Kirkby calibration kit alternatives?

[hendorog]

OK I found it at work today. I had to walk 1km into a horizontal blizzard to get it as it was being used at another company site

It's a 3.5mm F-F connector but not the same grade as the 3.5mm connectors in a typical Agilent cal kit as it uses expanding female contacts rather than the delicate solid centre (with inner petals) as per an Agilent cal kit. So it might not be that much better than an SMA F-F connector, especially as this one is very old and probably quite worn. But I've cleaned it and I'll try it later today. It's really cold and snowy here in the UK and we've been sent home from work early today and told that we don't have to go back until Monday 

I'll have an initial look at this connector once my VNA has warmed up.

Now that is dedication!

[G0HZU]

It's really cold here because of the gusty wind chill factor and it's hard to keep the house warm. However, I've measured the 3.5mm F-F bullet and the files are below. Note that the room is not that warm even with the test gear on so I don't know if the VNA and Ecal will be stable and OK. Plus this type of measurement really should be done in a proper metrology lab and not with my gear in a spare room in a house.

But here are the results for the 3.5mm F-F left open and with the shorting end cap fitted. The results are fairly good but maybe not as good as I'd expected. I'm off to sit by the fire... the strong winds are sucking the heat out of the house like blowing cold air on a heatsink!

[TheSteve]

My very budget Kirkby kit - I added the USB drive, male and female through's and Pelican case.

[hendorog]

My very budget Kirkby kit - I added the USB drive and Pelican case. I will be buying a good quality female - female and a male to male.

Nice one 

I didn't go for the case or the usb stick. I did get the attenuator and the thru's though.

Mine is still some way away though. I really should use the time to build a case

[TheSteve]

My very budget Kirkby kit - I added the USB drive and Pelican case. I will be buying a good quality female - female and a male to male.

Nice one 

I didn't go for the case or the usb stick. I did get the attenuator and the thru's though.

Mine is still some way away though. I really should use the time to build a case

When I say I added the USB drive and Pelican case I was meaning I added it myself. I already had an extra Pelican 1020 sitting here, same as Dave uses.

[Mechatrommer]

When I say I added the USB drive and Pelican case I was meaning I added it myself. I already had an extra Pelican 1020 sitting here, same as Dave uses.

did the cal kit comes with calibration data? if not, how are you going to calibrate it?

[TheSteve]

When I say I added the USB drive and Pelican case I was meaning I added it myself. I already had an extra Pelican 1020 sitting here, same as Dave uses.

did the cal kit comes with calibration data? if not, how are you going to calibrate it?

Dr Kirkby is emailing me the file for my specific kit to load into my FieldFox.

[TheSteve]

Here is a shot of a Mini Circuits 10 dB 0-6 GHz attenuator. Note the scale is 0.2 dB per division. I really need some phase stable cables!

edit - added the 20 dB one as well.

[hendorog]

When I say I added the USB drive and Pelican case I was meaning I added it myself. I already had an extra Pelican 1020 sitting here, same as Dave uses.

did the cal kit comes with calibration data? if not, how are you going to calibrate it?

Dr Kirkby is emailing me the file for my specific kit to load into my FieldFox.

When you get the s1p files, can you post them please? I would like to compare them with mine when it arrives.

Also, out of interest which type of through calibration did you use for the attenuator pics?

(1000th post whoop whoop!)

[TheSteve]

When I say I added the USB drive and Pelican case I was meaning I added it myself. I already had an extra Pelican 1020 sitting here, same as Dave uses.

did the cal kit comes with calibration data? if not, how are you going to calibrate it?

Dr Kirkby is emailing me the file for my specific kit to load into my FieldFox.

When you get the s1p files, can you post them please? I would like to compare them with mine when it arrives.

Also, out of interest which type of through calibration did you use for the attenuator pics?

(1000th post whoop whoop!)

Simply normalized the system.

[G0HZU]

Try clamping the cable ends so they can't move during the calibration.
Here's a 6dB attenuator measured using the crappiest SMA cables I have here. These are used/salvaged cables that cost less than £1 each on ebay and they are old but made with decent quality SMA elbow connectors. But the cable is regular skinny low cost cable.

See below for the attenuator response to 6GHz and how feeble these old cables are. But I still got a good result with a bit of care wrt not moving the cables during the full 2 port SOLT calibration.

[hendorog]

...during the full 2 port SOLT calibration...

...Simply normalized the system...

I think the difference is ^^^

[G0HZU]

The poor plots were blamed on poor phase stability so I assumed some form of SOLT calibration had been done. What's the point of posting up the attenuator plot if it wasn't made with the Kirkby cal kit? I'm lost...

I also don't see the point of posting up a plot to 6GHz using poor cables and a normalisation. The mismatch uncertainty during the through cal ought to be the main problem, not phase stability. Maybe try it again using attenuators at the cable ends during the thru cal. This will improve the port match.

[TheSteve]

The poor plots were blamed on poor phase stability so I assumed some form of SOLT calibration had been done. What's the point of posting up the attenuator plot if it wasn't made with the Kirkby cal kit? I'm lost...

I also don't see the point of posting up a plot to 6GHz using poor cables and a normalisation. The mismatch uncertainty during the through cal ought to be the main problem, not phase stability. Maybe try it again using attenuators at the cable ends during the thru cal. This will improve the port match.

It is fair you are lost. The post was largely irrelevant, just got caught up playing with my toys, sorry guys.
As far as a cal goes for S21 the only cal option I have is to normalize. The FF I have does not do S12/S22 nor phase with S21.
I can do the full OSL for S11 of course.

With respect to the attenuation plots it is quite easy for me to shift the plots around by moving the cable, I did switch to another which isn't as sensitive but it is still easy to see changes.

edit - G0HZU - the plot you made looks great. Do you know what(if any) kind of averaging or smoothing your analyzer is doing? I can easily make my plots look significantly better with just a little bit of smoothing added in firmware.
Added an example showing S21 and S11(well within the spec of the Mini Circuits attenuator), OSL cal for S11, normalize for S21, smoothing turned on).

[hendorog]

The poor plots were blamed on poor phase stability so I assumed some form of SOLT calibration had been done. What's the point of posting up the attenuator plot if it wasn't made with the Kirkby cal kit? I'm lost...

I also don't see the point of posting up a plot to 6GHz using poor cables and a normalisation. The mismatch uncertainty during the through cal ought to be the main problem, not phase stability. Maybe try it again using attenuators at the cable ends during the thru cal. This will improve the port match.

It is fair you are lost. The post was largely irrelevant, just got caught up playing with my toys, sorry guys.
As far as a cal goes for S21 the only cal option I have is to normalize. The FF I have does not do S12/S22 nor phase with S21.
I can do the full OSL for S11 of course.

With respect to the attenuation plots it is quite easy for me to shift the plots around by moving the cable, I did switch to another which isn't as sensitive but it is still easy to see changes.

If you can get all of the data out of your FF then you could have a go at using scikit-rf for the 'one path 2 port' cal.

I will be doing the same when my cal kit arrives and I'm happy to give it a go as a test run if you post all of the files. I don't have a test set, am just using a coupler.

[G0HZU]

edit - G0HZU - the plot you made looks great. Do you know what(if any) kind of averaging or smoothing your analyzer is doing?

RBW is 1kHz and averaging and smoothing both set to off.

[mgberry]

Great thread on the Kirkby kit. I thought I would throw in my experience as well. I purchased one his kits awhile back and did some measurements using my 85052b and N5221A. My observations were that for a low cost kit it performed pretty well below 3Ghz. I found some challenges above 3Ghz that were basically what you guys have observed. The two things that stood out were inductance issue and connector repeatability. Overall I thought it was a reasonable buy for a low cost kit....of course this is prior to the price hike.

Matt


...Would be glad to make some measurement for anyone that needs additional data points of the kit.

[G0HZU]

Hi Matt
Could you use both the male and female parts of the Kirkby kit to do a 2 port cal for an insertable device? i.e. measure something like an inline SMA 6dB or 10dB attenuator up to 6 or 7GHz?
Then maybe repeat using a different set of SMA test cables to see if the results are repeatable across different mating SMA connectors. You may have done this already and it would be interesting to know what results you got.

I'm not convinced that an SMA cal kit will give repeatable results up in the 3-7GHz region when mated with various makes of SMA cable because of the undefined air gap between the solid dielectrics once the connectors are mated. I think it will be fine to about 3GHz and it already looks like you have reached similar conclusions.

[TheSteve]

Just as a quick followup here is what I have been able to achieve using the Kirkby out of spec SMA cal kit(good to 3 GHz, not 7 GHz) with my N9912A FieldFox handheld analyzer.
Port 1 OSL performed, then normalized to port 2.
Mini Circuits VAT10+ 10dB attenuator.
First capture with 5% smoothing, no averaging.
Second capture no smoothing, no averaging.

edit - added the same captures with VAT20 20 dB and VAT30+ 30 dB attenuators, I only have one of each to measure.

[rfspezi]

I could need some advice on what i am doing wrong with my Kirkby cal-kit.
(Please appologise stupid questions, since VNA measurements are totally new to me )

My setup consists of:
-) HP 8753E VNA (6 GHz)
-) Kirkby 85033 SMA calkit
-) 50 cm RG316D koax

I followed the instructions on the Kirkby 8753 page here: http://www.kirkbymicrowave.co.uk/support/VNAs/HP-Agilent-Keysight/8753/

On the floppy disk there are 3 files (SMA, SMA_M_M, SMA_F_F).
I selected "SMA" and loaded it with "RECALL STATE".
Is that the correct file to choose?

After that, the frequency range is automatically changed to 300 kHz ... 3 GHz.
Shouldn't it be set to the full range of 30 kHz - 6 GHz of my VNA?

Next, i start a "S11 1-Port" calibration.
When selecting "OPENS", a new menue appears and asks me for "OPEN (M)" or "OPEN (F)".
Since i am using the female-open, i guess selecting "OPEN (F)" is correct here?
The same applies to the SHORT.
Just the "LOAD" does not open a sub-menue for (F) or (M).

Ok, so after i finalize the calibration by pressing "DONE 1-PORT CAL", i set the VAN to Smith-chart to verify if calibration is correct.
I do this by attaching the SHORT again and check if the Smith-chart gives me a point at the short-position.
However, i don't get a dot at the short position but a line reaching from short to almost infinit on the upper, outer pure inductor circle.
Similar, just mirrored is displayed when the OPEN reference is connected.

For compensation, i applied a port extension of 58.14 ps and get the expected results (dots) with all 3 calibration standards.

I thought that with the complete calibration data on the floppy disk, there would be no need for manual port extension entry?
Or maybe i am doing something completely wrong here?

Thanks 

P.S.:
Another thing that irritates me is that the 50 Ohm references are 49,5 and 51,1 Ohm instead of "50,0".
I would expect to get better quality references for that price?

[orin]

Next, i start a "S11 1-Port" calibration.
When selecting "OPENS", a new menue appears and asks me for "OPEN (M)" or "OPEN (F)".
Since i am using the female-open, i guess selecting "OPEN (F)" is correct here?

Not usually for HP VNAs.

The (M) means a male test port and (F) a female test port.  So if you are using a female open, you should select OPEN (M) and if using a male open, select OPEN (F).

(Later Agilent changed the convention to indicate the sex of the standard and replaced the parentheses with hyphens so OPEN -F- would indicate a female open and so on.)

This information is on Dr Kirkby's web site, but I could only find it under the old NCV032B kit information here:

http://www.kirkbymicrowave.co.uk/support/Kits/NCV032B/HP/

[G0HZU]

Ok, so after i finalize the calibration by pressing "DONE 1-PORT CAL", i set the VAN to Smith-chart to verify if calibration is correct.
I do this by attaching the SHORT again and check if the Smith-chart gives me a point at the short-position.
However, i don't get a dot at the short position but a line reaching from short to almost infinit on the upper, outer pure inductor circle.
Similar, just mirrored is displayed when the OPEN reference is connected.

For compensation, i applied a port extension of 58.14 ps and get the expected results (dots) with all 3 calibration standards.

Don't forget that your cal kit SHORT and OPEN is at the far end of either a male-male SMA adaptor or a female SMA adaptor. The typical delay in the F-F adaptor is about 42ps and the M-M is probably about 58ps.

So the moment you put your cal kit OPEN back on the VNA after a calibration the open end of your OPEN will be either 42ps or 58ps away from your reference plane. So the smith chart on the VNA will show a 0-6GHz line going maybe halfway around the smith chart. It's effectively measuring the SMA F-F barrel.

My guess is that you have tried to do a 1 port calibration and told the VNA the wrong gender for the cal kit. So the 42ps and 58ps are muddled. Try again for the 42ps female OPEN (and don't forget the VNA refers to this as OPEN (M) ) and it might look like this:

[G0HZU]

If you put the female SHORT back on the VNA after a successful calibration it will probably look like the image below. These smith chart images for the female SHORT and OPEN are based on s1p data from another Kirkby cal kit. i.e. the SHORT will look like a short that is shifted about 42ps from your reference plane once you fit it back on the VNA after a calibration.

[Bud]

Ok, so after i finalize the calibration by pressing "DONE 1-PORT CAL", i set the VAN to Smith-chart to verify if calibration is correct.
I do this by attaching the SHORT again and check if the Smith-chart gives me a point at the short-position.
However, i don't get a dot at the short position but a line reaching from short to almost infinit on the upper, outer pure inductor circle.
Similar, just mirrored is displayed when the OPEN reference is connected.

For compensation, i applied a port extension of 58.14 ps and get the expected results (dots) with all 3 calibration standards.

I thought that with the complete calibration data on the floppy disk, there would be no need for manual port extension entry?

You should not do this. Why? Think about what your VNA will show if you connect an ideal Short or ideal Open. They will Not be at zero and infinity dot position as they should, because you offset the chart by 58ps. Therfore any measurements you take with such port extension applied will be invalid.

[TheSteve]

Another thing that irritates me is that the 50 Ohm references are 49,5 and 51,1 Ohm instead of "50,0".
I would expect to get better quality references for that price?

On my "out of spec" SMA kit my female load is 51.05 ohms and my male load is 49.25 ohms.

And I do get the expected smith chart results G0HZU suggested you would.

The kit cal info does have a max frequency entered into it that was supplied for my N9912A, I'm not familiar with the 8753ES but is it possible Dr Kirkby entered 3 GHz into your data for a max frequency instead of the spec'd 7 GHz or your 8753ES's 6 GHz.