Hello, Jim,
El 04/07/2011 22:00, Jim Lux escribió:
WHat frequency range do you need?
We have an intermittently dead 8510 at work, but in the course of
trying to get it to work again, I've learned a fair amount about it..
For now, 2.2 and 8.2GHz, but would like something that covers future needs.
1) It does the frequency steps by a technique where it commands the
sweeper to do a sweep, times it, and then takes samples at regular
intervals. As a result, the frequency precision of any given point
isn't all that hot. (compared to today's approach of separately
commanding the source to each point)
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)
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
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 ;) )
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.
In comparison, the little <$1000 units you hook up to a PC give data
that's comparable (at least for the frequency range available.. up to
100 MHz-ish).. You might be able to cobble up some mixers and such to
extend the frequency range.
I guess it kind of depends on what sorts of measurements you want to
make.
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)
Thank you very much for your comments! Best regards,
Javier
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