Yes, Jim, your suggestions and the installation of proper baluns and/or
common mode chokes are the correct answer. He doesn't realize that!
What's even more, common mode noise also raises his receive noise floor.
Again, proper installation and the proper use of a balun or CMCs should fix
the problem. Far,........, FAR too many hams do not properly reason
through a problem but just "throw" a ground into the mess.
Dave - WØLEV
On Tue, Jan 21, 2025 at 5:52 AM Jim Brown <jim@audiosystemsgroup.com> wrote:
> On 1/20/2025 7:09 PM, Bob WA2SQQ wrote:
> > He swears that if the noise increases when the shield is connected,
> that’s
> > a positive indication you have an abundance of common mode noise.
> >
> > I’m not so sure this is a valid test. Comments?
>
> It's certainly an indication of failure to do proper grounding and
> bonding. Coax shields should go to a lightning arrestor where they enter
> the building, ideally on the exterior wall of the shack. The arrestor
> MUST be bonded to grounding for the building, which, BY LAW, must be
> bonded to all other grounds in the building, including entry for power,
> telephone, CATV, satellite dish, and any other antennas.
>
> On the operating desk, all parts of the station must have their chassis
> bonded together by short, fat copper, and that must be bonded to the
> grounding for the building at the closest point. And all cable shields
> should be bonded to the chassis AT THE POINT where they enter equipment.
>
> If you've done all this, any common mode current on the shield is going
> to go into that ground bus to all of the driven rods, not into your
> radio or other equipment in your shack.
>
> Study N0AX's excellent ARRL book on the topic, to which I contributed
> extensively, and/or the pdf of slides for talks I've given at Pacifcon,
> Visalia, and to several ham clubs.
>
> 73, Jim K9YC
>
>
>
>
>
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>
--
*Dave - WØLEV*
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