On 1/23/19 1:43 PM, Steve Hendrix wrote:
? I don't use any of my VNAs very often, but when I do, they're
indispensable.? I don't know where you're based, but if you're anywhere
near Pittsburgh, you're certainly welcome to use mine if the need
arises...I have a lot of presets and calibration frequency range subsets
for those two ISM bands in particular. ;)
Not all that far...I once made a day trip over there to do my own
investigation of relatives that Children Services was contemplating
placing our foster baby with. I'm about halfway between Akron and
Cleveland, right off I-80 at SR 8.
Wow, this half-typed reply has been sitting there buried under another
window for two weeks. Sorry about that.
But yes, not far at all. You're welcome any time. And I can take you
on a tour of the museum as well, if you're interested.
And don't bother with any of that football rivalry stuff!
Ah, no. Watching grown men chase a ball is not within my spectrum of
pursuits.
I'm curious what model VNAs you have found to be most useful. My test
equipment runs toward the oldie and goodie types, not the
latest-and-greatest whiz-bang gadgets. I like HP gear, except for that
standing for High Priced. My instruments aren't very new, but I know how
to run them and I know how to avoid having them fib to me (mostly).
Looking around my test bench, the only ones I see that I actually bought
new are the TDS220 scope with the full FFT and communications packages,
and an MPJA power supply. Just about everything else is HP (not Agilent
nor Keysight) gear that I've scrounged on eBay etc. I'm a one-man shop,
originally mostly embedded firmware, migrating over the years to digital
hardware, then analog hardware, then RF. I've had to learn as I go and
pick up equipment as I go. My strong suits are 1) Asking stupid
questions 2) Mixing firmware and hardware for an optimum solution, and
3) Being able to work anywhere across the firmware / hardware fence, and
at extremes. Recent projects have ranged from fA to hundreds of A, nV to
KV, DC to GHz, fF to F, etc.
It sounds as though we are cut from the same cloth. ;) My emphasis is
on performance and trustworthiness; no other considerations really get
much attention. I'm not a rich man, but even pricing doesn't bother me
much, as one can always find a deal if one looks in the right place. I
can put pretty much anything in my lab these days...I strive to get the
very best instrument(s) to perform a given function, regardless of age.
This is how I feed myself and my family, so being able to count on my
tools is important to me.
The VNA I use is a well-appointed HP 8510C. I started to "upgrade" it
to an 8753 series machine (because newer is always better, right?), but
the user interface on those is complete ass and they're nowhere near as
flexible as an 8510 system.
I'm still watching for a good buy on a VNA that will go to 3 GHz,
preferably 6 GHz. One got away yesterday when it went from $150 to $2000
in the last 30 seconds of the auction. Ah well, my time will come!
I think I saw that you picked one up. Too bad it's a 75-ohm unit. :-(
But you should be able to just use minimum-loss pads and extend the
reference plane out past them during calibration. I've not done that (I
have no 75-ohm gear) but I see no reason why it wouldn't work.
P.S. Oops! I meant this to be offline, not to the whole group. I thought
there was a way to do a private reply.?!?
There is if you don't bother with the web forum garbage and use it as
a mailing list! ;)
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
Dave McGuire