Quote:
Originally Posted by Chris K
OK I saw in the introduction thread that what I described above is the focus coil. I have attached a picture from a later model restored on Phil's Old Radios website. What's in the frame behind the yoke is what I described. I surmise what's on the ground behind the chassis is the ion trap and it's electromagnetic. My 721 does not have that. It just has a metal band and I don't think it's magnetic in any way. I just looked at Bob Anderson's restoration on this site and his also has the electromagnet. Oy veh!!! Can an ion trap be just a passive metal band with symmetrical projections coming off of it?
|
Yes behind that set is the EM ion trap (brown cylinders) and the CRT socket (black cylinder).
There were several styles of PM ion trap. The oldest 2 common ones (double ion trap style) were a black cylinder with 2 different sized magnet rings (same one in shangos Philco 48-1001 series), and a rectangle magnet with 2 bands that wrap around the neck (the one closest to the screen was typically blue the other black). There were also various single ion traps usually with a rectangular magnet and a single around the neck band.