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[TenTec] RE: RFI to power supply speaker

To: <tentec@contesting.com>
Subject: [TenTec] RE: RFI to power supply speaker
From: jimmitch@jetcity.com (Jim Mitchell)
Date: Mon, 13 Oct 1997 17:32:00 -0700
-----Original Message-----
From: Webster D. Williams <kr4wm@sccoast.net>
To: tentec@contesting.com <tentec@contesting.com>
Cc: Bob Hirsch <bobh@p3.net>; John/K4WJ
<bohnovic@worldnet.att.net>; rohre <rohre@arlut.utexas.edu>
To: <tentec@contesting.com>
Date: Monday, October 13, 1997 9:34 AM
Subject: [TenTec] RE: RFI to power supply speaker

>I'd like to thank all who replied, and let you know my progress.
>There was something I failed to mention: I'm running a Radio
Shack DSP
>unit. This is an UNSHIELDED device in a plastic enclosure. I had
>forgotten about that. That was an ommission on my part.
>I've run into problems in the past when trying to ground this
device. It
>seems that it operates with a "floating ground". If you connect
>"ring" (DC ground) of the power input jack to "shack ground",
you get an
>instant blown fuse in the DSP unit!

Unfortunately, while the RS DSP does work, they are an RF horror,
and are <very>
susceptable to VHF - as you've discovered .....

>I think my next step is going to be to re-work my RF ground,
>consists of 5 6-foot ground rods connected with #6 solid wire in
>straight line leading away from my shack. I have that connected
to the
>shack with stripped coax braid, which is about 8 feet long. I've
>all bands, and the RFI seems to be equal across the spectrum, so
>not frequency dependent.

Try connecting with all braid, the object is to achieve a low
<impedance> RF ground,
not necessarily the same thing as a low resistance ground.

Good Luck


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