On Jun 4, 4:33*pm, Owen Duffy wrote:

I have thought about this in the past, mainly the prospect of a relay
switched autotuner that reported a calculated load Z based on the found
matching solution, but I concluded that it was not likely to be of
reasonable accuracy over the tuner range.

Probably would be as accurate as any other gear we can afford Owen.
I'm going to suggest that MFJ make that a feature on an auto tuner. I
don't live to far from their headquarters in Starkville, MS. I have a
son going to Mississipi State there and have never been to their
facility. This will make a good topic of conversation.


There is at least one instrument for the
ham market that purports to make such measurements at normal transmitter
power. IIRC, R&S used make a commercial product, but it wouldn't have
come cheap.

I looked on the R&S site. The only thing I found was a "Field Fox"
analyzer selling for $7,599.00. It is the cat's meow, but guess I'll
have to stick with my 259B.


There is at least one other low level antenna analyser that represents
that it is less affected by interference than the '259B.

Which one Owen.

If I were looking for an instrument, I would desire one that could refer
the measurements to a point closer to the antenna (eg the feedpoint)
given the characteristics of the transmission line between the
measurement point and the desired reference plane.

Now that would be a great feature. Input your line type and physical
length and the analyzer does the transform. Lots of programs available
on the web for that, but would be nice to have at your fingertips.

VNAs will peform this calculation, but most low cost VNAs use a broadband
detector and low power, so they are susceptible to interference when used
on antenna systems.

That has become very obvious to me.