But then they don't take the LM317 "undocumented feature"
Has anyone else other than I, tried using LM317 CCS on the EL84 cathodes? Actually, that is kinda misleading, I tried it on a 6S4-modified Rev D. (25 mA @ 325VDC B+) Still have to work out a couple resistor valuechanges in the VA/PI section to make it 100% right...
More mod-madness, for those who dare....
Got lots of 6GK6s, (or 10/16GK6s) ?
Another mod I haven't yet tried, but it should work for 6GK6s. This method requires a bit of etch surgery around each EL84:
Cut the etch between each EL84's pin 9 and the UL tap on the terminal board.
Connect/jumper pin 8 to the UL tap.
Connect pins 1, 3, and 9 together (this connects the cathode to G3).
Don't like butchering the board ?
Alternate, no-etch-cutting procedure, for a new build:
Cut or bend pin 9 on each of the EL84 PC board tube sockets, so that it doesn't make contact with the pin 9 pad on the board.
Jumper pins 8 and 9 on the board, then install the socket(s).
Jumper pins 1 and 3 on the bottom side of the board - pin 9 isn't really necessary, as it is a duplicate connection, or if you bent the pin, then it could be connected to pins 1&3.. This connectrs the 6GK6's G2 to pin 9, so the PC board doesn't require any surgery, and additionally connects G3 and Cathode.
All I need is to get ahold of a virgin rev C or D board and give it a whirl...