jdm@hodge.UUCP (jdm) (05/18/89)
> | One way of turning a Class A into a Class B is to put conductive paint all > | over the inside of the box; any experience with this ? I have an old H/Z-89A that puts out RFI in bucket-loads. The worst offender on any computer is the keyboard. It dosen't take a HAM operator to realize that the foil grid pattern on the keyboard's PC board acts like an antenna boardcasting RFI right into your face. My solution was adhesive-backed copper foil like they use in making stained glass. It just so happened that there is a stained glass craft shop near me and I found that fairly thick copper foil with adhesive backing can be bought in any size from large sheets to very thin strips. I covered every interior inch of the Z-89's plastic case with copper foil. I then connected all the foil to ground by scraping a corner of the foil, applying flux, and soldering a copper strip between all the foil sheets. A quick check of continuity to verify the connections finished the job. The RFI output was decreased considerably (as demonstrated by a near by TV set). -- jdm@hodge.cts.com [uunet zardoz]!hodge!jdm James D. Murray, Ethnounixologist Hodge Computer Research Corporation 1588 North Batavia Street Orange, California 92667 USA TEL: (714) 998-7750 Ask for James FAX: (714) 921-8038 Wait for the carrier
ritchie@hpldola.HP.COM (Dave Ritchie) (05/20/89)
Another way to shield cases is to use the conductive nickel material
("aquadag", I think) which was first used to coat the insides of television
CRT's. It is conductive and easy to apply to irregular surfaces. (If you've
looked into cases of some computers, it's the gray stuff on the inside of
the case).
Dave Ritchie