3fp7

[N2IXK]

Comparing the datasheets for the 2 tubes shows serious differences in deflection factors between the 2. The 3FP- is a less sensitive tube than the 3KP-, so you would need to increase deflection voltages applied to the plates to get the same size raster.

The horizontal sensitivity of the FP is 221 Volts per inch, compared to around 115 Volts per inch for the KP. Vertical sensitivity is 163 Volts per inch for the FP, and around 85 Volts per inch for the KP.