I really don't know the answer but maybe you could use a spectrum analyzer
and a noise source. This will not tell you the impedance but you should be
able to improve your circuit by trial and error. It may also show you any
resonances in band, and noise peaks. A dense 'fence rail' signal may
replace the noise generator and make the noise floor easier to see on the
specan when you tweak the circuit.

Peter

On Tue, 9 Jul 2002, Brendan Moran wrote:

>Perhaps I should refer to what I am actually trying to do here.  I have this
>same preamp.  The input is really not much of a question since the source
>for it is a >5k + j0 ohm coil.  It's tough to match, but I have something
>that works.  Once again, magnetic components for this particular project are
>a nono.  It also needs to be small in size.  This eliminates the use of
>large value inductors, and large trimmer caps.  It's the output that's
>giving me grief.  I need to get a measurement of the current impedance
>before I can do much to fix it, since the only specs I have for the active
>component are for a long way outside of my freq. range.
>
>The test equipment I have available is as follows:
>1xHP4395A network analyser
>1xHP54645A DSO
>1xHP43961A Impedance test set
>1x Nice function generator.
>1x Not so nice function generator.
>
>1x Hybrid power splitter
>
>With that, and something I can build easily, how can I measure s-parameters
>or impedances accurately?
>
>--Brendan
>
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