Electronics > Metrology

Is this the proper way to calibrate a new rig expert?

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steele:
Is this the proper way to calibrate a new rig expert? I have an older aa30 and have never tired this route

https://youtu.be/PYi_4-BYKFQ

mendip_discovery:
 :palm: Cor he is a little full of himself.

I would say no. Yes, it does work but its not as good as having a set of connectors made up with an open, short and 50Ω load.

The Fluke already has a spec of 1% + 5 digits so at 50Ω it could be 49.0Ω or 51.0Ω so that could cause the readings to be off its not a good sign.

Mark19960:
 :palm:
No way.

Squeezing the connector with a pair of needle nose pliers to get a short?  :palm:
Keeping in mind that you are performing a calibration to set the measurement plane of the instrument.
That means all three measurements have to be done wherever that is.

You have the open...  it's just open. It's not capped but .. ok. it will work in a pinch.
The short is a pair of needle nose pliers being used to squeeze the connector and scarring it up. But is it a real short?
The load... well its coax running off to who knows where.

So.. where does the measurement plane end up being?
Well... somewhere?

Calibrations don't matter much when you either cannot perform them or abuse the equipment.
That is not how you do things "in the real world" as the video is titled....
 :palm:

Denny Wa:
First thing I would say is, this guy should not have any, "customers".  In the correct users hands, these antenna analyzer (all the brands) are very powerful RF Network Analyzers.  I use one professionally to test RF Matching Units from semiconductor processing tools, but I also have a VNA with known good SLOT (short, open, load, thru) calibration loads to compare to, my SARK-110 gives good results.  Back to the posted question, this guy does not have a clue, knows nothing about transmission line theory, and thinks Mr. Smith (and his chart) are Tik Tok posters.

You can do a very good calibration with home made calibration loads for very little money, or no money.  But not what this guy is doing.  Do search for DIY VNA loads, or buy some from China.  You don't need to spend USD $1000 or much much more.  Then enter your turner schematic into one of the many RF Network simulators and have fun, you will be impressed with how powerful these devices are.  Also, make a 3:1 mismatch load and watch how different lengths of coax cable will walk the measurement point around the smith chart.

mendip_discovery:

--- Quote from: Mark19960 on October 22, 2021, 07:02:17 am --- :palm:
No way.

Squeezing the connector with a pair of needle nose pliers to get a short?  :palm:
Keeping in mind that you are performing a calibration to set the measurement plane of the instrument.
That means all three measurements have to be done wherever that is.

You have the open...  it's just open. It's not capped but .. ok. it will work in a pinch.
The short is a pair of needle nose pliers being used to squeeze the connector and scarring it up. But is it a real short?
The load... well its coax running off to who knows where.

So.. where does the measurement plane end up being?
Well... somewhere?

Calibrations don't matter much when you either cannot perform them or abuse the equipment.
That is not how you do things "in the real world" as the video is titled....
 :palm:

--- End quote ---

I have been asked to calibrate short, open, load connectors before but shied away from it as I did do some YT watching and if I wasn't careful I could end up in muddy waters. I have a plan to get a VNC thing for checking my antennas I have here and I will look at making some loads for it. There are plenty of good YT videos out there but also a lot of rubbish ones, much like advice found on forums. ;-)

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