Re: Help Request - RF in the shack

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From: Curt Milton (wb8yyy@yahoo.com)
Date: Sat Jul 12 2003 - 18:31:04 CDT


Yes Mark a lot of us have delt with this!

I am suspicious this is happening on some bands but
maybe not all of them. and you said your coax fed
antenna is clean ... i use a ladder line fed antenna
particularly on low bands. let's see i have a ferite
core on the lead between my paddle and my rig, and
also on my desk mic that has a preamp. so i have
experience this ...

i am suspicious it is RF being radiated by your
feedline or ground connection on band(s) where you
have a high impedance. i suspect the impact is
diminished the further you get from your operating
position? yes speaker leads on stereo units being
long often act like hf receive antennas. i am just a
little surprised for pc speakers since they are
typically shorter.

one possibility is if you ground connection is longer
than say an eighth wavelength on some operating
frequencies - well its not ground anymore its an
antenna! if you can't make it shorter, you can add a
parallel cable to avoid conditions when ground lead is
roughly a quarter wave - this is the worst condition.

you can try treating your offended electronics with
ferite cores - but do an inventory of everything in
your house effected to see if its close proximity to
your rig.

curt wb8yyy
--- Mark <rburton2@midsouth.rr.com> wrote:
> Hello all,
>
> A few weeks ago, I asked the group for direction on
> a limited space
> (restricted subdivision) antenna. The overwhelming
> majority recommended an
> EDZ. I constructed an 88 ft EDZ and it works great.
> I can use it on all
> bands from 80 thru 10 including the new 60M band.
>
> All this cheer aside, I have a little problem. I
> have RF in the shack, and I
> wonder about other places.. I am running low power,
> (1-25 watts) but it gets
> into my computer speakers. No problem with the TV
> (cable), however I wonder
> about the neighbors and their stereos etc.
>
> The shack is on the ground level in a house. I am
> using a B&W KW Low Pass
> filter between the rig (Kenwood TS-850) and the
> tuner (Heathkit SA-2040
> 80-10 Tuner). The rig and tuner are well grounded. I
> am feeding the EDZ with
> about 70 feet of 400 Ohm (#14 AWG) window type twin
> lead and a cool
> weatherproof ladder line to wire center insulator.
> The antenna is in the
> shape of an inverted-V. The apex is about 30 feet
> and the ends are about 10
> ft above the ground. The ends are not near the
> shack.
>
> I also have a coax fed 20-Meter dipole at about the
> same location. I have no
> shack RF issues with this setup. I would greatly
> appreciate any feedback on
> ways to minimize / eliminate the RF in the shack
> issue.
>
> Thank you,
>
> Mark
>

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