I'm running tests today with the 25 ohm load connected to the K3/LP-100 with varying lengths of RG-142B/U coaxial cable, in 24 inch increments out to 120 or 144 inches. The result should be a constant SWR, neglecting the padding effect of coaxial cable loss, but with the impedance varying along the constant SWR circle if we think in Smith chart terms.
I will also measure the R+jX of the load under the same conditions, with both the LP-100 and a VNA. I may have the data analyzed this evening, but more likely tomorrow. Also added a note confirming that my K3 has the KAT3 tuner, set to BYPASS for the tests. Jack N8LP wrote: > That's a good question, Paul. I have a medium power, 150 ohm load laying > around that I made up a couple years ago for testing purposes. I just > checked it with my VNA and it has an SWR of 2.92, pure resistive. I did a > quick test with the K3 at 25W, and it measured between 2.4 and 2.7 depending > on band. That's about the same percentage error as the 25 ohm load, but it's > impossible to know if the error is in the same direction. I would think that > you could calculate the direction using the "tuned" L-network values of a > KAT3, but I don't have one installed. > > Larry N8LP > > > > P.B. Christensen wrote: > >>> consistently lower than Jack's, ie. 1.6 on most bands with a 2.0 load. >>> Not >>> a >>> big deal, but as long as you're in there tweaking the code, can you >>> verify >>> that it works with non-KAT3 radios as well? >>> >> I'm curious -- are those who see a smaller indicated VSWR reading on the >> K3 >> meter with a 25-ohm load seeing the same discrepancy with a 100-ohm load? >> This may partially explain why some owners are seeing varying results >> under >> a 2:1 VSWR since that ratio can be comprised of those two resistance loads >> or an infinite set of resistive + reactive conditions -- any of which can >> form a load impedance of 25 or 100 ohms. >> >> Paul, W9AC >> >> ______________________________________________________________ >> 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 >> >> >> > > ______________________________________________________________ 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
