[Elecraft] Bonding

[Radio Amateur N5GE]

On Tue, 19 Jan 2010 18:27:27 -0800, "Jim Brown"
<jim at audiosystemsgroup.com> wrote:

Jim,

Thanks for that explanation of grounding methods.  I got at least one
of them right; I have a 1/2 inch copper pipe that runs along the back
of the operating table that all of the equipment on the desk is
grounded to.

73,

Tom, N5GE

n5ge at n5ge.com
K3 #806 with SUB RX, K3 #1055, PR6,
XV144, XV432, KRC2,
W1, 2 W2's and other small kits

1 K144XV on order

http://www.n5ge.com
http://www.swotrc.net

>On Tue, 19 Jan 2010 17:55:04 -0500, Don Wilhelm wrote:
>
>>I agree too, but would like to clarify that the "bonding" should not be 
>>a "helter-skelter" connection of one piece of equipment to another.
>>The most effective way of accomplishing that is to connect each piece of 
>>equipment in the shack to a common point (which may be optionally 
>>grounded or connected to a low impedance for RF (mother earth ground is 
>>only for lightning protection and personal safety, not RF grounding).
>>That type of bonding connection is often referred to as a "star" 
>>configuration - as opposed to a 'daisy-chain' where the connection is 
>>from one piece of equipment to another.
>
>There are really at least three different issues being addressed here. 
>One of them is bonding for lightning protection and power system safety. 
>The bonding that I was talking about to solve this issue is specifically 
>aimed at solving what I suspect are pin 1 problems in the interconnected 
>equipment. So the function of the bonding I recommended is to provide a 
>low impedance path from chassis to chassis, so that RF is more likely to 
>flow on the bonding conductors, chassis to chassis, than on interconnect 
>cables (audio and control) into the circuit board and into the circuitry 
>(by the pin 1 problem). That's also the reason for ferrite chokes on the 
>interconnect cables. 
>
>I certainly agree that a very low impedance bond of all equipment to a 
>single point is a good idea. BUT -- I don't want the path from computer 
>chassis to rig chassis to be any longer than necessary -- I don't want it 
>to go to the center of the star and back, for example. I've seen this 
>"star" approach implemented with a piece of copper pipe that runs along 
>the back of a radio bench, with a dozen or so wires connected at points 
>that are 6-10 ft apart. By contrast, my laptop sits on my operating bench 
>between two K3s, and there's a short piece of #10 braid going to both 
>rigs. The third reason for bonding is to minimize the audio voltage from 
>chassis to chassis that is caused by leakage current in the power system, 
>and that gets added to signal for any unbalanced connection between 
>equipment. By bonding that equipment with big copper, we minimize that 
>voltage (and divert the current away from pin 1 problems as well). 
>
>As for my lightning protection bonding -- THAT'S where I implement the 
>star. The rigs are bonded to the power outlet green wires with a short 
>piece of braid (outlets are just below the bench). The power outlets are 
>bonded to the coax entry panel, also just below the bench, which in turn 
>goes to a half dozen ground rods. There's also a lot of coax routed 
>through various switches to the coax entry panel (with feedthrough 
>arrestors). That provides a DC bond, but those coaxes have a lot more 
>inductance compared to the short braids. The power outlets run in EMT 
>(thinwall steel conduit) back to the power panel, which has three ground 
>rods of its own, on the other side of the small building that houses my 
>shack, and some #4 copper runs around the perimeter of the shack to tie 
>the ground rods together that way. 
>
>Does this clarification allay your concerns?
>
>73,
>
>Jim K9YC
>
>
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