Astron PS and Your Ground

Discussion in 'General Technical Questions and Answers' started by KF5LJW, Oct 29, 2019.

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  1. KF5LJW

    KF5LJW Ham Member QRZ Page

    Are you really that ignorant? Current cannot flow in an open circuit.

    No i cannot make the loop go away that is formed by the bonding jumper in the dirt, and the green 12 AWG from the breaker panel. You do not have that luxury with a multi-point ground. But what I can do is SHUNT the Loop, and remove my equipment from the Loop by only referencing the loop at a at a Single Point . The Radio Coax and all the power cords for things like DC Power Supply, Linear Amp, Desktop Computer, or anything you want all have a dedicated Ground Wire terminated too one Single Point, right where the coax is bonded outside the ground rod. It is impossible for current to flow in a open circuit or single point ground

    If I take two wires, bond them together at one end only; how much current is flowing? If I take 4 wires, bond them together radially at one point only; how much current flows?

    Answer is None. Current cannot flow in an open circuit. A first year student learns that first day when introduced to Ohm's Law.

    You can chose to put yourself in the Loop, or you can take yourself out of it with a Shunt. RF Ground is not in the shack. It is in the dirt where your coax coax is terminated to the Ground Rod, and now all your power cords are terminated with dedicated conductors to the same spot as the coax. That is the beauty of a Ground Window, we only terminate radially, not serially daisy chained in a loop.

    If you understood that, you could fix that mess you made real fast.
     
    Last edited: Nov 1, 2019
  2. KI7TGX

    KI7TGX Ham Member QRZ Page

    I am enjoying this discussion, which is mostly civil; I think both WA7ARK and KF5LJW are making good arguments. As I am relatively uninformed, I am learning from both.

    But let me focus the discussion for a bit. Below is a schematic as I understand things:

    IMG_2075.jpeg

    So I think what ARK is saying (not to speak for him) is that even though you have added a low resistance path from wall outlet to the shack rod, current still flows, maybe less, but still some, on the parallel path through the radio. Current flows on all available paths, not just the one of least resistance. So that is issue 1 as I see it.

    Issue 2: ARK says it is impossible to eliminate this second loop because he has so many AC powered accessories. I think LJW is saying (again, not to speak for him) is that if your single source of AC connection is the DC power supply, floating the negative will cut this second loop. Is there a reason that this is not correct?


    Again, I am not taking sides here, just trying to learn. Thanks to both of you for trying to be (mostly) constructive.

    Thanks!
     
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    All this thread is doing is confusing us old farts.

    You are not convincing on how to do it wrong or right.

    That is why I do it all left. None of the above is correct. :rolleyes:
     
  4. WA7ARK

    WA7ARK Ham Member QRZ Page

    Good luck with that. So far you have not been able to draw a comprehensive schematic, or write a comprensible paragraph.

    Good, we agree about that...

    Nope, that diagram is much too simplistic and doesn't show how every piece of equipment in the shack has two connections, one through its line cord, the other through coax, or through a grounding stud on its chassis.

    No it doesn't.

    So you are using "amateur radio operator" as a perjorative? If you are so superior, why do you post here? ... and yes, there is no way not to create a loop if complying with code without cutting the ground prong off all the line cords. Good luck with that. If you have a networked computer incorporated into the ham station, it cannot be done, anyway.

    Sure I can see it. I described it, diagrammed it, talked about it, explained it and have stated it really doesn't matter if it is there. Only you, the professional, claim that it can be eliminated, but so far, you have not shown us how?
    The loop stems from the fact that every piece of Ham equipment has two connections to the outside world. One through the line cord, the other through the chassis/coax which ultimately is connected to an outside ground rod. Bonding the outside ground rod to an electrical outlet does nothing to help that; in fact it muddies the waters still more because you now have created a secondary loop inside the bigger preexisting loop.


    Yep, I did that.


    Yep, I did that.



    Yep, I did that.


    No, all you did is add a #12 wire in parallel with some line cords. In the process, you created yet another loop.

    All of my radio toys are bonded using a short braid to a copper bus bar using the ground post placed there by the manufacturer of the gear. That bus bar is connected to the outside ground rod nearest the building with a short, fat wire.

    It sounds to me that you think this is ugly, and should eliminated, leaving only the coax shield(s) to provide a connection from the ham toys to the external RF ground. You think that is best practice?

    You call that external ground rod a "SINGLE POINT GROUND". It is not, because the items connected to it have alternate paths to other ground rods... i.e. it is part of a loop, as you admit.


    No you dont, there are multiple paths to get to various ground rods.

    God protect me from "pros" like you! You don't understand basic circuits, nor can you draw a simple schematic. You are arrogant, condescending, and apparently cannot stand being challenged...
     
  5. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Even in the latest scenario from Dereck there is still, for instance, the connection from the amp to the coax ground via the coax AND the ground from the power cable with ground pin to the outlet and now both through the breaker box AND now also through the 12 ga wire added from the outlet to the coax ground outside.

    How does this help? Is Dereck proposing we remove the AC line cord ground from all the equipment, including the amp? (Via pin removal or a two putting to three prone adapter)

    ?
     
  6. WA7ARK

    WA7ARK Ham Member QRZ Page

    Good luck getting him to 'splain it!
     
  7. KF5LJW

    KF5LJW Ham Member QRZ Page

    OK you are blind, it shows all connections and if you could see there is only ONE CONNECTION, not TWO. The Power Cord Ground (the pin at the end of the cord, is connected to the same point electrically as the COAX.
     
  8. KF5LJW

    KF5LJW Ham Member QRZ Page

    OK good eye and you are starting to catch on, but your circuit is incorrect. You show the coax ground tapped between the radio output and ground rod. That is not correct. The coax is bonded directly to the ground rod, and the antenna is beyond that point and has nothing to do with the circuit. Show the coax extending from the radio to the ground rod. It matters where you connect things so you do not create a loop.

    OK in RF Engineering we make what is a Ground Window so we can create a Single Point Ground. That ground window in reality is something like a Hatch Plate, A Ground Bar, a short section of copper water pipe, or in the this case a Short 12 AWG Jumper Wire ran from the ground rod, to the AC Wall Yoke. You can use larger wire if you want. As long as we reference all our grounds to the Ground Window Bar with a dedicated Ground Wire, all connections are to a Single Point electrically. In this case a 1 to 3 feet section of #12 AWG wire that runs from the ground rod to Wall Yoke.

    Will circulating current flow through the wire I am calling the Ground Window. Absolutely yes. In that short section of wire, 1 to 3 feet there is effectively no resistance between any two points of the Ground Window Bar we used to create a Ground Plane. The Ground Window is an Equipotential Ground plane where the impedance between any 2 points along its length is 0 OHMS.

    If I have current flowing through 0 Ohms, what is the voltage developed. You had better say 0 Volts or Dr Ohm is going to slap you silly. So if I run dedicated conductors to the ground window, what is the voltage between any two conductors? The answer is 0 Volts, they are all connected to the same point electrically. Without a voltage difference between equipment, there cannot be any current flowing because there is no voltage pushing current into an open circuit. All our dedicated Ground Cables are an open circuit that only go as far as the chassis. They are only bonded at one end, not both. Current cannot turn around and come back the same way it came in. It has to have a point to enter, and another to exit.

    OK now lets put the equipment in the Loop and mess things up as much as we can. We start by not completing the SHUNT wire I used as the Ground Window Bar and allow circulating current to flow through the radio equipment. The loop or Ground Window you are now making begins at the ground pin plugged into the wall socket. It travels up the AC power cord for some 6 to 10 feet or however long your power cord is. Add additional wire if you use a Power Strip so you can have more than 2 plug-ins. From your Power Supply, Desktop, or Radio chassis the ground is fed serially through your gizmo you plugged into the wall out to the radio through another few feet of wire. Once to the radio the coax completes the loop when terminated to the ground rod outside the shack. It had to go through 10's of feet of wire and cable serially through your equipment to complete the loop circuit. The Ground Window plane opened up from 1 to 3 feet to 10's of feet. That cable length now has considerable more resistance, and thus when current flows, a Voltage will develop across the Ground Plane and allow current to flow.

    Understand now?Look again at the circuits I made earlier clearly demonstrates what is going on. The Radio only has a single point of connection to the loop. The other way is through your radio equipment.

    To make it really simple, W7ARK wired his ground serially through his equipment. My way connects radially outside the loop. Whatever current is circulating in the loop, cannot circulate in the radio equipment connected radially.

    [​IMG]
     
    Last edited: Nov 1, 2019
    N8VIL likes this.
  9. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Does an amp for instance not still have two ground connections? Even with the low resistance Sunny from the outlet ground to the coax ground ride outside don’t you still have that outlet ground going back through the ground wire to the breaker box?

    A picture really would help. Be sure the picture includes the ground wires of the AC power wires from the amp, etc. Or are you removing those? I am not clear on that.

    Thanks.
     
  10. KF5LJW

    KF5LJW Ham Member QRZ Page

    Yes good question and the answer should turn on the lights for you. Yes you have two connections to ground. One from the Green AC wire to the chassis of the Amp or gizmo. Then on the chassis you have a SO-259 Antenna connector with the coax going out to ground rod. The shield of the coax completes the loop with a second connection Can we agree that is exactly what you and everyone is referring to are referring to? I have already drawn the circuit schematic, you are just missing a key point.

    If we can agree on the above point; tell me what happens if we bond both ends together? Not a trick question. We connect the AC Ground to the end of the coax outside on the ground rod. That is what we are doing with the jumper. We take the Point where the 12 AWG AC ground from the Main Breaker Panel ground bus to the yoke and bond it to the ground rod where the coax is bonded. We put a dead short from the yoke to the end of the coax. The Green Wire from the AC Panel is terminated to the same point as the Coax shorted together. A Single Point Electrically.

    Thus when we take two wires, bond them together at each end we have made a single conductor out of two parallel conductors. That is not a loop, that is a radial connection to the loop. I intentionally short the loop out and make a shunt.

    Does that turn any lights on? Think of it like a loop highway encircling the city with current flowing around the loop, err I mean current. Now we intersect the loop at a right angle with a short street we call a cul-de-sac that goes no where. No traffic, err I mean current can flow in our cul-de-sac. We have not provided a path for traffic err I mean current to flow. .
     
    Last edited: Nov 1, 2019

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