Yes, that is true - the laws of reciprocity apply, and a conjugate match is indicated here - but OTOH, the MFJ259 does not display the sign of the reactance directly, one must check above and below the frequency of interest to determine the sign - some other analyzers do display the sign of the reactance..
73, Don W3FPR > -----Original Message----- > > If the L-net brings the system to resonance (X=0) then whatever reactance > the L-net introduces must be equal to the reactance present at the antenna > but opposite in sign! > > For example, if the antenna shows j-500 ohms, the L-net must show j+500 > ohms. So if you want to know what the antenna shows based on measuring the > L-net, you must reverse the sign! > > Ron AC7AC > > -----Original Message----- > > Don Wilhelm wrote: > > Jack, > > > > Yes, connecting a measureing instrument directly to an antenna can be > > troublesome if there are strong broadcast stations in the area or > > other sources of signals that can fool the instrument. > > > > Zack Lau addressed that situation in a Technical Correspondence > > article in QST a while ago - his answer was to measure the antenna > > indirectly with an L network - the L network provides selectivity - > > adjust the L network to provide a 50 ohm match, then remove it from > > the antenna, terminate what was the measurement side with 50 ohms and > > measure the side previously connected to the antenna. > > > > Sounds like a sane way to approach it to me. > > I'm not sure of the reasoning, but he also said that if you do this, you > need to reverse the sign of the reactance that you get when you measure > the network. > -- > 73, > Vic, K2VCO > Fresno CA > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 268.18.11/721 - Release Date: 3/13/2007 4:51 PM _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
