I used a probe calibrated to 450 MHz. I am going to my local hardware store, they used to carry copper and brass stock tubing, and I am going to try your suggestion. Thank you!
---------- >From: Cortland Richmond <[email protected]> >To: Ken Javor <[email protected]>, ieee pstc list <[email protected]> >Subject: Re: Stumped >Date: Tue, Oct 15, 2002, 3:19 PM > > It looks like you've answered your own earlier question, Ken; yes, you CAN > see a difference between a leaky coax and good coax. I don't know that you > can rely on the usual clamp-on current probe up at 400 MHz, but the > relative difference tells you a good deal. And at 400 Mhz you only need a > few feet for most of the power in shield current -- where the leaks end up > -- to radiate away. You may also have copper losses in the shield -- which > is not designed to carry signal current, remember -- as well as radiation > losses through it. > > However, 20 dB more than very little is not necessarily a lot. You can > measure how much is lost to radiation by repeating your original test, but > this time with a small-diameter - as tight as practical - copper tube > replacing the braid, making an almost perfect shield. The power lost > thorough radiation will no longer be dumped to space, and you should see > that as decreased loss end-to-end. > > Cortland > ------------------------------------------- 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"
