On 12/23/2012 9:56 AM, Phil Hystad wrote:
But, the KAT500 discovers an L & C match by a search process, I think it is measuring reflected voltage but not quite sure about that.
I believe you're likely correct. That's how the KXAT1 operates. My KXAT1 tunes a lot faster than the KAT500 but then, it only has 3 L's and 3 C's plus choosing one of two configurations. The KAT500 has a lot more.
Can
a vector network analyzer type circuit be used in a tuner to actually measure the complex impedance R + jX values and then use that to compute the required L & C values of the matching circuits (L-network ?). Thus, given an input frequency would it not be possible to instantaneously (almost) determine the match?
I would think that, knowing the complex impedance presented to the output port of the tuner, one could compute the values of L and C and the L-net configuration and just "go there." I can do it on my HP48GX calculator. Measuring the actual complex impedance does not take a full VNA either.
In years past ... that would be *many* years ... I and others experimented with what I'll call "analog autotuners" for lack of a real name. Mine was in the trunk of Dad's car along with the 75m radio. The matching network was an L-net. I used a stepper switch to manually select taps on the inductor controlled from the front seat, and an RF bridge produced a DC voltage proportional to the phase difference between the voltage and current in the short line to the antenna. This voltage drove a DC motor on the capacitor shaft which drove the cap to zero the phase angle. It worked, with some "wrinkles" ... it wasn't real reliable due mainly to my construction skills, and I had to detune the antenna far enough so that the polarity of the DC voltage remained the same over the range of frequencies I wanted to tune, or it got "lost." I know of at least one ham who tried to make it work with motors on both the L and C. I don't recall ever seeing that one actually work.
P.S. Or, am I completely off my rocker.
I think that you and your rocker are still firmly intact. :-)) 73, Fred K6DGW - Northern California Contest Club - CU in the 2013 Cal QSO Party 5-6 Oct 2013 - www.cqp.org ______________________________________________________________ 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
