Link Instruments DF-600 Active Differential Probe - Page 1
Forum section: electronics / testgear

author: slugrustle
author_rank: Frequent Contributor
timestamp: July 14, 2023, 04:07:58 pm
content: I'm looking around for a high speed, low voltage active differential scope probe that can plug into a generic oscilloscope. The Link Instruments DF-600 looks good to me in terms of price ($299) vs. performance (600MHz differential, 400MHz single ended), but there is no manual on the product page, and I'm not sure how robust the input connections are.Has anyone here used a DF-600 probe? How well does it work?https://www.linkinstruments.com/df600.html

author: JehTeh
author_rank: Contributor
timestamp: July 28, 2023, 02:07:19 pm
content: I have a couple - they seem to be OK, although I was seeing little bit of ringing on some faster edges compared to some 1.5G passive probes (900ps, spec for rise time is 300ps) but it could have just been a sloppy measurement setup on my end. I have not tried them on anything higher-voltage than ~5v.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 28, 2023, 02:12:23 pm
content: This might be an option for you:https://www.eevblog.com/forum/testgear/12-ghz-active-probe-project/

author: slugrustle
author_rank: Frequent Contributor
timestamp: July 28, 2023, 03:56:46 pm
content: Quote from: JehTeh on July 28, 2023, 02:07:19 pmVery neat. What does the input side of the probe look like? Especially the connection points for the little attachments that come with the probe. It's not at all clear from the website photos... all I see is one wire sticking out. Maybe that's the ground pin?

author: slugrustle
author_rank: Frequent Contributor
timestamp: July 28, 2023, 05:15:22 pm
content: Hey, what do you know, K and H Products has a page about this probe with a PDF that makes its operation more clear:https://www.kandh.com.tw/df-600-differential-active-probe-df-600.html.

author: JehTeh
author_rank: Contributor
timestamp: July 29, 2023, 08:56:39 pm
content: Quote from: slugrustle on July 28, 2023, 03:56:46 pmThe probes have a GND/DIFF pin (there is a selector switch) on the side relatively close to the tip. There is another GND only pin further back. You can see them in this picture:see 'PXL_...' attachement*edit attachements got all screwed up, just ignore them. See here:https://imgur.com/a/94sq5cZ

author: slugrustle
author_rank: Frequent Contributor
timestamp: July 30, 2023, 01:36:36 am
content: Thank you for the excellent picture and explanation. I did not anticipate the LED!

author: points2
author_rank: Regular Contributor
timestamp: October 12, 2023, 02:53:18 am
content: Hi,I received a DF-600 a few weeks ago. So far, very nice !I'm not a pure tester (no money for that).Just by reading this thread I thought this diff probe would be a good deal => so far, very good, awesome price/pref ratio.I was just looking for a "cheap & good perf" diff probe to do measuments at PCB level, thus 5V maxand the diff probe is more than perfect !Question to anyone : why main/all diff probe are rated "high voltage" ?Who are the guy that need a diff probe to be proof up to 600V ? (just an ex.)PCB level is 5Vmax...so what's the heck to pay for a diff. probe that handle 300V/600V ?Those high voltages are managed by electrician... quite far from electronician dealing with V<10VRgds

author: alm
author_rank: Super Contributor
timestamp: October 12, 2023, 12:48:50 pm
content: Quote from: points2 on October 12, 2023, 02:53:18 amThere are two classes of diff probes. High voltage, moderate bandwidth differential probes up to 100 MHz or so going up to hundreds of volts, and high frequency low voltage differential probes that go up to a few GHz. There used to be a third class of low bandwidth, very low voltage differential probes/preamplifiers like theTek ADA400A, but not many of those are designed anymore. The first group is often used for power supply design, like the primary side of a flyback converter. Or in inverters. They are also sort-of usable for lower voltage circuits at the expense of noise and bulky size. The second group is generally used for fast differential digital buses like USB or PCI Express. And the last group was mostly used for low level analog circuits like analog audio, or for magnetic read heads like on tape drives and hard drives.The high voltage type is the easiest to make so I guess that's why the low end brands are just making those. All the big scope brands are also selling low voltage, high frequency differential probes, but you may not like the price.