If you get the "Sorry, the file cannot be displayed. There seems to be a technical issue ..." error when trying to view an image, a workaround is to click on the cog icon in the upper right side of the media viewer, and then select "Disable Media Viewer". We are aware of the problem and are looking for a solution.
The Tektronix 535 is a 15MHz oscilloscope that accepts letter-series and 1-series plug-ins. There is also a 535A. There are two timebases and triggering is done with a Schmitt trigger made of a 6DJ8 tube. The vertical and horizontal output amplifiers are all tube and non-distributed. The 535 is functionally the same as a 545, but with half the bandwidth. Early 535s were brown. Later ones were Tek blue. All 535As are blue. Early 535s had selenium rectifiers.