On 3/8/20 9:31 PM, Jinxie wrote:
I do actually have the storage normalizer for this VNA. But I have no
idea what it's for or what it does.
Ahh, you do have one! Excellent.
Basically a storage-normalizer provides digital storage, and simple
(but specific) math capability for the VNA, providing a great
improvement in general usability.
First, digital storage. You'll note that you can usually get better
RF performance from the VNA if you slow the trace down, but then you get
a slowly moving dot rather than a quickly-refreshing trace, and it's
much harder to visualize the curve. Digital storage preserves the
waveform on the screen and allows it to be slowly replaced with new data
as the next trace progresses.
Normalization is a much bigger deal. It allows you to subtract one
response curve from another. This is useful in the real world of
imperfect cabling and connectors. Let's say you have two cables
connected to ports 1 and 2 of your VNA, and you've connected an
attenuator between them to measure its response over a frequency range.
What you get isn't only the response of the attenuator, but also of the
cables and connectors. Their contribution to the displayed data can be
very significant, depending on several factors.
The normalizer allows you to, say, connect those cables together in
the middle first, without the attenuator, measure the response of that
cable and the connectors, and store it in memory. Next, you insert the
attenuator, and the normalizer subtracts the previously-stored response
of the cable from the displayed measurement, giving you much closer to
correct results.
More modern VNAs (say from the early 1980s on) do this in a very
different way, and that's a capability that your 8754A lacks, so that's
outside the scope of this discussion. But you can see what the
storage/normalizer unit does and how it would be useful.
Do you have everything required to connect your storage/normalizer to
your 8754A? What model is it?
I don't want to go down the route of a newer instrument. With gear of
this vintage I can keep them alive and fix them up when they go wrong.
I'm right there with you on that. But in the case of VNAs, there's
very real functionality that has been added, real game-changing stuff,
that you may end up wanting. Just keep it in mind for the future. It's
not really like the oscilloscope world where display voltage against
time has been a solved problem for decades, and the main "improvements"
are production cost and profit margin. (except for high-double-digit-GHz
bandwidth that almost nobody actually needs)
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
Dave McGuire