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Author Topic: 50Khz to 1Ghz Oscilloscope Calibrator  (Read 5296 times)

Offline briansalomon

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50Khz to 1Ghz Oscilloscope Calibrator
« on: 04-17-2018 -- 19:00:03 »
My lab need to replace our old scope calibrators.

What do you like to cover scopes up to 1Ghz?
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Offline CalLabSolutions

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #1 on: 04-17-2018 -- 19:37:02 »
You can pick up an HP 8648 for cheap and it will more than cover that frequency.  If you convert the dB leveling error to linearity then compare the TARs you will see it is more than accurate enough that you don't need a power meter..

If you are looking for new.  The Keysight MXG's are pretty impressive.  We have sold a couple to some of our customers to support the Tektronix MDO-3000 and MDO-4000 Scope / Spectrum Analyzers.

Mike.
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Offline silv3rstr3

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #2 on: 04-17-2018 -- 19:41:47 »
The Fluke 9500B with scope heads is my favorite.  There is a 600MHz, 1.1GHz, and 3.2GHz option and if you get the 9560 active head it can output 6GHz.  The 9500 with all the heads makes automating oscilloscopes in Met/Cal very efficient.  The Fluke 5520A and 5522A scope options are very similar and easy to use. 

We still occasionally get some of those old Tektronix SG504's in for calibration and surprisingly they still work good.  The newer standards + automation allows me to run multiple stations at the same time while calibrating something else manually.
“They are in front of us, behind us, and we are flanked on both sides by an enemy that out numbers us 29:1. They can’t get away from us now!!”
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Offline griff61

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #3 on: 04-17-2018 -- 21:26:29 »
I'm begging for a few Fluke 5522As with the 1.1GHz scope package. Our experience with the 9500 is that the heads are prone to failure by design and Fluke won't cough up the schematics etc to repair them.
The same design flaw is in the 9640 source head as well.
Almost seems...intentional
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Offline briansalomon

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #4 on: 04-17-2018 -- 22:31:44 »
My boss is looking at the Fluke 5820A.

Any thoughts?
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Offline CalLabSolutions

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #5 on: 04-18-2018 -- 01:09:19 »
The problem with the Fluke 552xA Scope output is that it is not accurate enough to calibrate today's scopes.  And the normal output is noisy as hell.

Also.. Check out the new Transmille 401x.  We built drivers for it in Metrology.NET.  I think it is going to give the 5522A a run for its money.

Mike
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Offline CalLabSolutions

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #6 on: 04-18-2018 -- 01:10:58 »
My boss is looking at the Fluke 5820A.

Any thoughts?
It has the same DC Volts accuracy problem as the scope output on the Fluke 552xA.

Mike
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Offline griff61

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #7 on: 04-18-2018 -- 01:51:27 »
The problem with the Fluke 552xA Scope output is that it is not accurate enough to calibrate today's scopes.  And the normal output is noisy as hell.

Mike
What DC volts accuracy problem?
I've never seen either of those problems with the 5500 series. The 5820 had a design flaw with the switches. If you didn't exercise them regularly, it would fail. It was sort of half the bang for your buck as calibrators go and low reliability due to design error.
I haven't run across any oscilloscope in the 1.1 Ghz range and below that a 5522A wasn't accurate enough to calibrate. Certainly not anything that Tektronix, HP or Lecroy puts out, as we've calibrated lots of those. Both here and at commercial labs. Most of today's newer scopes are essentially calibrated with DC levels, because they're essentially digital signals referenced to DC, the 5522 is very capable for that, the frequencies over 1.1 GHz we provide with signal generators.
Not clear on what noise problem you're referring to, as we don't use calibrators for low noise applications
But to each their own I suppose, I'm always willing to learn something new
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Offline Hawaii596

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #8 on: 04-18-2018 -- 15:01:31 »
We use 5520A with 1100 MHz Scope option. We also have a couple of Wavetek 9500/3200 with 9530 (3.2 GHz) heads. Between all of those, they seem to handle all of the scopes we support (large and diverse customer base) up to 3.2 GHz.  For scopes above that BW, we use microwave generators externally monitored with RF Power meter/splitter.

I have also seen in a previous life when calibrating scopes (at an HF radio manufacturing facility) there was sporadic EMI that made a mess of measurements. When one of those radios got keyed, even though it was shielded coax into a load, it made a messy adder to my otherwise clean waveforms.  This can be an issue in many forms.  Mine was a nice "clean" HF band (0.5 to 32 MHz) sine riding on my sine signal.  In other environments, it can be other EMI mitigants.
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Offline silv3rstr3

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #9 on: 04-18-2018 -- 15:59:41 »
I'm begging for a few Fluke 5522As with the 1.1GHz scope package. Our experience with the 9500 is that the heads are prone to failure by design and Fluke won't cough up the schematics etc to repair them.
The same design flaw is in the 9640 source head as well.
Almost seems...intentional

Luckily I haven't had any problems with the active heads.  I calibrate a lot of them for our company every year.  What's weird though is the last 2 years in a row the 9500 base unit intermittently fails self test.  We had to have it repaired twice now and as a result we had to shorten the calibration interval this year.  I didn't know that about the LPNX.  I'm still using the 3335A and trying to push to get the newer generator.  I am tired of doing spectrum analyzers manually.  Automating those would save a lot of time. 


“They are in front of us, behind us, and we are flanked on both sides by an enemy that out numbers us 29:1. They can’t get away from us now!!”
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Offline CalLabSolutions

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #10 on: 04-19-2018 -- 16:11:25 »
The problem with the Fluke 552xA Scope output is that it is not accurate enough to calibrate today's scopes.  And the normal output is noisy as hell.

Mike
What DC volts accuracy problem?
I haven't run across any oscilloscope in the 1.1 Ghz range and below that a 5522A wasn't accurate enough to calibrate. Certainly not anything that Tektronix, HP or Lecroy puts out, as we've calibrated lots of those. Both here and at commercial labs. Most of today's newer scopes are essentially calibrated with DC levels, because they're essentially digital signals referenced to DC, the 5522 is very capable for that, the frequencies over 1.1 GHz we provide with signal generators.
Exactly.  Look at the TURs of the DC Voltage output of the Fluke 552x and 582x.  Many of today's scopes are better than the 1% and 2% scopes of yesteryear. 
We have helped one of our customers move from the 9500 to 5820 only to discover the TURs are not as good with the 5820.  But in the end, they did the switch anyway because it was less paperwork for TUR issues than recall issues when a head failed calibration on the 9500.

The noise is out of the Normal Output.  Connect it to a scope, turn off averaging then watch it bounce ever second or so..

Mike
« Last Edit: 04-19-2018 -- 16:15:18 by CalLabSolutions »
Michael L. Schwartz
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Offline griff61

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #11 on: 04-19-2018 -- 20:42:56 »
Exactly.  Look at the TURs of the DC Voltage output of the Fluke 552x and 582x.  Many of today's scopes are better than the 1% and 2% scopes of yesteryear. 
The noise is out of the Normal Output.  Connect it to a scope, turn off averaging then watch it bounce ever second or so..

Mike
DC is bouncing on the Normal output of a 552X?
That sounds like a problem with your instrument, not every instrument. I have never seen DC bounce on a 55XX series calibrator.
The 5522A has a One Year absolute accuracy of 12ppm + 20uV from 0 to 32.999VDC,
As far as DC gain goes, which ones have better than 1% gain? The Tek DPO7000 series are 1%, MDO4000 series are 1.5%, DPO/MSO5000 series are 1.5% and the MSO54/6/8 are 1%
Those are the baseline best ratings according to Tektronix
Keysight specifications are: InfiniiVision 1000 X-Series, 2000 X-Series are 3%FS
InfiniiVision 3000T X-Series, 4000 X-Series, Infiniium S-Series, V-Series Oscilloscopes, Z-Series Oscilloscopes are 2%FS

Myself, I’m looking forward to three brand new 5522A/1GHz calibrators
If my CERB survives, that is…
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Offline silv3rstr3

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #12 on: 04-19-2018 -- 22:28:04 »
Exactly.  I haven't seen a oscilloscope come through here that had an accuracy of less that 1%.  And this place has a lot of the newer Keysight and Rhode & Schwarz.  The other good thing about the 5522A verses the 5520A is that they put a fuse on the bottom of it so that you can't blow up the input.  I saw people do that a few times at my previous employer and it was like $7,000ish to fix it!!  The fuse on the 5522A is just one of those blue Fluke fuse's which are a hell of a lot cheaper.  One of those guys was using it to measure temperature in an oven (Don't know why because we had a bunch of the handheld process calibrators) and hit the heating coil.  It traveled down the thermocouple and blew the input! 
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Offline CalLabSolutions

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #13 on: 04-20-2018 -- 04:19:19 »
The DC Output of the Fluke 5522A's scope output is not in the ppm range like the normal output. 
50 Ohms is -- 0.25% + 40 uV
1M Ohm is -- 0.05% +40 uV

When you do your Uncertainty budgets those numbers go up!
When you are testing the scope at lower voltages that 40 uV is more of a problem and so do your Type A uncertainties. (40 uV is a rectangular distribution!) 

Keep in mind, we are TUR's not TAR's.  And 17025 Accredited calibrations, these little things will kill you with a good auditor.

It was an eye-opening event for me when I discovered the 5520A was not accurate enough to calibrate the Fluke 87's on capacitance. 

Same thing when we compared the Uncertainties of the 55xx Scope Output to the 9500.

That said... I miss the old Milstandard days!

Mike
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Offline ck454ss

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Re: 50Khz to 1Ghz Oscilloscope Calibrator
« Reply #14 on: 04-20-2018 -- 13:55:01 »
The DC Output of the Fluke 5522A's scope output is not in the ppm range like the normal output. 
50 Ohms is -- 0.25% + 40 uV
1M Ohm is -- 0.05% +40 uV

When you do your Uncertainty budgets those numbers go up!
When you are testing the scope at lower voltages that 40 uV is more of a problem and so do your Type A uncertainties. (40 uV is a rectangular distribution!) 

Keep in mind, we are TUR's not TAR's.  And 17025 Accredited calibrations, these little things will kill you with a good auditor.


Mike

So I may be missing something but why not just use the normal DC output on your 5520?  Nothing says you have to use the scope output for all measurements.  Most 33k and 17-20 procedures use a standard DC Voltage calibrator anyway for DC measurements? 

 

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