LND150 as a replacement in Cathodyne PI?

[Draal]

I need some guidance in utilizing the LND150 mosfet as the phase inverter in my cathode biased Harvard style amp. My B+ is around 300v. I love tubes but I am open to experiment as I have a few of these in my parts bin.

[pdf64]

Good idea!
The absolute max gate to source voltage is listed as +/-20V.
A series reversed pair of 12V zeners might be used to ensure that.
https://ww1.microchip.com/downloads/en/ ... 041114.pdf

[pompeiisneaks]

Here's a good thread on DIY Audio about it:

https://www.diyaudio.com/community/thre ... ne.290344/

Especially see the post #6 by tubelab_com

Edit: somehow hit submit on accident mid post.

~Phil

[Ten Over]

I need some guidance in utilizing the LND150 mosfet as the phase inverter in my cathode biased Harvard style amp. My B+ is around 300v. I love tubes but I am open to experiment as I have a few of these in my parts bin.

Here are a couple of them at 350V. I can re-design these for 300V and 220k grid leaks if you're actually interested.

Cathodyne LND150 #1.png

Cathodyne LND150 #2.png

[Ten Over]

This is always handy when working with LND150

LND150 Average Characteristics.JPG

[pdf64]

Does the gate draw current at any point, ie akin to a forward biased grid?

[Draal]

I need some guidance in utilizing the LND150 mosfet as the phase inverter in my cathode biased Harvard style amp. My B+ is around 300v. I love tubes but I am open to experiment as I have a few of these in my parts bin.

Here are a couple of them at 350V. I can re-design these for 300V and 220k grid leaks if you're actually interested.
Cathodyne LND150 #1.png
Cathodyne LND150 #2.png

Definitely interested!

[Ten Over]

Does the gate draw current at any point, ie akin to a forward biased grid?

Nope. But the zeners will.

[Ten Over]

Here is one for 300V and 220k grid leaks. Swings 60Vp in both directions, draws 1.18mA.

Cathodyne LND150 Draal.png

[Draal]

Here is one for 300V and 220k grid leaks. Swings 60Vp in both directions, draws 1.18mA.
Cathodyne LND150 Draal.png

Thanks Ten Over - just what I was looking for!

[TUBEDUDE]

Please post your impressions of the changes in response, tone etc. Some pre and post clips might help you if the changes are subtle. Good luck!