Re: 11801C and the T1331 error: lost factory TB calibration data.
I plan to browse chipxs regularly. This is hardly an NOS SD-24. Last cal was 2011 due next in 2013. Measured rise times are ~14 ps with uncertainties of 4 ps. I am extremely pleased with it.
I did some calculations this morning. With an adjustable shorted stub on a 0.0001" reading micrometer head, the reflection would shift ~25 femtoseconds for each 0.0001" movement.
At 5 ps/div and 5120 samples we've got samples at ~10 femtosecond intervals. So measuring timebase nonlinearity is rather challenging.
I don't think any piece of gear I have has been as just plain amazing. The idea that it is 30 year old technology blows me away. I just wish I had better service data for it. I'm quite alarmed that after being idle for a few months I now have display jitter even after warming up for several hours.
I'd love to know who designed it and whether they are still alive.