Your custom wiring is the problem, do the compensation at the measurement site. Maybe use 50 ohms scope input, then use coax? Most of my scopes have a switch to make them 50 ohms. The good probe manufactures (spelled Expensive) have had to design their own cable. Cheap scope cables, for instance may create noise just by being moved, like if you were monitoring something vibrating. A shaker or motor test? A sort of piezoelectric effect. Tek warns that in some of there probe brochures. Search their site for info? 2010 8:34 AM, Mark Rages wrote: > On Wed, May 12, 2010 at 7:49 PM, Forrest W Christian wrote: > >> In my R&D and test environments, I seem to quite often need a 'custom' >> scope probe.. For instance - RJ45 'probe' end, 10X. To date, I >> basically sacrifice an inexpensive 10x probe and end up with an ugly and >> sometimes not all that mechanically stable (long term) cable with the >> scope probe basically being turned into a 'bump' on the cable. I >> really dislike doing this because it just isn't the right way. >> >> I'd love to find a pre-manufactured (or kit) 10x probe circuit board >> which basically plugs into the scope and has all the compensation >> circuitry, to which I can connect my own cable and/or connector to it. >> Even flying leads would be an improvement mechanical. >> >> I asked a few months back about schematics or similar, and got a couple >> of responses, but realize that really what I'm looking for is something >> I don't have to mess with designing another circuit. I'm ok with >> soldering one up if I need to, but really want the 'hard work' done for >> me... >> >> Is anyone aware of a 10X scope probe which is reasonably inexpensive and >> terminates to flying leads, or is provide-your-own-cable instead of the >> traditional electronics-in-a-real-probe design? >> >> -forrest >> > The eevblog had an interesting segment on building a high-voltage > scope probe. Not exactly what you're asking about, but worth the ten > minutes to watch. > > Regards, > Mark > markrages@gmail > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist