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[RFI] MOre RFI

To: <rfi@contesting.com>
Subject: [RFI] MOre RFI
From: tduffy <tduffy@sygnet.com> (tduffy)
Date: Mon, 02 Mar 1998 08:42:59 -0800
owner-rfi@contesting.com wrote:

> >From k3lr  Tue Mar  3 03:21:14 1998
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To: <rfi@contesting.com>
> Date: Tue, 03 Mar 1998 00:20:21 -0800
> From: Ed Price <edprice@pacbell.net>
> Reply-To: edprice@pacbell.net
> Organization: ESP Labs
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> To: Wendell Wyly <w5fl@flash.net>
> CC: rfi@contesting.com
> Subject: Re: [RFI] Radio Shack WX200 Weather Station
> References: <004701bd4527$06f989a0$9b0f1ed1@wendellw>
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>
> Wendell Wyly wrote:
> >
> > I have a Radio Shack Weather Station Model WX200.  I have been
> unable to RFI
> > it sufficiently to operate with my HF rig.  Worse problem is on 80
> meters
> > although other bands occassionaly cause the same problem.  An
> indicated
> > windspeed of 125 mph each time you key the transmitter for a few
> seconds.
> >
> > Radio Shack has only suggested filters on the leads to the unit.  I
> used
> > both large clamp on ferrites and split core large ferrites.  Some
> > improvement but it still does not work.  Radio Shack's only other
> suggestion
> > was to move the unit further away from the antenna, which is quite
> > impractical solution for a RACES station.  Also asked to talk to the
> design
> > engineer since I am an electrical engineer, only to learn that the
> design
> > engineer does not work for Radio Shack.  Any suggestions
> appreciated.
> >
> > There are some other issues with the software such as it hangs your
> computer
> > up at midnight, doesn't change to new year properly, and takes 100%
> of
> > kernal processing capacity (when it only updates 10 calculation
> every 5
> > seconds).  I do not think these are RFI issues, however.
> >
> > If anyone has a Weather Station that works well with HF radios,
> please let
> > me know the details.
> >
> > Wendell Wyly     W5FL     w5fl@flash.net
> > (A real 5 located near Weatherford Texas)
>
> Hi Wendell!
>
>         Let me start with a few suggestions that are pretty generic.
> The first
> thing to remember is the SOURCE-PATH-RECEPTOR model. You gotta have
> all
> three for a problem to exist. Varying any of the three will affect the
>
> problem in some way. Try various output powers and bands. Do you still
>
> have interference putting 100 watts into a dummy load?
>
>         Now, I'm not familiar with the RS model in question. Maybe
> your path
> isn't antenna radiation. Or maybe you need to shield the sensor head.
> Maybe tightly twisted data leads will help. Does the data cable
> overshield properly connect to a sensor head shield? Maybe you need to
>
> more severly bandwidth limit the data input cables than a ferrite
> clamp
> is capable of. Try some 5000pf eyelet caps with a small toroid (maybe
> 1mH) in series with the data line(s). (I am pre-supposing the base
> section has some type of shielded box! Maybe we need one?)
>
>         Next, maybe you need to filter the power input to the base
> unit. And
> don't overlook the possibility of coupling onto the computer link
> cable.
>
>         Eliminate some areas, come back with more data on what does
> affect the
> situation. You can kill it, uhhh, eventually.
>
> Ed
> WB6WSN




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