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Measuring complex output impedance

L

Lord Snooty

Jan 1, 1970
0
Does anyone have a nice simple technique for measuring both parameters of the
complex output impedance of a signal source, like an amplifier? I'm interested
in the MHz domain if that's relevant. I would want to model the source as
having a voltage source connected in series with one real impedance R and one
imaginary reactance jX.

Andrew
 
E

Externet

Jan 1, 1970
0
Hi Andrew.
I do not know if you are referring to the output circuitry of a final
amplifier or to the load conncted at its output.
Complex measurements are not to be measured with simple intruments,
but there is an instrument that behaves well, it really shines light
on unknown parameters for RF antennas. I have the MFJ249 and behaves
great.

http://www.mfjenterprises.com/products.php?catid=49

Search for reports on the MFJ259B; it may suit your expectations.
Miguel
 
A

Anthony Fremont

Jan 1, 1970
0
Lord Snooty said:
Does anyone have a nice simple technique for measuring both parameters of the
complex output impedance of a signal source, like an amplifier? I'm interested
in the MHz domain if that's relevant. I would want to model the source as
having a voltage source connected in series with one real impedance R and one
imaginary reactance jX.

I didn't know that any such thing even existed. I had always thought
that the _output_ impedance of a circuit was always purely resistive and
that any reactance that is created is due to trying to feed that into
another device with a different characteristic impedance.
 
E

Externet

Jan 1, 1970
0
Hi.
I would say if the output specifications on a RF amplifier is "output
impedance = 50 ohms"; it is not purely resistive, or it would be
specified as "output resistance = 50 Ohms"

Miguel
 
K

Karl Uppiano

Jan 1, 1970
0
Externet said:
Hi.
I would say if the output specifications on a RF amplifier is "output
impedance = 50 ohms"; it is not purely resistive, or it would be
specified as "output resistance = 50 Ohms"

I've seen it written "output impedance = 50 + j0" to indicate pure
resistance.
 
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