[ct-user] 7 Mhz RF getting into keyboard.

Alfred J. Frugoli, KE1FO ke1fo@contesting.com
Tue, 6 Aug 1996 20:27:10 -0400

You may want to contact either NCJ or CQ Contest about doing an article on
this, or maybe somebody in the contest community that writes for one of
these putlications can do this.  Either that or someone needs to point me
to a reference for RFI mods to computer equipment.

>X-VE7TCP-Loop-Detector: ct-user "PITMANZ.W9" <PITMANZ@westel900.hu>
>We had the same problem with the keyboards on HG1S/HG73DX. The problem occured
>only when we were operating on 40m. Without any scientific investigation we
>did the following:
>1, Replace the keyboard cable
>Normally these cables are low quality 5wire/mutual-shielded  cables. I went to
>a local HiFi Audio Store and bought a 5wire cable with seperate shielding for
>each wire.
>2, Put small ferrite rings on the wires
>Inside the keyboard we put small ferrite rings on the end of the wires and in
>the PC socket.
>Now there's no RFI in the keyboards.
>I should note that the PCs are connected to a superb grounding system and the
>PC houses are the old "desktop"-style ones. We found them the best, since
>there is enough room to put everything you want into to case and it makes a
>good shielding. Since the hinge which holds the cover is not a good conducter,
>the cover has been connected to the desktop house with thick copper wires (cut
>a piece of RG213 or something similar, remove the shielding and on the edge of
>your desk make it flat. You get a 1/2" wide, 0.1" thick flexible conductor.)
>on both ends.
>If you or anybody still interested I can write about the other modifications I
>did on the monitor,  PC power supply and other accessories to keep the
>spectrum clean.
>Best regards
>Zoli HA1AG
>Ps: The antenna tuners are major sources of RFI. If you have any, check the
>grounding and shielding first.
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Al, KE1FO (ex. KE6BER), ke1fo@contesting.com, ke6ber@tiac.net

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