I was going to mention this again on my last project page but i am interested in what the hell this CRT i have is so starting this for a Chat and who knows where it will end and don't want to bore those not interested .
https://vintagetek.org/articles-and-scans/
Doing some research on the Tektronix T5640 after reading what i found i have some questions later on it
What it is below
............Part No 154-0418-00 Name T5640-201 Phosphor P201
Link to the Hunt for information
http://w140.com/tekwiki/wiki/T5640
Below is a simple drawing of my CRT wow that's different on any thing i have ever looked into .
Now i looked into the internal graticule it does have a line i can't see a grid that might of just been some plastic screen i would think this was a scope tube may be with Storage memory ? ..i am not to bothered about
Now a Question more than likely Steve you can answer P201 Now i know the P is for phosphor and the number after time in seconds ,Tektronix seems to have a different code 201 ?
EDIT............i just found this ( it can hold the trace for an hour after its been written to the screen ! it says due to its 2 screens it can either be used as a normal scope screen or as a storage screen...in our case of interest this thing might be able to do both SSTV and NBTV depending on what you use...how this is done needs more research.
https://archive.org/stream/tektronix_56 ... jvu.txt....
1963 boy you were right there Steve ...if i got it right you can write and erase to the screen sounds like a great idea for sstv !
5640 in the below pdf
The flood gun is new to me first i have heard of it see pdf below