Jeffrey Angus wrote in news:j64hp4$i7g$1@dont-
email.me:

The Icom tuners are specified at 16.7 to 150 ohms.
The LDG Z11 Pro II is specified as 2-1000 ohms.
Oddly enough, the MFJ Versa Tuner has no specified range.

Impedance is not a simple scalar quantity as expressed above. The
'specification' is incomplete, you would need to ask the sellers what
they meant.

If for example, they mean the R component only, do they imply that X
must be zero, or that X can be any value?

If they mean the magnitude, do they imply that any angle of impedance is
acceptable?

Also missing is any bounds on efficiency.

I have heard from time to time on air, OMs boast that their tuner is so
good, they have matched it up with no antenna plugged in. Obviously,
efficiency is zero in that case. A tuner with lower internal losses
might not achieve the same feat.

Owen