[Phil Allison[_3_]]

"patrick-turner"


Well, with 10:1 probe, presumably you have 2.6Vrms at 6SN7 grid.


** No, the 10:1 probe was used merely so I did not load the signal at the
300B socket grids.


If the 6SN7 gain is say 17, then its drive to output tubes is 44.2Vrms, ie,
62.5Vpk, or getting close to the dc bias voltage for 300B.


** Wrong again.

The two halves of the 6SN7 are direct coupled, so 260mV input becomes 74 V
rms ( 200V p-p) at the 300B grid pins.



..... Phil