On Oct 31, 1:22 am, "David" wrote:
I recently purchased an older model HP8753 Vector network analyzer. It came
with the reflection test set and calibration standards.

I have looked for some time on the net and cannot find any documents that
describe how to make practical measurements.

Initially I want to characterise some passive components (caps etc) and I
also want to be able to measure the unput impedance of an active device.

Can someone please point me in the right direction or maybe explain how I
set up a test. I have seen responses in books showing the impedance of a
capacitor and the self resonant response but when I connect a Cap to the
test port on the reflection test set I can see the correct capacitance curve
on the Smith chart display but when I switch to mag, the line is flat acorss
the band. I cannot tell from the Smith Chart where it is self responant.

Thanks in advance for any help

Regards

David

I gather your 8753 must be an 8753A. The one on my bench (8753E) has
the two-port S parameter test set built in, an integral part of the
instrument, so your comment about a separate test set surprised me at
first. You didn't mention the model number of the test set
(transmission/reflection?? You only mentioned reflection, but the
ones I'm aware of are labeled t/r, I believe...). It's also not clear
just how much info you DO have. A starting point is the Agilent web
site, where you will find several different manuals in PDF format for
your VNA, at least, and perhaps the t/r test set too. Hint: enter
8753A, not just 8753, in the search box, and select manuals for the
type of info. I have an 8754 and t/r test set at home, and the
photocopied manual I have for it does talk about how to set things up
and make basic measurements. -- I just downloaded the 8753A operating
and programming manual, and I have to say, it really doesn't cover
making basic measurements very well. Try the 8753E User's Guide (doc.
# 08753-90479) for some better info on actual measurements--or poke
around a little and you can probably find even better ap notes and
manuals for what you want to do. There's a lot there, not always easy
to find.

I believe you should also be able to find ap notes on the Agilent web
site about making various kinds of measurements. Search the
literature for the 8753A first, but don't be shy about searching for
ap notes on VNAs in general. I dare say you can even find some things
on the Rohde and Schwarz or Anritsu or similar web sites, if you don't
get overwhelmed by everything on the Agilent site. By the way, it's
not always easy to tell from a Smith chart where resonance is,
especially if it's not very high Q. Obviously, resonance may not be
very near 50 ohms, and at extreme edges of the Smith chart, small
distances can represent big percentage changes in impedance. The self-
resonance in a capacitor may take the impedance down to 0.01 ohms or
less, and it's very hard to resolve the difference between that and,
say, 1 ohm on a VNA display. It may be more useful to look at a plot
of phase versus frequency, and look for places where the phase goes
through a large change rapidly.

Cheers,
Tom