ZLG ZCP30 - 50MHz x1/x10 AC/DC current probe

[TopQuark]

Hi, originally I wasn't going to review this probe, but a couple of forum members expressed interest after seeing me use it in other posts, so I thought I'd give it a review anyways.

The reason I hesitate to review this product on this forum, is the company that makes the probe, ZLG, does not seem interested to sell their products outside of China at all. I don't think many would have heard of the company, but they actually produce some decent products, including 4ch 500MHz scopes, programmable AC source, high channel count scope-recorders etc. and a lot of embedded computing stuff.

You can have a look at their website if you want, but I don't think they even have an English version of their website. https://www.zlg.cn/

Anyways, the elephant in the room for current probes is always the price. I now own two of these probes, and I paid 8439 RMB (1244 USD) for my first one on the official ZLG Taobao shop during a seasonal discount, and I paid 8300 RMB (1224 USD) for my second one, bought from a third party taobao shop, price negotiated down.
Official shop: https://item.taobao.com/item.htm?id=602950143769
Third party shop: https://item.taobao.com/item.htm?id=692674819925

Claimed specs and instruction manual (Chinese Only) : https://www.zlg.cn/data/upload/software/Osc/ZCP30.pdf

Banner spec is
- DC to 50MHz BW
- 1V/A and 0.1V/A sensitivity ranges
- 5A and 30A RMS full scale ranges
- 50A peak current

Testing results will follow

[TopQuark]

Unfortunately I blew up my DIY high BW DC load capable of generating tens of A load steps within a us. So we will have to settle with the Siglent SDL1000-X's 2.5 us/A slow load steps.

I tested my two ZCP 30 together to try and spot differences.

Load steps don't show any sign of gross overshoot, the ripple riding on top of the load step high load waveform is from the combination of cheap power supply and the Siglent load, not artifacts of the current probe.

I then hooked the two ZCP30 in-line with my function gen output, and used the scope's 50ohm termination as the load and current shunt. I ran two bode plots in x1 and x10 settings, the voltage scale on the scope is normalized so that the frequency response of the current probes have unity gain at DC.

The response looks good in general, with a bit of gain fluctuation towards the BW limit of the probe, but the the fluctuation is within 3dB below 50MHz, and the scope's calculation of the probe bandwidth is slightly over 50MHz, so you do get the 50MHz of BW you paid for, which is nice.

[TopQuark]

Next is noise measurements.

I ran test in x1 and x10 mode, with full BW of my scope (500MHz) and with 20MHz BW limit.

Note that I didn't place the probes in a shielded environment, I just kinda left them on my table, to the probes are probably slightly better than what you see here in terms of noise.

[Martin72]

Hi TopQuark,

The instrance probe we both had, got the problem of overshoots due to the impedance mismatch.
(Bodnar pulser, internal 50 ohm as load then measure)
What about the ZCP30, can it handle it better?

[TopQuark]

Don't have a Bodnar, have to settle for the SDG2000X, with rising and falling edge of 8.4ns.

The waveform reproduction is not absolutely perfect, but there's no gross overshoot or "big lies" compared to the instarance.

[TopQuark]

Same test in 1x mode