Well, yes, that's how capacitors work :) Or did you mean, self-resonant at a particular frequency? Above that frequency the cap would appear inductive, though, so I'm not sure that would help.

On that auction place. Price seems high but maybe not to someone who really needs one ;) https://www.ebay.com/itm/Vintage-Tektronix-113-Delay-Cable-for-Type-N-4S2-Sampling-Oscilloscope-Plug-Ins/133017

Where are you located? (I presume in the US from the United Package Smashers comment)?

Good point, I forgot your 1S1 is already 50 ohms. What is the period of that ringing? That may help locate something that's the right electrical length. Track on the probe PC board maybe? I agree, no

That's a lot of ringing (and it persists for a long time, too)! For the "direct" test, did you also have the tee with the 50 ohm terminator attached? (Is the ringing from the probe itself or from the

Thanks Albert. I KNEW I had seen that phrase somewhere in all my manuals, just couldn't find it! :) I've been hot-swapping them, at least the S-1 and S-2, multiple times without incident. In fact, I'v

True, unless specifically designed for it, which is why I asked.

Is it safe to remove or install an S-1 through S-6 sampling head from its plug-in without turning off the scope? There is nothing mentioned in the manuals for the various heads (or plugins, like my 3S

I wonder if it's possible to report him to ebay (selling items that are not as described)... On the other hand, they are unlikely to care since all they are interested in is their hefty commission.

Thanks. For now I'm trying to achieve the fastest possible risetime and a not-too-ugly flat top. I have somewhat achieved that already.... I can reduce the overshoot and ringing by adjusting the trimm

True... but if this were the source of the ringing, then wouldn't I see substantially less ringing, and a corner closer to square, on the S-4 25 ps sampling head compared to the S-2 (75) or S-1 (350 p

That is true, but Bodnar's pulser is a full order of magnitude faster than mine (30-40 ps vs. 380) and I'm sure nothing is what it seems at that speed. Anyway, I may just stop here rather than drive m

Any thoughts on what's causing the ring with the 2 ns period at the start of the flat top? Maybe the short but unavoidable length of exposed center conductor where the charge line connects? https://ti

Thanks :) I stuffed it all into the 5 x 2-1/4 square Minibox, including a 6 ns semirigid charge line. Displayed 10-90 risetime is just under 400 ps on a 75 ps sampling head. Flat-top could be flatter

I wondered what that thumping sound was... it was Tom banging his head on his desk from 2000 miles away :)

I bought ten BFR505 transistors which are supposed to be faster than 2N2369's. Unfortunately they come in SOT-23 packages (i.e. smaller than a mouse turd). I had a fun time installing one into my puls

Thanks :) While comparing the S-1 to the S-2, I discovered another reason to prefer the diodes I used.. I was swapping cables around and plugged the avalanche pulser (at least 10 volts) into the S-1 w

Thanks... but I broke the nylon holder, and those diodes are rather prone to destruction (which is how I got the S-1 in the first place). Also they are REALLY tiny and I just don't have the mechanical

Thanks, Ed & dan. I will check R18 in particular. But I apparently have overthought the problem. It's mechanical, not electrical! I posted three pics in "Sampling with 3S2" (and set the order to most

Thanks! Feel free to keep sharing your knowledge ;) I have never played with varactors so that C-V curve didn't even occur to me... so what happens to the junction capacitance under forward bias? But