SteveH wrote:All,
Anyone running their MK3 in pentode mode ? I ordered an SDS cap board (but don't have it in my hands yet...) so I am not sure where I can get the voltage needed for the screen...Just am curious if anyone else pulled it off.
Thanks,
Steve
I do not know why you would wish to do this. Pentode mode has a higher output but more distortion than UL mode.
The easiest way is to tap off the B+ and drop the voltage with a resistor, but this is not advised. Screen supplies should be regulated. The screen supply should - if possible - have its own separate transformer winding.
Look at the screen supply in the above image. The B+ is dropped by a 10k/30W resistor then it goes through 2 diode tubes.