On "missing parts": some opens(mostly early, and I'm specifically
thinking of APC 3.5 connectors) consisted of a body having no center
conductor attached, plus an insertable center conductor on a plastic
rod. Without the inserted center conductor, the characteristics of the
"open" would not match the values assumed in the calibration calculations.
On "open / short combo": Neither standard has much length, so the two
can easily be packaged into one assembly, strictly for convenience (less
likely to be misplaced because it is larger). There's no coupling
whatsoever between the two ends.
Dave
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On 12/23/2012 7:11 AM, Peter Bunge wrote:
Merry Christmas all!
My friends and I have been comparing what we see from the S Parameter
Test Set on the two ports. These tests are with the VNA uncalibrated
and with proper opens or shorts (even from APC7 cal kits).
Typically we get completely different shaped curves ranging from -35
to -55 dB.
I get very similar results using the same S Parameter Test Set on an
HP8753B and an HP8753C so the curve shape is caused by the test set
not the VNA.
Typically we see one port 10 dB better and flatter than the other.
Any comments?
p.s. the cal kit discussion was very informative and timely. I still
don't understand the comment (that was later corrected) about the open
usually missing a part. My friend's Type N cal kit does not have extra
parts for the open. Also I have seen an open/short combo advertised
and wonder if this comes apart to use the open??? I have not used one
and find the concept of one end a short (OK) and the other an open
(how?) confusing.
--
Clear Stream Technologies
