SE EL34 design

[Groover]

What are the variables I need to consider to convert a SE 6V6 design (cathode biased) to use an EL34 instead.

Things that come to mind are: What are target values for available B+ voltage, OT primary impedance, OT current handling capacity.

What else do I need to consider?

[MWJB]

PT 6.3VAC heater winding needs to be at least 2A, preferably a little more.

Plate voltage to ground might be 400-450vdc.

OT Pri 2.5K-5K. 70mA current handling, though you probably won't be running it that hot at the higher B+.

Pins 1&8 must be tied together, you could add 1K 5W screen grid resistor if you like, as well as a grid stopper (1.5-5.6K).

10W Cathode resistor, 470ohms for B+ up to and around 400vdc, 680-800ohms if higher.

100v cathode bypass cap.

[TheTinMan]

You might want to look through some of the single-ended designs on the AX84 forum. For whatever reason, EL-34s don't seem to be their favorite power tube but many of the schematics show alternatvie specs for that tube.

HTH

Chip

[kldguitar]

if you want simple only connect 1 pin to 8pin

If you want simple you can connect 1 pin of 6l6 with 8 pin.
do not change others.

[scole]

heres a cool design that will run just about any tube you want

[Groover]

Scole, do you have that in schematic form, or a more contrasty, sharp version of the layout?

[ThermionicScott]

Mullard/Philip's recommended operation, if it helps:

265V B+, -13.5V grid, into a 2kΩ load for 11W at 10% THD. For cathode-bias, just use a 120Ω/5W resistor.

Just for fun, I whipped up a load line pretty close to that spec:


- Scott