KT120 load impedance and operating point?

[AudioGeek]

I am searching for output stage voltages and operating points. Specifically the KT120 SE UL and triode mode.

5K output, 400v plate to cathode, 40v bias, 100-130mA current?

Would a 300 ohm cathode resistor work? seen up to 500 ohm cathode resistors.

probably use a 400-0-400 power transformer.

or should i lower the current a bit?

 

[duncan2]

It can be run at 100ma - 400volts plate but you need to make sure its still 400 volts at that current for class A also remember its a higher heater current than the KT88 , this seems to be a big issue elsewhere .


Its not a tube I have come into contact with only the KT series up to 88.


I am sure some posters here will know more.

 

[waltube]

I think that the fixed bias is more funny to work with.
With 100 mA and 400 volt the point is fine and you get more power .
For triode mode the 5K can be little bit higher , the Rp is lower than 800 ohm so 3,5k can be good.

The 120 and 150 are two good tubes

Walter

 

[kodabmx]

Why not ditch the cathode resistor and use a TL783 as a current sink? Then you can have Dial-a-volt™ and run the tubes at whatever current level you like with the turn of a pot 🙂

 

[AudioGeek]

here is what i have 450v b+, 5k:8 opt, 100mA, 400vp, 41v cathode bias. heater current not an issue.

just wondering what others have for operating points.