A low impedance source might be able to provide enough grid current for the ECC83. Alternatively, is this 'measurement' actually a simulation using valve models which omit grid current or perhaps naively assume that grid current starts from Vgk=0V?
Spice model for ECC83 tube is this:
******************
.SUBCKT ECC83 1 2 3
*ANODE G CAT
X1 1 2 3 TRIO2 G=1.02m MU=90.6 B=18 Vc=50.7 k=5
X2 2 3 Igrid ALPHA=.01m BETA=.1U
C1 1 2 1.7p
C2 2 3 1.6p
C3 1 3 .46p
RF1 1 3 200MEG
RF2 2 3 50MEG
.ENDS
******************
Sorry, as I am not a Spice model expert that doesn't tell me much. It appears to include grid current, but how accurately I don't know. I suspect it will not model the grid current which can appear from about -1V upwards.
Incidentally, can we limit the word 'measurement' to mean actually measuring something? You know, with a real meter or real 'scope on a real circuit; not virtual instruments in Spiceworld.
Incidentally, can we limit the word 'measurement' to mean actually measuring something? You know, with a real meter or real 'scope on a real circuit; not virtual instruments in Spiceworld.
I know you're right and I understood from the beginning what you mean. I just wanted to analyze how this amplifier just pure curiosity.
Finding another PSF for ECC83, raising the voltage to + 550V, performances have improved radically.
Thanks and I hope I have not upset anyone!
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