Hi Don, I still doubt that this is correct.
The L/C values given by the tuner, are the values as seen from the tx side. It is the values that will make the tx happy. It does not say much about the impedance at the rig end of the feeder. In order to change the VSWR on the feeder itself, one has to put the matching network (tuner) between the antenna and the feeder. BTW, the tx is probably not conjugate matched by the tuner. Conjugate matching does not apply to transmitters or power amplifiers. But I realize there is a huge dissension in this area too. ;-) Per-Tore / LA7NO On 31 July 2014 22:42, Don Wilhelm <[email protected]> wrote: > Per-Tore, > > Yes it is correct. He stated that it is the impedance at the rig end of > the feedline. > That will not likely be the feedpoint impedance of the antenna. That > impedance can be found if you do the calculations for the impedance > transformation of the feedline (for which the length of the feedline must > be known). > > 73, > Don W3FPR > > > On 7/31/2014 4:23 PM, Per-Tore Aasestrand wrote: > >> Hi Matt, >> >> Of course you realise that the output impedance of the ATU will be the >>> complex conjugate of the impedance at the rig end of your feedline. >>> >> I wonder if this is correct >> >> IMO, the task of the tuner is to make the tx happy, so it can look into >> the >> load it is designed for. Thus, it will translate the impedance as seen >> from >> the antenna connector into something as close to 50 ohm as possible. The >> tuner will not change anything on the feeder. With or without the tuner, >> the feeder will have the same VSWR. >> >> Per-Tore / LA7NO >> >> >> >> >> On 31 July 2014 22:02, Matt VK2RQ <[email protected]> wrote: >> >> Of course you realise that the output impedance of the ATU will be the >>> complex conjugate of the impedance at the rig end of your feedline. >>> However, if you want to know the impedance of your antenna, you need to >>> realise that the feedline is acting as an impedance transformer, and you >>> need to take into account factors such as length of feedline, frequency >>> of >>> operation characteristic impedance and velocity factor of the feedline, >>> etc.. >>> >>> 73, Matt VK2RQ >>> >>> On 1 Aug 2014, at 1:02 am, TF3KX <[email protected]> wrote: >>>> >>>> Thanks. Yes, I can determine the tuner settings (L/C-values, etc.) and >>>> >>> from >>> >>>> the network equations derive the impedance these settings match into. It >>>> would be neat if the K2 had enough CPU power and memory to carry these >>>> calculations out for me and just display the R+jX. Perhaps a good >>>> project >>>> for a small program or an app... >>>> >>>> 73 - Kristinn, TF3KX >>>> >>>> >>>> >>>> -- >>>> View this message in context: >>>> >>> http://elecraft.365791.n2.nabble.com/Can-I-measure- >>> antenna-impedance-with-K2-tp7591798p7591803.html >>> >>>> Sent from the Elecraft mailing list archive at Nabble.com. >>>> ______________________________________________________________ >>>> Elecraft mailing list >>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>> Help: http://mailman.qth.net/mmfaq.htm >>>> Post: mailto:[email protected] >>>> >>>> This list hosted by: http://www.qsl.net >>>> Please help support this email list: http://www.qsl.net/donate.html >>>> Message delivered to [email protected] >>>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [email protected] >>> >>> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] >> >> > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
