On 7/4/11 1:40 PM, Javier Herrero wrote:
Hello, Jim,
Again for now, no extensive frequency precision, so would be suitable. I
suppose that this is valid with the 8350B sources, but does it operates
in the same way with an 8340 synthesized sweeper, or in that case it
commands the frequency source for each point? This can be an important
point to take into account (again, mostly thinking in future needs)
I think that's determined by the controller, more than the sweeper.
That is, the controller doesn't have the software to send a command to
the sweeper for each point. It sends the commands to set the
start/stop/sweep time, and then has an actual discrete "start" pulse to
start the sweep.
2) The calibration math isn't as slick as you can do today. I suppose
one could get raw data out, and then post process it for any sort of cal.
Good to know :) again for now, more interested in amplitude than phase
measurements... but I prefer an VNA since I think it is a better
investment for future projects
you definitely want phase. Otherwise a regular old sweeper and a
spectrum analyzer would do. But phase implies a synchronous receiver,
which greatly improves the dynamic range, and that's often what you want..
3) It's a big beast. Better than 1/2 rack full of stuff
(display/controller, receivers, test set, sweeper)
I know, I know... have seen several, mostly sitting inside a 18U rack
only for them :). But I prefer to have an external source (for
flexibility reasons)
4)The user interface for the 8510 is fairly easy and convenient,
although distinctly 80s-90s vintage, and the general build quality is
very good, so you get good quality metrology: repeatable, etc.
I have seen that 8510s are used nowadays in lot of places, this is also
a fact that makes me somewhat confident on them. And I feel happy with
these 80s-90s vintage user i/fs (an age-adquired defect, I suspect ;) )
The challenge will be fixing it when it breaks. They've been "out of
support" from Agilent for a few years now, and they're a complex beast.
OTOH, given the level of ad hoc support you can get from groups like
this one, you can probably get enough info.
I think the 8510 was the first real high performance automatic VNA so
there's tons of them out there (even at hundreds of $k each, they save
so much time for the engineers...).
The RF sections, attenuators, detectors, etc. are really nice, I wonder
if it would be worth trying to come up with a retrofit for modern PCs...
Also... I like the building quality of HP in that period (do not like
Agilent nowadays so much... you can call me nostalgic :) ). Also, I
think that the 8510s are more 'repaireable'. I suppose that this is not
the case for a modern Windows-base Agilent PNA.
I think the folks on this list would agree... Those 8663s and such are
probably never to be duplicated.
I think I prefer the big thing ;) Another problem is that I must have it
calibrated by an accredited laboratory, and to get a calibration
certificate for an 8510 is not difficult since most good calibration
laboratories already know it (not an unexpensive certificate... but not
difficult to get). These little units, with external mixers and sources
for the mixer, would be a bit of franken-vna to convince the customers
on the measurement quality (you know... the -hp- logo is related to
quality even for 20-30 year old instruments, and the customer feels more
confident if they see that you use good quality instruments for doing
the qualification - they don't seem to mind too much if they are not the
latest state-of-the-art unit)
Ah, yes... then an 8510 might be what you want.
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