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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: RF Metrology
Date: Sun, 29 Sep 2024 22:08:25 +0200
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On 9/29/24 20:57, John R Walliker wrote:
> On 29/09/2024 19:02, Jeroen Belleman wrote:
>> On 9/29/24 19:14, Cursitor Doom wrote:
>>> Greetings, gentlemen,
>>>
>>> [...] 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.
>>
>> Aren't we getting a teensy bit lazy?
>>
>> Jeroen Belleman
> 
> I have seen transmission (S21) losses of around 1dB at about 1.2GHz
> just from failing to tighten an N connector sufficiently.
> We do need to know the magnitude and frequency of the problem in
> order to give helpful comments!
> John
> 

I collected some TDR traces of various connectors, adapters and
terminators a few years ago: <https://cern.ch/jeroen/connectorTDR>.

There were a few surprises. I was taken aback by the poor results
for H+S BNC and LEMO-00. For BNCs, Radiall is better than H+S, but
for N-connectors, it's the reverse.

After having seen what LEMO-00 hardware did to my signals, I was
pleasantly surprised by the performance of SMC.

SMA was the best I had around, hands down, no surprises there.

Jeroen Belleman