Joel Kolstad wrote:
Thanks for the help, Andy... I muddled through it (it's a little odd the first
time you've normalized your Smith chart to 1800 ohms and the termination is 50
ohms!) and the filters do work as their data sheets say.

I did find that xtal filters can easily drive a network analyzer nuts... even
for looking at a single frequency, I had to significantly increase the
sampling time well above the default to get a stable display. I'm thinking
this is due to the absurdly high Q of the crystals causing a very long
transient response, thereby necessitating a long sampling time to finally
measure the steady state response.

---Joel

Andy writes:

Joel, one more thing comes to mind.

I like to match impedances using a "double Smith chart". On this
chart,
a normal smith chart is in one color while the mirror image is in
another
color.....
It is called an "impedance-admittance" chart.

One can follow the series reactances along one color, and then
the parallel reactances along the other, to get from the starting
point to the ending part....

Once a person is comfortable using this method, it gives a LOT
of gut feel insight to the various combinations of matching networks
you can use.....

I had to design an automated antenna tuner for Texas Instruments
once, for the HF SSB marine system, and I used the double Smith
Chart to figure out what the combinations needed to be, and then
wrote a computer program that would step reactive elements in series
or parallel . The automated system therefore just stepped along the
curves exactly as I had done by hand..... That was about 30 years
ago.

Anyway, the Smith Chart, and various derivative versions, is great
because you can see a much larger 'big picture" rather than just
discrete values at discrete frequencies...... It's a good and very
useful skill to have... among others..

Andy in Eureka, Texas W4OAH