21CBP4A in place of 21WP4X??

[bgadow]

The one book I checked says the 21WP4 has no subs. (aside from suffixes, A, B,etc) The GE Essential Characteristics book lists differences as being: CBP is electrostatic focus vs. magnetic on the WP4, & the WP4 is listed as having "dimensions different from normal". There are some other differences but those are the major ones I see. I think the CBP was fairly popular? I have a pair of Motorola's that use it, from 59/60. One has a weak crt but I have a NOS rebuilt in the attic waiting.