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From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design
Subject: Re: RF Metrology
Date: Sun, 29 Sep 2024 17:39:38 -0000 (UTC)
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Cursitor Doom <cd@notformail.com> 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?
> 
> Your pal,
> 
> CD.
> 

Hard to tell. How big are the whoopdedoos, and roughly where?

Posting a screenshot would help. 

Cheers 

Phil Hobbs 

-- 
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics