"John S" wrote in message ...

On 8/9/2015 12:23 PM, Wayne wrote:
I was looking at a MFJ remote antenna tuner, and it is specified as
being able to match 12 to 1600 ohms.

What does that mean? At 12 ohms the SWR would be about 4.2:1 and at
1600 ohms a SWR of about 32:1.

The 12 to 1600 ohms is the RANGE that the tuner is capable of matching.
Forget SWR because it has no meaning at this point.

That's a bit of what I was getting at. I have another tuner rated for 4:1
SWR, and I assume that means it will match all the way around the 4 circle.

I don't know what to do with a 12 to 1600 ohm spec.



If one started from 1600 ohms around a Smith chart, the circle would
intersect at the other side at about 0.64 ohms.

You are not analyzing this correctly. If you are really comfortable with a
Smith chart, put a capacitor across the 1600 ohms and then put an inductor
in series with the results. By adjusting the values, you can achieve a 50
ohm output.

Likewise starting at 12 ohms and going halfway around the chart would
end up at 210 ohms, not 1600.

This is similar to the above, but now you want a series impedance and a
shunt impedance following it.

I was just showing that the 12 and 1600 are not on the same circle.



How does one use the specs if the antenna to be matched has a complex
impedance? Look at the internal tuner component ranges?

That is a good question. Do you want to buy the tuner and tear it down to
explore the component ranges, or would it be better to ask the designers?
You should ask them to define the type (complex impedance) of the load to
which their specs apply.

I suspect the designers have a gag order from the marketing guys.