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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: RF Metrology
Date: Sun, 6 Oct 2024 19:44:23 +0200
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On 10/6/24 19:26, john larkin wrote:
> 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.

I bought a set of phase-matched cables from Taiwanese company
JYEBAO because my usual supplier Huber & Suhner failed to
answer a quote request. I was pleased to find that JYEBAO's
cables were *better* than H+S, and cheaper too.

Jeroen Belleman