the only I worked with was on my FADA (rca 630ts clone) and had a 12 inch screen 12LP4, which needed a bit stronger magnetic field vs the 10 inch 110ma vs 100.
otherwise , the circuit was almost the same as below, except for having a PM ion trap, and having that circuit omitted.
http://www.qrp.gr/technology/vttv/rca630ts.pdf
i still have the PM focus magnet of of a necked 21ep4b, but at almost 120ma equivalent,it's no doubt way too strong to use on the CRT you have,
you never DID say what that was...