Well it is probably somewhat depatable as to how much one should care about calibration of an CRO, especially today. The precision is somewhat inherently limite

Well it is probably somewhat depatable as to how much one should care about calibration of an CRO, especially today. The precision is somewhat inherently limited by what you can resolve with Mk1 eyeball on the screen. I have an 4 channel Kenwood CRO on my bench that is intentionally completely out of cal as removing the burned out vertical amplifier gain hybrid modules (complete unobtanium, although one might be able to handcraft that as a SMT board with modern components) makes the thing work for some value of “work” (no vertical vernier, the cal position being on the order of 2x off). But well, it works for looking at powersupply noise in relation to digital signals and similar stuff. In contrast to that one somehow expects that on a random digital scope functions like measurements work and are reasonably in-cal. And the calibration on digital scopes tends to involve possibly undocumented software, not turning trimmer pots/caps of obvious function while having tongue at a right angle.