Astron PS and Your Ground

Discussion in 'General Technical Questions and Answers' started by AI5DH, Oct 29, 2019.

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  1. K5EMG

    K5EMG XML Subscriber QRZ Page

    I checked with my tester and the AC ground is not connected to the negative DC output, but you're right about other power supplies and about the complexity when you add to the mix several other device like amps and such. Unfortunately a lot of old devices like radios and amps doesn't complain anymore with modern regulations, and that's when issues start to cause trouble.
  2. AI5DH

    AI5DH Ham Member QRZ Page

    I totally agree with you, no argument.

    Finally a good question and you seem to understand. Hopefully I can do it justice with just words. There are 2 basic Bonding and Grounding best practices called Single Point and Multi-Point. They mean exactly what they sound like. Most commercial operators use Single Point. That means all services AC Telephone, CATV, Radio Coaxes all enter the building at roughly the same point and pass through a ground window where all are bonded together. What you get is a current free Ground Point. Very few hams can exercise this option unless you live in newer construction where today that is exactly what is being done, all services enter one point and a ground bar on a wall to facilitate ground connectors. Point here to make, the ground is current free which means noise free wiht absolutely no voltage between ground wires. Everything at the same potential.

    OK most hams have to use Multi-Point meaning ground appears in more than one entrance. You have to accept the fact you are going to create a loop, but that does not mean you have to be in the loop if you know how and what to do with your grounds. You want to SHUNT all Current around your station, so there is absolutely no outside current in your ground plane. So how do you do that? Pretty simple, you plan for it.

    So here is what you do. Where your coax enters you should have a ground rod or access to the ground electrode outside for you to bond the coax too. Run at least a 12 AWG conductor in with coax and maybe a second 6 AWG described later. Run the 12 AWG in with the coax to the 120 Volt Outlet your equipment is going to use. ond it to the Yoke of the outlet and leave the bare ground wire connected.

    If you want or need an RF Ground Run a second 6AWG conductor up to your equipment. Use 1-inch copper pipe as a buss bar to solder equipment grounds too if you just think you must have a Ground Bar that serves no purpose. Otherwise RF Ground is where the Outside Coaxes Terminates and references all the equipment to RF Ground.

    Some of you guys are pretty sharp and figured out what I am doing. I am make a pseudo Single Point Ground. I know I am going to have incidental contact between the two ground sources. Examples given such as a Tube Linear Amp. What you do is make that Bond intentionally downstream, and we connect at a single point. We SHUNTED the nasty Loop at the source where it enters and exits. So any circulating current enter 12 AWG from coax bond straight out on AC Equipment Ground. None flows through equipment Think of it like a busy road with lots of traffic with a single street intersecting to a cul-de-sac. You can play with your toys in the street with no fear of outside traffic mucking things up.

    You are left with a Current Free Reference Point free of noise.How you connect it together matters. If you fail to plan and lay it out properly, you will likely create ground loops.

    Here is how I open with new students to understand grounding.
    Bond Everything below dirt together.
    Bond Everything above dirt together.
    Bond the two halves together at one point.

    In short you have a choice. You can put yourself in a ground loop and suffer the consequences. Or you can take yourself out of the loop and sleep good at night.
    Last edited: Oct 31, 2019
    K5EMG likes this.
  3. K5EMG

    K5EMG XML Subscriber QRZ Page

    Got what you mean, I only missed to run a 12 AWG ground cable to my outlet yoke.
  4. WA7ARK

    WA7ARK Ham Member QRZ Page

    I would have liked to see you draw a schematc, but you keep ignoring my request... So let's use mine...
    Here it is again, with one difference. I have added the #12 wire you described as running from the wall outlet grounding screw to the outside ground rod at the entry panel. Care to explain how the RF currents or Noise Currents would be different with and without this wire?
  5. AI5DH

    AI5DH Ham Member QRZ Page

    Glad you understand. Really pretty simple stuff. Sounds like you know what to do now.
  6. AI5DH

    AI5DH Ham Member QRZ Page

    No we will use mine as it is much simpler to see what is going on. You put your equipment in a Ground Loop, and advocate doing so because there is no other way it can be done which I say BS. I do this professionally. Any questions. It is stupid simple to understand.


    For those that understand, it matters how the grounding conductors are arranged. Otherwise ignorance puts you in a loop.
  7. WA7ARK

    WA7ARK Ham Member QRZ Page

    Ok, Mr Professional. I took your cartoon, and annotated it with reality.

    Well, since you think I am ignorant, why dont you show how you combine the AC cord green wire and the Coax shield from my Radio Toy into a single conductor? Make it so that even I can understand.
    Last edited: Nov 1, 2019
  8. AI5DH

    AI5DH Ham Member QRZ Page

    I did, I showed you with a simple circuit drawing. I showed you How there is another way using Single Point Ground Connection. Like I said the difference is you put your equipment in a loop when there is another way every commercial operator uses. We tap the loop at one point for a reference. The circulating current flowing in the Ground Loop will not flow through you ground plane. Every ground is connected to the same point with its own dedicated conductor in radial fashion so it cannot share any current with anything else. Current needs an entry point and an exit point yo make a complete circuit for current to flow.

    Now go back to the drawing and open your eyes and listen. The Coax Shield, AC Ground, shielded cables, or whatever are all represented by the single line, All grounds go to a Single Point. No outside current or faults can flow through your equipment. The difference is my way just taps the loop in one spot only and from that point the equipment never sees Ground again. It is not in the LOOP like you advocate. Very simple to see.

    NEC Article 250.6 titled Objectionable Current deals with this application. 230.6 allows users to arrange ground conductors to prevent objectionable current. I am telling you and others how to arrange the ground conductors to do exactly that. Not only safer, but current free ground reference which means no noise. .
    Last edited: Nov 1, 2019
  9. W9WQA

    W9WQA Ham Member QRZ Page

    jfwiw, those caps are tied to the power supply ground which may or not be tied to the chassis.
    otherwise im not in the main argument! just having popcorn with the howdy doody bunch !!!
    N8VIL likes this.
  10. WA7ARK

    WA7ARK Ham Member QRZ Page

    Dereck, you are not making any sense.

    Start with an AC-line-powered ham transceiver in a box. It has a three-prong UL-approved AC line cord, with the green wire being the safety ground. The green wire is connected to the transceiver's chassis and to the fat pin of the wall socket. The fat pin is connected via the bare wire in the in-wall Romex to the houses' utility ground. The radio chassis is effectively grounded by plugging it into the wall. You, or I , or anybody else gets to choose anything else.

    Now connect a coax cable to the back of the radio. The outside of the PL259 socket is connected to the chassis of the radio. That electrically connects the antenna coax to the house ground. Run the coax to an ungrounded antenna in a tree. The Code requires a ground rod where the coax comes through an outside wall into the house, so you drive it and bond the coax shield to it. Code also requires that ground rod be cross-tied to the house's utility ground. You, or I , or anybody else gets to choose anything else if you want to obey the Code. That creates a loop with two earth grounds.

    Now draw me a picture of how you are going to do anything else, and still comply with the Code.

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