Author Topic: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review  (Read 13258 times)

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Offline TurboTom

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Re: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review
« Reply #25 on: May 09, 2017, 08:31:39 pm »
Initially, we (my collegue -- the "real" EE -- and me, the "crazy" physicist...) also questioned our setup and what errors we might have done when we found this discrepancy. Truth is, the BNC cables we used are good enough at the frequency range of that device that we shouldn't see any deviations of the delay. I checked the cables with my HP 8753C and they perform flawlessly up to > 1GHz delay-wise, above that some tiny wiggles can be observed, but still no significant deviation from the general phase delay, up to the 8753C's limit of 3GHz. Btw, the 8753 doesn't show the "funny" incline of the delay plot in logarithmic frequency mode.

Of course, the delay will be introduced by the length difference of the two cables, that was the intended effect. I also agree that the 4630B (like probably most VNAs) primarily evaluate phase (by measuring the balance between the I and Q signals) but can easily calculate phase delay by dividing continuous phase by (360°*frequency). If the DUT (cable's dielectric) hasn't got any significant dispersion in the observed frequency range and there aren't any resonances otherwise, this figure should be fairly constant as it actually is, provided the linear frequency scale is selected (see attached photo).

For comparison, I attached the phase measurement of our two cables as well, both with linear and with logarithmic frequency scale. These figures are both correct. To me, it actually seems that Anritsu erroneously used the frequency reading from the linear scale to calculate the delay in the logarithmic display, which would also explain that right at the end of the logarithmic delay plot, the reading drops back to the approximately correct range.

Nico, what's the firmware date and revision of your 4630B if i may ask?

Thanks and all the best,
Thomas



Edit: Added the delay plot with logarithmic time scale for better comparison.
« Last Edit: May 09, 2017, 08:34:37 pm by TurboTom »
 

Online nctnicoTopic starter

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Re: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review
« Reply #26 on: May 09, 2017, 09:36:15 pm »
I'm getting similar weird readings on mine. Also my MS4630B only wants to measure the delay up to 100MHz  :-//
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Omicron

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Re: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review
« Reply #27 on: August 04, 2017, 07:45:54 pm »
I have one of these as well. However I think mine is faulty. The traces are really noisy in the region from 10Hz to 50KHz or so, jumping up and down by about 10dB. Calibration does not flatten out the trace in this band as it does for frequencies above 50KHz and the calibrated trace is just as noisy. I'm assuming there must be a fault in the LF part of the analyser. Unless I'm missing something obvious? I've only spent about an hour playing with the unit.

Has anyone stumbled upon a service manual for these things?

[Edit] Ah! My bad! I need to select a longer sweep speed if I want to see the lower end of the spectrum. Obvious in retrospect! :-)
« Last Edit: August 04, 2017, 08:43:31 pm by Omicron »
 

Offline R_G_B_

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Re: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review
« Reply #28 on: August 04, 2017, 11:01:51 pm »
I have the predecessor to this network analyzer.

And it shows something similar in the low frequency band
Not sure if it's could be the resolution bandwidth settings Or sweep time settings.

R_G_B_
R_G_B
 

Offline Omicron

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Re: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review
« Reply #29 on: August 04, 2017, 11:33:39 pm »
If I turn the sweep speed down the trace clears up. When I set it to 100 seconds for example then I get a pretty clean trace all the way down to 10Hz. It makes sense if you think about it, the sweep needs to be slow enough for it to be able to capture a few complete sine wave cycles at each measurement point. So the lower you go the more time it needs.

I'm still learning how to use this device, but I'm pretty sure now mine is working as intended.
 

Offline mrf245

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Re: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review
« Reply #30 on: April 23, 2018, 12:33:50 am »
I bought some MS4630B with TRB (secondary receiver port), some of them are with issues such as LCD fault and panel broken. Now trying to repair it.
BH7JUO Mark
 

Online nctnicoTopic starter

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Re: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review
« Reply #31 on: April 23, 2018, 08:28:36 pm »
Replacing the LCD panel shouldn't be hard. It is a standard VGA panel.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online nctnicoTopic starter

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Re: Anritsu MS4630B 10Hz-300MHz network analyser teardown/repair/review
« Reply #32 on: August 20, 2022, 12:27:16 pm »
Ressurecting my old thread...
A couple of years ago I bought a Prologix ethernet to USB adapter to get screendumps from a Tektronix frequency counter. Since then I have created several other Python scripts to get screendumps from other equipment as well. The latest addition is the MS4630B.

Or sort off... it turns out it can't really do a screendump over GPIB. It can only print. I have looked at printer emulation in software or hardware but that is either gone, expensive or requires different hardware. So I ended up creating a Python script that reads the data, plots a graph and saves it to disk. The attached script works OK for x-y plots both linear and logarithmic. It took a bit of effort to make Matplotlib use sensible numbers for the x axis.  Polar and smitch charts aren't implemented.

Some examples:





Edit: added updated script which also shows the time + date and allows for an (optional) title using a -t option on the command line.
« Last Edit: August 21, 2022, 04:52:09 pm by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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