I have an auto tuner whose specs for the output a
"10 to 250 ohms"
Does that have any useful information other than perhaps the R part of R+j.

I have an auto tuner whose specs for the output a
"10 to 250 ohms"

Does that have any useful information other than perhaps the R part of R+j.

That's not particularly comprehensive information, since it doesn't
say whether it's R, or |Z| that it's describing, and doesn't say
what frequency range this spec might apply to. It's likely that any
auto-tuner (or any manual one!) will have different matching ranges on
different bands.

This spec *might* mean "This tuner will successfully match most loads
within a 5:1 SWR range, on most of its bands, most of the time."

Or, it might mean much less than that.

You could ask the manufacturer for a full specification on the actual
impedances that can be matched on various bands (e.g. a set of Smith
charts). They may or may not be able to provide them.

If you know what the switchable reactances inside the tuner are, and
what the switching topology is (most likely a bidirectional "L" but it
might not be) then you could calculate and plot the outer envelope of
the matching range for any given frequency. The math isn't too
terrible.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Wayne wrote:
I have an auto tuner whose specs for the output a
"10 to 250 ohms"
Does that have any useful information other than perhaps the R part of R+j.

Not really as it could mean magnitude |R+j| or just R.



--
Jim Pennino

Remove .spam.sux to reply.

"Wayne" wrote in
:

I have an auto tuner whose specs for the output a
"10 to 250 ohms"
Does that have any useful information other than perhaps the R part of
R+j.


It shows that the author of the specs doesn't understand impedance which
is two dimensional (real and imaginary part), and he is appealing to
those hams (probably the majority) who think that the magnitude of Z
(which is a scalar quantity like they have used) will win the sale.

If we read it litterally, they have given they have writen impedances
with a real part and zero for the imaginary part. The equivalent VSWR
(50) is 5:1 (funny that). It is not a very wide range tuner for those
purely resistive loads.

That said, the information doesn't help much in selecting the tuner
because you will almost always use it with a load where X is not only
not zero, but quite likely much greater than the R component.

It is BS technospeak for a dumbed down pseudo tecnical buyer.

Owen

"Owen Duffy" wrote in message
...
"Wayne" wrote in
:

I have an auto tuner whose specs for the output a
"10 to 250 ohms"
Does that have any useful information other than perhaps the R part of
R+j.


It shows that the author of the specs doesn't understand impedance which
is two dimensional (real and imaginary part), and he is appealing to
those hams (probably the majority) who think that the magnitude of Z
(which is a scalar quantity like they have used) will win the sale.

If we read it litterally, they have given they have writen impedances
with a real part and zero for the imaginary part. The equivalent VSWR
(50) is 5:1 (funny that). It is not a very wide range tuner for those
purely resistive loads.

That said, the information doesn't help much in selecting the tuner
because you will almost always use it with a load where X is not only
not zero, but quite likely much greater than the R component.

It is BS technospeak for a dumbed down pseudo tecnical buyer.

Owen
-
Thanks to all the responders. I assumed that the spec was to indicate a
general ability to match 5:1, but as Owen said, a dumbed down spec.

Anyway, it is an older Yaesu tuner with a lot of flexibility. I've used it
for years, but am currently considering some different antennas.