Teardown and calibration checking of a Keithley 480 Picoammeter Dave got from ebay.
This was supposed to be a repair and troubleshooting as well, but Murphy had other ideas.
Keithley 480 User & Service Manual
Forum Topic HERE
Dave compares the FFT modes on 7 different oscilloscopes: Rohde & Schwarz HMO1202 Series Tektronix ...