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8065Re: [RADIOSHACKDX394] Re: Metal Covers

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  • T. Hills
    Jan 12, 2014
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      My apologies. I didn't expect to run into sock-puppets in a hobby group.

      When I was in college the EE RF Lab had a Faraday cage with one very well filtered and isolated outlet strip. Quite handy for prepping/shielding lab equipment. The WJ receiver with a low noise preamp we built and an 18" whip could pick up the noise in HF from flicking my Bic 10' away.

      Eliminating the noise sources in/around the house has gone a long way to improving reception but I have neighbors on either side with plasma TVs and all manner of switching wall warts and motion sensing lights, etc. Not to mention the 3 MW stations who's night patterns converge in my back yard :P

      Shielding is one of the main reasons I chose to use a junked DX-150 to house my latest hombrew.

      Tim Hills
      Sioux Falls, SD
      On 1/11/2014 12:56 PM, Tom H wrote:

      Thanks for your comments, Tim.

      The challenge to achieving the most effective shielding of the 394 is to completely enclose it with electrostatic and ferro-magnetic material. The chassis or frame is good material but only 3-sided. The plastic lids can be replaced or supplemented by electro-magnetic material as has been done in a variety of ways. If well-connected to the frame, a 5-sided enclosure is the result.

      Unfortunately, that still leaves the front which is basically plastic and the logic pc board. The ground lands of the latter may provide some shielding but it is impossible to close the box with material between the front panel and the frame - too many things penetrate the plane. Likewise, holes for the loudspeaker, ventilation, power cord degrade the shields.

      The most effective shield would be an enclosure around the whole radio, power it from a battery within the enclosure and have an access door (a compromise) to reach the controls. The shielded coax from the antenna would pass through a coaxial feed through connector. Not very appealing operationally.

      Re your first comment, Alfred Santee is an alias for Ernie Rice which might be an alias for...

      Tom, ve3meo

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