>-----Original Message----- >From: John Woodgate [mailto:[email protected]] >Sent: Thursday, October 10, 2002 1:10 AM >To: [email protected] >Subject: Re: EMI suppression for fiber-optic thru-hole ... > > > >I read in !emc-pstc that Doug McKean <[email protected]> >wrote (in ><[email protected]>) about 'EMI suppression >for fiber-optic thru-hole ...' on Wed, 9 Oct 2002: >>Now the cable is of course non-conductive, but is >>there some emi grommet for the gaping hole in such >>a construction that plugs up a large diameter hole >>while at the same time allowing for a small thru-hole? > >I've seen a cheap standard mechanical metal part used for that. It's a >domed top with spring fingers dangling below it (think 'jellyfish'). It >was modified by the user by having a bite taken out of the >edge, using a >simple press tool, allowing the fibre to pass through. Far cheaper than >a conducting grommet and worked well. >-- >Regards, John Woodgate, OOO - Own Opinions Only. >http://www.jmwa.demon.co.uk >Interested in professional sound >reinforcement and distribution? Then go to >http://www.isce.org.uk >PLEASE do NOT copy news posts to me by E-MAIL! John may be talking about (what's called in the USA) a "knock-out plug." These are commonly available in most hardware stores, and come in several sizes to match the conduit holes in metallic wiring boxes. If you make a mistake and knock out too many holes, you can put a knock-out plug in to fill up the unused hole. These plugs are often zinc or nickel plated, and have a series of spring "fingers" that hold the plug very firmly in the hole. They do a pretty good job as an RF plug, as long as they are clean and you make sure the finger tension is strong. To accommodate a fiber cable, you will have to make a small notch at the perimeter to avoid stressing, or even cutting, the cable. If you are doing a production quantity, this will be an operation that needs a special mechanical jig. If it's just a few pieces, you can cut a little radial notch with a hacksaw blade. If you really want to get fanatical about the RF joint, you can try tack soldering a few bonds around the perimeter of the plug (but don't melt your fiber cable). Regards, Ed Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
