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From: Jan Panteltje <alien@comet.invalid>
Newsgroups: sci.electronics.design
Subject: Re: RF Metrology
Date: Mon, 30 Sep 2024 05:40:39 GMT
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On a sunny day (Sun, 29 Sep 2024 18:14:53 +0100) it happened Cursitor Doom
<cd@notformail.com> wrote in <mu1jfjtd6521pp9nb0kubcorkkkdh20gu3@4ax.com>:

>Greetings, gentlemen,
>
>I bought one of those TinySA Ultras recently and have spent some time
>testing it today. I have to say it's amazing what they've done for the
>price. I mean, truly amazing. I do have two other 'proper' lab-grade
>RF spectrum analyzers, but I think I'm going to be mostly using the
>TinySA in future as it's just *so* convenient and doesn't weigh a ton.
>Anyway, to get back to the point of this post, having checked out the
>TSA and establishing I didn't buy one of the fake versions that are
>out there, I turned my attention to my mid-level RF SA, an HP who's
>model number escapes me (not the 8566B I've posted here about before
>which is now fully working, but a newer model that's about 1/3 as
>heavy. I say I can't recall the model number but it's not relevant to
>this question anyway. "So what is the fucking question, CD??" I hear
>you not unreasonably cry. Well, it's this:
>When I'm feeding an RF signal into the SA, I'm seeing differing
>amplitudes at different frequencies. So I've programmed in a sweep
>from 10Mhz to 5.4Ghz at -49dBm using my Aeroflex RF signal generator
>and I'm seeing the displayed amplitude vary as it sweeps through the
>range. But this only happens when I'm using a cheap, Chinese N-type to
>SMA adaptor at the signal generator output. Would I be right to
>suspect some imperfection in the manufacturing of the adaptor could
>cause such an effect? I do have a VNA I could characterize the adaptor
>with but it's a bit of an effort to do. It would seem like the SA is
>showing the adaptor's shortcomings in the frequency domain. But is
>that a feasible hypothesis?

I duuno, do not have that thing,
but reflections in cable + connector could create dips and mountains?
That is quite a sweep width!