5f4 cathode voltage

[scole]

how do you measure the cathode voltage on a stock 5f4? across the 6k8 or the 56k or across both the 56k, 6k8 and the diode?

[Paul P]

scole,

The 5f4 Super uses fixed bias so the cathode is grounded. You probably
mean "bias" voltage ? It's measured to ground, as are all voltages as stated
at the top of the schematic, so any ground should be fine. Or across the
56K if you want.

Paul P