[Collins] 4CX250 vs. 4X250

[Ray, W2EC]

In general this is true.

If you are looking specifically at the KWS-1 however, there is a Service
Bulletin (SB-5A) that discusses a series of changes made to the 10 meter
Driver Tank coil recommended due to the slightly differing input
capacitance between the original 4X150, the follow-on 4X250 and the
final 4CX250. So while the tubes can be swapped and used, you may find
you need to apply SB-5A to a KWS-1 for correct 10 meter performance.

73, Ray  W2EC

PS, I can't include Jerry's comments because it is copyrighted and I
don't have Jerry's permission to reproduce it.