TJ Full Music Carbon Plate 845 MKII is rated with 'nominal filament current - 0.6A at 10V' while the original RCA 845 tube was rated "filament current - 3.25A at 10V'. According to TJ Full Music's tube designer, for 845 tubes made with carbonized Thoriated Tungsten such as the RCA NOS 845 tube, filament current of 3.25A is required to generate sufficient electron emission for the tube to work properly. However, TJ Full Music's 845 MKII uses oxide coated filament which doesn't request as high as 3.25A filament current to generate sufficient electron emission.
TJ Full Music now makes a carbon plate 845 Mk3 (just released) that conforms to the Amperex/RCA standard. I have not heard this version.
TJ Full Music now makes a carbon plate 845 Mk3 (just released) that conforms to the Amperex/RCA standard. I have not heard this version.