----- Original Message ----- From: "Jim Brown" <[email protected]> To: <[email protected]> Sent: Friday, July 13, 2012 9:35 PM Subject: Re: Topband: Mother of all ferrite common-mode coaxial chokes
> On 7/13/2012 6:21 PM, ZR wrote: >> ----- Original Message ----- >> From: "Jim Brown" <[email protected]> >> Cc: <[email protected]> >> Sent: Friday, July 13, 2012 4:37 PM >> Subject: Re: Topband: Mother of all ferrite common-mode coaxial chokes >> >> >>> On 7/13/2012 12:09 PM, ZR wrote: >> >> Thats correct at UHF and up but what is the error you have actually >> measured >> at 1.8 MHz? > > The errors involved are NOT limited to UHF -- I've observed serious > errors in the lower HF spectrum (i.e., below 10 MHz). It's why Chuck > thinks the resonance of his chokes are as low as they are -- in reality, > they resonate at a much higher frequency. And the errors are even > greater with higher Q materials like #61. ** Define serious errors and using what for measuring? > >>> Quoting from Wes Hayward on the subject of measuring high impedances: >>> >> >> >> >From a quick glance thru that paper I dont see much benefit of RF I-V >> >below >> about 100MHz. What am I missing here? > > These are not simple issues. It takes far more than a quick glance -- > you need to STUDY this stuff. I've provided some excellent references > that are worthy of the effort. The issue is NOT the FREQUENCY of the > measurement that causes the error, it is the fact that the magnitude of > the impedance differs so much from 50 ohms. Wes is measuring at VHF, but > I'm mostly measuring from 160M up to 10M. ** Ive read all that Agilent and other stuff when published since it was part of the engineering library at work. Since we were involved with 10 to100+ GHz it was more a curiosity than applicable. I just dont see the benefit of so much bother since the 4815A seems to do whats needed and rocket science accuracy isnt required....just add a few more beads if it makes you happy. Carl KM1H > 73, Jim K9YC > > > > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1424 / Virus Database: 2437/5130 - Release Date: 07/13/12 > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
