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From: john larkin <JL@gct.com>
Newsgroups: sci.electronics.design
Subject: Re: RF Metrology
Date: Sun, 06 Oct 2024 10:26:20 -0700
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On Sun, 6 Oct 2024 17:46:02 +0200, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:

>On 29-09-2024 19:14, Cursitor Doom wrote:
>> 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?
>> 
>Measurement of good vs bad cables:
>
>https://www.youtube.com/watch?v=AqFDxQjJAdA&t=50s
>

I solved a billion-dollar showstopper last year. Some country started
demanding that some expensive semi fab gear be EMI tested, and our
units failed. After great hassle we traced it to bad ground crimps on
shielded CAT5 cables that our customer bought cheap.