what people actually do. It's the latter that I'm after, but the former seems to be a much juicier topic for those making blog posts and web pages.

    The documentation that came with my antenna did say to be sure to include a choke on the line. It recommended wrapping several coils around a plastic form.

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