01 July 2016

Bad IV-27M VFD

IV-27M on its datasheet.
I bought this IV-27M NOS VFD display at Ham Radio Friedrichshafen 2016 flea market for 5€. The seller had three pieces and I took one. Its date code is 91XX.
When I came home I dug a datasheet looking mainly for the filament pins, so that I could test the display for good. Then with the DVM I kept looking for continuity (a low resistance value, few tens of ohms) but nothing was found.
I spent the next ten minutes looking into through the glass, trying to see the thin filament and where it should go to pins 1&2, just to discover that the connection between pins and filament is missing. Now I am the unhappy owner of a cold-war era leftover.

Lesson learned: do bring a DVM and do use it!

This display does not have a thoriated tungsten filament, it does not emit weak radiations, so that it cannot be reused as a test source. It will remain a warning reminder with a 5€ price tag.

Can you spot the filament ends in there?
The same seller had both new (5€/pc) and used (3€/pc) red-coated Nixies I forgot the model, that I haven't bought because I don't like red ones. Now I am thinking that used tubes (you can tell if they were cut out from PCB) might even be more reliable than new ones, that could have been once discarded but then followed a different route than the trashbin.