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Multi-Point Ground Implementation. Part 2

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KF5LJW, Nov 8, 2019 at 6:37 PM.

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  1. KF5LJW

    KF5LJW Ham Member QRZ Page

    After numerous emails with questions and support, I thought I would now show you another way to skin a cat that will completely take the AC Ground Loop right out of the house leaving you with pure Single Point Ground that is again very simple for anyone to implement and understand. All it takes is a little planning on your part, and a grasp of what Ground Loops are and are not. Really nothing more than simple series/parallel circuits laws and Ohm’s law.

    As discussed in the first thread when you bring in an Earth Ground at two different and use AC Power is going to create a Ground Loop forcing lightning and noise current through you home wiring. Just a fact. The Loop is completed when you connect anything AC powered equipment into the wall for power. Connection path is AC Ground to Equipment Chassis and out the Coax Shield to RF Ground Rod outside shack. The 14 or 12 AWG wire from your AC Breaker panel becomes connected to the outside ground rod your antenna coax shield is bonded too. As shown, we can and do take the radio equipment out of the Loop. But can we get the Loop out of the house?

    Some say it is IMPOSSIBLE, there has to be a loop made inside the house and nothing you can do about it. Some will say a hams cannot do SPG. I say they are full of it and cannot think outside the box. Run the AC circuit outside the house, not through the house silly.

    OK have a look at the one-line Grounding and Bonding wiring diagram below. Really not much different. Just a couple of minor tweaks we can make because we are running the 120 Volt circuit outside. Here is how it is done. Lay out a plan, hire an electrician (sparky) if you do not have the skills. Locate on the outside wall where you want to bring in the coax and AC circuit. Bring them in at the same area. You are going to want your Station Ground Bar as close to the floor as possible so both coax and AC circuit need to be as close to the floor as possible, and as close together as possible entering to keep conductors short. You and your electrician find the spot to bring in the Coax and AC Circuit. Instruct sparky to sink a rod right where the coax and AC enters as close to the house as possible. Trench in 6 AWG Bonding Jumper below grade from AC service ground, coax entrance, and out to the Tower or Antenna Mast.

    Now instruct sparky to run you a dedicated 20-Amp circuit from the Breaker Panel and run it in EMT outside the house near ground level. Your 6 AWG bonding jumper you used to bond the rods together will be right below following same route.

    Have Sparky mount a Junction Box where cables enter the house and use a Through Nipple so we have solid metal raceway pipe from Breaker Panel to the Yoke of the Wall Plate inside the shack. From the junction box have sparky take green AC Ground wire from Breaker Panel straight to the same Ground Rod where the Coax and Station Ground Bus are terminated. Then from Ground Rod run green AC Ground wire with circuit conductors to receptacle Yoke and terminate.

    OK with EMT ran listed as Ground, NEC does not even require you to run the green AC wire as the EMT acts as the conductor. However, we run a dedicated 12 AWG Green AC Ground wire along with our AC circuit conductors L and N.

    Or could even get creative and use direct burial cable ran inside a 1-inch copper water pipe used in place of the buried 6 AWG Bonding Jumper the Ground Rods together below grade. Either way gets the Loop outside completely eliminating any path for lightning and noise to travel through your house wiring. Exactly what earth ground is supposed to do unless you screw it up compromising the integrity.

    OK here is the twist I spoke of earlier. Since we ran a dedicated AC circuit outside, we can implement the Station Ground Buss, Antenna Discharge Unit (ADU or Surge Protector), and receptacle a little differently than before. Most likely you will not need a Power Strip because you told sparky to equip you with a Quad Outlet in a Metal Outlet BOX mounted onto your Station Ground Buss of choosing along with the ADU. Example use a copper buss bar large enough to mount the ADU and Outlet onto. Drill the Buss Bar to feed the Outlet Box straight out the rear going outside through Nipple penetrating the wall. You could also use ¾ Plywood with galvanized sheet meter secured with contact cement or screws. Or you could even use a short piece of ¾ copper water pipe. Figure it out

    That’s it you’re done. Not only have you removed your radio Toys out of any Ground Loops, you have also moved the Bad Loop outside where it belongs carrying faults around your house, not through it. You have a by the book Single Point Ground and operating like the big boys. Just as effective because there is no place for lightning to go through your house wiring. There is no ground inside to go to, we kept it all outside before it can even enter. What was done outside can more than handle anything Mother Nature or Man can throw at it. You are left with a rock solid SPG clean and free of any noise.

    You will not need to bond anything to the Station Ground Bar that is AC Powered because that connection was made as soon as you plugged it in. Example a Linear Amp with a Coax Jumper to the ADU. That gives you two bonding jumpers already. Adding a 3rd bonding jumper does not gain you anything. Wont’ hurt, but will not help either and is ugly. Only exception I can think of is an Antenna Tuner, and I would hesitate even doing that because the job is likely already done for you if you used a Coax Jumper to ADU. The Coax jumper is your Bonding Jumper. Adding another one does not gain anything except lower impedance which is not important as the short coax jumper impedance is low enough already. With No AC power, really nothing to short out inside TUNER requiring a larger conductor to clear the circuit breaker in the AC Breaker Panel

    Hope that helps some of understand what you are trying to accomplish. Get it right and not only is it safe, it also leaves you a squeaky-clean AC, RF ground to operate with free of Common Mode Noise. You get the best of both worlds like the pros do.

    So don't let anyone tell you hams cannot implement SPG because it is stupid simple to do. All you have to do is plan it out.

  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Ok, now you are just going into the realm of silly [edit] though the example is instructive!

    Easier to just demand that every ham have their power, phone and cable systems ripped out and reinstalled outside the shack window. Or, that they all rebuild the house to put the shack adjacent to the service/SPG entrance. Or buy out the neighbor, have the house demolished and a purpose built radio facility built. sigh.

    "A multi-point ground is dangerous". So is plugging in a toaster, or installing electricity in a dwelling. Hundreds of millions of homes had radios with antennas, and TV's with antennas that were never ground, bonded, etc. over the last century, and there was no plague of destruction and death. :)

    [edit] Your advice is overall quite helpful and have raised understanding in the Zed community. However, please back down on the drama and absolutist declarations a bit! Practicality and cost effectiveness are major considerations for most hams. Thanks, bill.

    [edit] p.s. Your recent example of 'shorting the house ground loop" is clever, and I don't think has been suggested before here.
    Last edited: Nov 8, 2019 at 7:01 PM
    WR2E, NN4RH and NH7RO like this.

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