I do find that the use of ferrite on the coax line does break up the RF
current and solves many issues. It is, in my experience, the better way to
solve issues as opposed to implementation of extensive grounding and RF
shielding means. I've never been a proponent of generating good RF and then
employing a means to run it to ground. That just doesn't make good sense to
me.
To that end I believe we find radios today with inputs and outputs that have
wider bandwidth in terms of being able to have wider audio passband, the
ability to pass data and other high speed signals. The result is that some
of our data speeds are approaching RF frequencies and thus increasing the
susceptibility of RF getting into the radio or other devices.
I think this is also more prevalent where antennas are closer to the rig or
equipment in the house. I know many instances, due to space limitations or
other restrictions, where antennas are located in the attic or just above
the roof, hence these produce a very strong RF field at the operating
position. Some means is required to prevent the RF from entering the box
and ferrite on the cables as common mode chokes appears to be the most
efficient way.
73
Bob, K4TAX
----- Original Message -----
From: "Pa1ap" <pa1ap@nextchallenge.net>
To: <tentec@contesting.com>
Sent: Wednesday, May 16, 2012 12:58 AM
Subject: Re: [TenTec] RFI Issues
>I really like the document as shared and reading through it. Would
>appreciate your advice on the following rfi experience:
>
> recently I build an artificial ground to ensure rfi gets directed
> somewhere else. I wasn't sure it would fix the rfi issue but figured it
> was fun to build and never harms... after connecting the artificial ground
> to the rig there was little rf going through the artificial ground which
> suprised me a bit. I also noticed touching the chassis of rig, balanced
> tuner, power supply and other components changed the current. Then I
> decided to decouple all wires connecting to the rig using ferriet cores.
> Suddenly the rf current through artificial ground went up and touching
> chassis of previous mentioned devices had little to none influence on the
> current through artificial ground.
>
> Now the orion seems very isolated from eveything except the artificial
> ground tuner. Rf through tuner is stable and when I am working on 20m and
> up there is no issue anymore with rfi into the house nor my computer
> speakers. It was fun to learn something so fundamental and to realize I
> forgot more than I realized ;-) yes I have a compromised shack as it
> resides at second floor of the house and I am almost touching the apex of
> my dipole.
>
> The question I have: could I have done this easier through applying other
> techniques like described in the document? am I just fixing a sympthom
> instead of the root cause? I had two rfi issues; potential rfi into the
> mic and rfi into the audio equipment within the house. I am new in this
> area.
>
> Thanks and best regards, onno
>
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> http://lists.contesting.com/mailman/listinfo/tentec
>
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