Micsig CP1003/CP503 100MHz/50MHz Current Probe

[Martin72]

Hi,

Trying to make an adpater for the bodnar pulser....
Of course, this will not work without losses, that was clear.
But the Amazon BNC to screw terminals are totally unsuitable for this - if they are in between, there is nothing left at the end that you could call a square wave signal...
Well, then another setup and this one is much better, the rise time is still under 1ns.
(Pictures from both will follow, forgotten)
Used this adapter with the Tekprobe.
The current is very small and "high frequency", two challenges that the Tekprobe can handle, see pictures.
Then the Micsig...
Tomorrow I will have my generator produce square wave signals at different frequencies, the current will then also be higher.
To be continued.

[amar87]

So i was not crazy........ it happens as well at your side.

[Martin72]

My aim with the "loan" was to determine whether there is a defect or whether this is actually the behavior.
I would have preferred yours to be defective.

[amar87]

i love it how you dremeled the deskew fixture........

[Martin72]

This was also necessary, otherwise most current clamps would not have fitted.

[Martin72]

Finally, a few measurements with the square wave function of the SDG1122X.
The phase shifts correspond well with what you could see on the bodeplot.
At 1Mhz you can see overshoots in the micsig, I think this is due to the impedance of 1M Ohm.
The Tektronix is clearly ahead in terms of signal fidelity.
I will soon be taking measurements in the "practicable" range, i.e. up to 500kHz, roughly the maximum switching frequency of appropriately constructed power supplies.

[Martin72]

I am now in contact with Micsig.
They wanted more pictures or even a video of how I measured it.
Because I had asked them how they had carried out their measurements in order to achieve such a smooth linear curve.
The vertical scaling with 0dB alone cannot be right.
And they promptly asked back why I was in the mid -30db range...instead of telling me how they had measured it.
Anyway, I took new pictures today and to show them that it can hardly be due to my setup, a new measurement with my tektronix A6302 and then another direct connection.
Let's see what they say.
In addition, I will soon be able to measure another "reference".
I have ordered a siglent CP6030 current clamp for work...

[amar87]

they also told me the same thing.... to make a video sadly i had no time to do this maybe next week it gets better.

[Martin72]

But I don't know why they want a video.
I think the pictures are enough.
Both current clamps have the same behavior.
Both current clamps come from different suppliers.
The setup is pretty much the same for both - well, then you could argue that you're doing something wrong.
However, the significantly better behavior of the Tek probe with the same setup speaks against this.
Micsig has not contacted me again after the other pictures, perhaps they are trying to recreate it themselves.
Next weekend I will make more practical measurements, these bandwidth measurements are more of academic interest.

[Martin72]

Still no answer from them...
Before starting new measurements, I took two other tek probes from work to home and compared them with my private one.
A nice to know, not more..

[earthwormjim]

This is the CP6030 from Siglent(Hioki), nearly same looking but more than fourtimes expensive (2070€ without VAT).
Same claimed accuracy of 1%, but, and this may be the pricedifference, +/-1mA in 5A range, +/-10mA in 30A range.(micsig: 10mA/50mA)

The CP6030 is not Hioki.  It is made by Cybertek, Cybertek HCP8030 is the equivalent.  People keep mistakenly attributing these probes to Hioki despite nothing in Hioki's lineup matching.

http://www.cybertek.cn/info/989

[Martin72]

Thank you for pointing that out, now some things are making more sense.
Then we also have the 500A current clamp from them, which is really good, I'm looking forward to the "Tek Clone" which should be here next week.
Speaking of which:
Next weekend I'll take a few more measurements, then I'll make the preparations to send it back.
Micsig didn't get back to me after I provided them with info and pictures, also they didn't answer my repeated request for their measurement setup, somewhat unprofessional behavior.
Somehow I am still tempted to test the 50Mhz version, perhaps the 100Mhz is too "ambitious" for the circuit (the entire measuring electronics are in the clamp), but in the moment my motivation is a little bit low.

[DaneLaw]

Thank you for pointing that out, now some things are making more sense.
Then we also have the 500A current clamp from them, which is really good, I'm looking forward to the "Tek Clone" which should be here next week.
Speaking of which:
Next weekend I'll take a few more measurements, then I'll make the preparations to send it back.
Micsig didn't get back to me after I provided them with info and pictures, also they didn't answer my repeated request for their measurement setup, somewhat unprofessional behavior.
Somehow I am still tempted to test the 50Mhz version, perhaps the 100Mhz is too "ambitious" for the circuit (the entire measuring electronics are in the clamp), but in the moment my motivation is a little bit low.

Micsig has a rep here on EEVblog, he is quite a frequent visitor & solid to the bone - when he says something or merely indicates it, he / Micsig certainly delivers...

[Martin72]

I can keep the current clamp for a few more days....

[Martin72]

The housing arrived "yesterday" and I have now built myself a better adapter.
I will test it later with the Bodnar pulsers, a short Bode measurement showed no significant differences to my previously built adapter version.
Edit:
As I´ve used the micsig first with this adapter, I´ll connect its usb power cable to my scope insted using the AC adapter.
Not a good idea:
The range button flashes, DC offset about 3V was visible and no other actions possible.
Then changed to the original AC adapter, everything works fine.

[Martin72]

With my newly built adapter, the risetime drops to under 750ps (previously around/over 1ns) - I wouldn't have thought that.
But that didn't do anything for the Micsig (pic 57 shown as ref A, both 10mA/div).
Even if you switch to 5mA/div on the Tektronix, the good display is retained (pic58).
If only the amplifier wasn't so huge, I would never think of getting another current clamp.

[Martin72]

Hi,

In the next few days I´ll send the probe back, I ´ve made some other measures, they looked ok.
So my verdict:

+Form factor, small builded
+Building quality
+High bandwith
+Degaussing function
+relative low noise
-Measure resolution
-Bandwith linearity
-Price

In my opinion, the last point is the most important.
Even back then I didn't understand why the version with the normal BNC connection costs twice as much.
The current clamp themselves are the same.
So I would say that if the CP1003B cost exactly the same as the non-B version, it would be a good current clamp for the money (if you ignore the non-linearity).
As it is, however, it is definitely overpriced and what is also a pity is its measurement resolution, which only provides usable results from 20mA/div.
Once again, the old Tektronix A6302/AM503 combination has shown that it can't be beaten.
I am still waiting for an affordable alternative, unfortunately the Micsig is not it.

Martin

[DaneLaw]

Even back then I didn't understand why the version with the normal BNC connection costs twice as much.
The current clamp themselves are the same.
So I would say that if the CP1003B cost exactly the same as the non-B version, it would be a good current clamp for the money (if you ignore the non-linearity).
As it is, however, it is definitely overpriced

Wasnt the price-drop on the non-B variant, down to a clearance sale, as it was founded on a dying interface standard, hence Micsig's UPI (Universal Probe interface) and only very few Micsig scopes from a certain production run, that lasted a short while had that UPI interface, as even Micsig own scopes, dropped it.

https://eleshop.eu/micsig-cp1003-current-probe.html

[Martin72]

Your link is showing the original price, it was drastically reduced during the sale, to half the price if I remember.

Edit:

It was 41% off:

https://www.eevblog.com/forum/testgear/micsig-cp1003cp503-100mhz50mhz-current-probe/msg5091109/#msg5091109

[Martin72]

Today the CP6030 from Siglent arrived for work, let's see how it performs, it's quite a bit more expensive.

[alm]

+Form factor, small builded

Thanks for your review! In terms of size, how does the size of the probe head compare to the Tek A6302? Can the Micsig probes fit a smaller wire loop? Because that's the place where I'm most often size-constrained. I'd love a DC-50 MHz probe the size of a Tek P6022 (an AC-only probe), but I don't think that exists. All competitors I've seen have a larger head than the A6302.

[Martin72]

Hi,

I've made a pic, will post it later.

[tautech]

+Form factor, small builded

Thanks for your review! In terms of size, how does the size of the probe head compare to the Tek A6302? Can the Micsig probes fit a smaller wire loop? Because that's the place where I'm most often size-constrained. I'd love a DC-50 MHz probe the size of a Tek P6022 (an AC-only probe), but I don't think that exists. All competitors I've seen have a larger head than the A6302.

tautech hugs his P6021 and P6022 close. 
Decades since their release they are still the standard all are compared with.

[alm]

I agree it's impressive. The Tek P6042, which is essentially the same probe that they're still selling today, was introduced in 1967, although I think the later amplifiers like AM503A/B were a bit less drifty. And I still don't think it's been surpass in size or noise level. The only thing that was improved was bandwidth which only helps for some circuits (like those 500 MHz passive probes).

[Martin72]

Size comparison....

For the siglent CP6030 I´ll open a  new thread, one thing:
The noiselevel is very good...