The technique I use is to set up a signal generator to receiver connection as follows:
Sig gen to short cable to 3 dB pad to 3 dB pad to short coax to receiver I set my reference, then open the junction between the two 3 dB pads, insert my cable, and read my new value. The 3 dB pads minimize the possible problems of signal generator, cable and receiver impedance irregularities. Actually, I use a spectrum analyzer and a sweep generator. That way, I create a continuous sweep of the frequency range. That may be overkill for cables, but this technique also is fine for amplifiers, filters, switches, couplers and attenuators. For cables, I keep my emission (small signal) cables apart from my immunity (high power RF) cables. I buy lowest RF loss cables with low-power ratings (cause they're cheaper), so I don't want to ever pump strong RF in my emission cables. I characterize my emission cables annually. Finally, every month or so, when I get some time to neaten my lab a bit, I try to check each coax cable to be sure the connectors are tight and there is no obvious mechanical damage. This inspection doesn't take very long, since I keep all of my cables coiled and hanging on plastic "garden-hose" hangers (the hangers are cheap and they have a built-in "tray" that hangs the coax with minimum stress). Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis >-----Original Message----- >From: Ken Javor [mailto:ken.ja...@emccompliance.com] >Sent: Friday, November 30, 2001 9:57 AM >To: bolab...@itsqs.com; emc-p...@ieee.org >Subject: Re: Cable calibration > > > >You connect signal source and receiver with a convenient >length of cable and >establish a baseline (-10 dBm out of sig gen yields X dBm at receiver). >Then you connect the cable-under-test (CUT) between the known >cable and the >receiver and measure the additional loss. The purpose of the >original cable >is that usually the sig gen output reading is for indication >only, i.e., the >receiver is the only calibrated item necessary. If you don't have a >calibrated receiver that is OK too, you just need a calibrated >attenuator >with 1 dB resolution really. > >on 11/30/01 7:13 AM, bolab...@itsqs.com at bolab...@itsqs.com wrote: > >> >> I have a few questions for the gurus in the group regarding cable >> calibration for emissions and immunity tests >> 1. what is the preferred step by step procedure for cable >calibration using >> a sig. gen. and spectrum analyzer? >> 2. Is there any standard that outlines the procedure? >> 3.Does the procedure vary depending on the length of cable >and thickness eg. >> coax vs cat. 3,4,5 >> 4. How often should you calibrate the cables? >> >> I would really appreciate comments on this subject. Thanks >> >> Bayode Olabisi ------------------------------------------- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
