--- In [email protected], "Jamey Wright" <[EMAIL PROTECTED]>
wrote:
"...I'm still learning how to use this HP8920. ..."
______________________________________________________
Let's assume you are doing this test as a swept test, i.e. using the
tracking generator. With the 8920 you can set the generator to a
fixed frequency and observe it on the spectrum analyzer - OR - you can
set it to be a tracking generator to display device response
characteristic as an amplitude vs. frequency display - which would be
the preferred test for a cavity.
Once you have the generator and anlyzer set up for the correct center
frequency and span of the device being tested - the cavity in this
case - then you hook the cables together with a through adapter.
Don't worry about a couple of dB difference. There is cable loss to
consider as well as differences in amplitude accuracy between the
generator output and the analyzer.
There is a procedure to deal with this called "Normalization" On your
spectrum analyzer screen at the left edge highlight "Controls", click
the knob, then select "Auxiliary"
Now go to the right side of the screen and stop on "Save B" click
that. Now you have stored a reference data set. Move down to "A Only
/ A-B" and click so that "A-B" is underlined. The display changes to
a flat line with no amplitude variations vs. frequency. The word
"Normalized" will appear on the screen.
Now your marker will display the actual insertion loss at every
frequency relative to this zero loss trace. Hook the cables to your
cavity and you should see a the actual cavity loss which should be
between 0.5dB and 1.5 dB depending on the cavity loop setting. [Even
if not field adjustable]
If you don't have the user manual and applications handbook for the
8920, you can go to the Agilent site and download them.
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