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Old May 25th 09, 03:58 AM posted to rec.radio.amateur.antenna
ve2pid ve2pid is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 25
Default ATU: Correct way to specify impedance range

On May 21, 10:28*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


FYI finally got the answer from LDG:
----
It's polar coordinates (as opposed to rectangular).

For example: 200 -j300 in rectangular would have a magnitude of 360 in
polar.

I think we were the first company to ever publish tuning specs for
autotuners
and I happen to choose polar that day, so that's what everyone else
uses now for
autotuners.

It's just an approximate number, but it gives you a rough idea of what
to
expect. If you find that your long wire (for example) has an impedance
of 2500
ohms (either measured or simulated), you can be pretty sure that our
tuner is
not going to tune it.

----
So, I deduct 600 Ohms could mean any impedance A+JB where sqrt
(A^2+b^2)=600. ;-) ........