So what is ideal for a simple, short, 1x probe that goes to 0.025 square pin skt - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: May 11, 2017, 02:22:54 am
content: What I'd like to find or make is a BNC to 0.025" square pin socket type of probe. Maybe 12"-16" long so it would be pretty compact. Not for use with 50 ohm terminated inputs, but for use with 1M. I was reading about how a lossy cable would be important. Is that all that is needed? BNC adapter, lossy cable, small pigtail to square pin sockets?

author: tautech
author_rank: Super Contributor
timestamp: May 11, 2017, 02:43:39 am
content: For short leads that fit the 0.25" pins on Tek grabbers I just used crimp on 0.25" females with a short lead strpped and formed into a loop and soldered/tinned that way to connect to a probe grabber.

author: ajb
author_rank: Super Contributor
timestamp: May 11, 2017, 11:52:28 am
content: It depends on what sort of performance you're after. For basic low-ish frequency poking around, I made some probe tip to flying lead adapters some time ago using probe tip to BNC adapters (I had a 10-pack, and had a hard time imagining ever needing half that many at once!). The ground lead is soldered directly to the adapter shell, after filing a small notch in the front lip. The inner lead connects to the center pin of the BNC side using a JST VH terminal, which fits nicely inside the adapter. A couple of female header socket terminals on the other ends of the wires, a bit of heatshrink, and bob's your uncle.Of course the length of the wires is a compromise between convenience and signal integrity, but since I'm using these where I'd otherwise use a clip-on ground lead I'm not too worried about it. I like this solution better than some sort of dedicated probe because it's easy to swap out with a hook adapter or ground spring as needed when poking around at something, it takes up less space, and it's small and cheap, being made from parts on hand.

author: nfmax
author_rank: Super Contributor
timestamp: May 11, 2017, 12:38:04 pm
content: I'm using Keysight N2863B probes, and there is an accessory available that does exactly this - part number 0960-2923. You can order them direct from Keysight, as the distributors don't seem to stock them. Other manufacturers may have equivalents.

author: alank2
author_rank: Super Contributor
timestamp: May 11, 2017, 12:58:47 pm
content: nfmax - I've seen 10X probes with pigtails (probemaster has one) or pigtail adapters. What I am really going for is compact though. I did some testing with two that I have. One is one of the cheap BNC to fake pico hook type of cables I think I paid $5 for, and the other is one of the cheap P6100 probes that I cut the probe end off and soldered on some pins for breadboard use. The P6100 BNC end that I kept does have an adjustment in it and it adjusts to improve what a square wave looks like. It hits the -3db point at around 30 MHz (which is fine) and has less ring and a nicer looking square wave than the BNC/hook cable does although the BNC/hook cable can go to around 36 MHz until it hits the -3db point. Is there anything to be learned from this? Is the lossy cable in the chopped off P6100 BNC end what is dampening the ringing? I am surprised the adjustment in the P6100 BNC end is useful without probe side parts, but perhaps there aren't any? I'll post some pictures of these in a little bit. Both of my cables are about 40" long. Would performance be better if they were a little shorter? Worthwhile enough to shorten them?

author: alank2
author_rank: Super Contributor
timestamp: May 11, 2017, 01:04:31 pm
content: pics

author: alank2
author_rank: Super Contributor
timestamp: May 11, 2017, 01:06:26 pm
content: ajb, those look nice, I like the heat shrink and color coding!

author: georges80
author_rank: Frequent Contributor
timestamp: May 11, 2017, 05:10:48 pm
content: https://www.eevblog.com/forum/testgear/o'scope-probe-adapter-where-from/msg623839/#msg623839cheers,george.

author: alank2
author_rank: Super Contributor
timestamp: May 11, 2017, 05:43:46 pm
content: More testing shows that the pigtail/cheap cable has quite a bit of ring in it. Still a square wave at 5 MHz on it doesn't look too bad other than the obvious ringing, but much higher and it becomes quite a bit less discernable that it is a square wave. The chopped P6100 BNC probe does much better up to around 15 Mhz where the square wave still looks pretty good, going much higher than that however cause it to look more and more sine like and less square like...

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: May 12, 2017, 12:25:58 am
content: One of the big e/e manufacturers (can't recall which) was introducind a line of controlled impedance interconnects around the 0.025" post at some time about end of 80s.When you ordered the sample kit, you got a BNC-f to single 0.025" jack adaptor and a beautiful, shielded dual 0.025" with RG-178 pigtail, onto which I crimped a SMA-f.Access to a well sorted connector collection can also help. I found a little can full of pin contacts from a french Hi-Rel rectangular connector series, which fit exactly into the Tek P6243 and similar probes' sockets.I used a number of them to make extensions, adaptors for ATE-type needle probes and so on.For less demanding applications, I use a Pomona part which is basically a BNC-jack with strain relief and two pigtails with miniature probe plugs, which I replace by whatever I need. (Mil-Pins and -Sockets, 0.025" jacks and posts (sometimes with the little coloured plastic boots from Hirschmann 1mm and 2mm plugs for handling).Also (might be most universal), MC from Germany made a part that fitted onto any standard modular (5mm) probe which terminated in two thin flexible leads with 2mm plugs. I did not find it in their catalogue so it might be a custom part. I got a handful on Ebay and I'll cling to them like hell. The 2mm plugs can be easily replaced as with the Pomona part.BTW, single plastic shrouds for 0.025" contacts are available from SKS Kontakttechnik, which took over the T&M product line from Hirschmann.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: June 02, 2017, 06:49:14 pm
content: A current adaptor from 5mm modular probes to 0,025square is available from LeCroy/Digikey:Digi-Key PK106-2-ND