I see they also have a Tek 7854 in the previous picture, lot 19 in the catalog here: https://bid.tmcauction.com/auctions/catalog/id/23165/ I wish I was a bit closer to Sacramento. - Bob Headrick

As it turns out, I have the Tektronix 2645A with serial number B010101. I picked it up at Surplus Gizmos for ~$150 and have probably spent that much more in caps, keeper battery and probes. Had I know

Efficiency as measured by voltage transfer, it would be interesting to compare power transfer efficiency. With 20mA on the driven LED is it possible to get even a few microamps of output current? - Bo

This is way off topic, but RG-174 is 50 Ohms. RG-179 is a similar size but 75 Ohms. Folks offering RG-174 as 75 Ohm should probably be avoided.... In this application it does not matter, the instrumen

It is actually Thingiverse. Try this link: https://www.thingiverse.com/search?q=tektronix - Bob Headrick

Surplus Gizmo's in Hillsboro, OR has a 7B92A for $25, you might contact them and ask if it has been tested. See http://www.surplusgizmos.com/ - Bob W7OV

Personally I have a 2465a that has some blown caps (repairs in process) and a 2225. I gave away my drawers of tubes back a couple decades ago.... I do appreciate the design of the old 500 series scope

Surplus Gizmos in Hillsboro, OR has a 7B15 for $65. See http://www.surplusgizmos.com/ They do not have it listed on their website, but I saw it on the shelf the day before yesterday (with a bunch of o