[Elecraft] The next generation KAT500

[David Woolley]

That basically requires measuring I and Q components from the reflected 
power coupler, rather than just magnitude.  That, in turn, means 
deriving a reasonably accurate quadrature copy of the main transmit 
signal.  I suspect one of the factors here may be that the tuner has a 
wider matching range than the dynamic range of the reflected power sensor.

However, even with the existing hardware, if you are in the dynamic 
range of the reflected power coupler, you can work out which constant 
SWR circle you are on on the Smith chart, and I suspect that, if you 
probed with carefully chosen partial corrections you could probably find 
two solutions with one more measurement, and remove the ambiguity with 
the third, even using the existing hardware.  The third could probably 
be based on one of the two solutions.

I'd still suggest the biggest problem is the dynamic range of the 
reverse coupler, as, once you have an in range SWR, you can use a 
minimum finding algorithm to home in.

Incidentally, if you do need to do a brute force search, using a Gray 
code progression will be kinder on the relays than linear sweeps.

Some of this may actually already be being done.
-- 
David Woolley


On 09/07/2021 00:34, Andy Durbin wrote:
> The next generation KAT500 should measure the complex load impedance, including the sign of X, compute the L and C required to match, and plug in those values as the initial tuning solution.  Why wouldn't this approach be better than flailing around in the dark like most auto tuners seem to do?
> 
> I doubt this will ever happen but the idea of combining the KAT500, LP-100A, and an Arduino controller to implement this "smart" tuner keeps banging around in my head.   Maybe one day I'll give it a try.
> 
> 73,
> Andy, k3wyc
> 
> 
>