On May 21, 7:28*am, ve2pid wrote:
Hi to all,

Just got my new ATU. The specs mentionned:

Tunes 6 to 600 ohms (about 10:1 SWR range). 16 to 150 on 6M (about
3:1)

It sems that this is the standardized (?) way to mention
specifications...

But, since impedances have both a resistive and reactive compoment,
doses it means 6 to 600 Ohms "resistive"?

For example , if Z= 500-J800 ohm, is it 'tunable'? I have a doubt
because the impedance could also mean sqrt(500^2+800^2)=943,4 Ohms..

Thanks de Pierre

It would be good if they plotted the range on something like a Smith
chart. It should be done for different frequencies; it's rare indeed
for a tuner to be able to match the same range of impedances over its
frequency range. Some tuner topologies even have "holes" in their
coverage.

Icing on the cake would be some additional lines on the Smith charts
showing the expected power loss, perhaps as constant-loss contour
lines. Many (most? all?) tuners get pretty lossy at some
adjustments.

As far as I know, none of the ham manufacturers do that. I expect it,
though, for commercial equipment, and we ought to hold the ham
manufacturers' feet to the fire to do something similar.

Cheers,
Tom