Nederlands Transistorforum - Biasing the 2N3819

Biasing the 2N3819 (reply)

Maurice — Wed, 05 Nov 2025 21:27:01 +0000

Agree with Maarten, probably something wrong with the 2N3819.

There are many simple schematics Af amplifier to be found with this FET.
Try those with exact config of components.
If that fails, you know your FET has problems.

Biasing the 2N3819 (reply)

Maarten Bakker — Wed, 05 Nov 2025 15:46:12 +0000

Maybe your FET is a fake or out of spec surplus part?

In any case, it would be more useful to post your schematic, as that is unique while people can find a datasheet by themselves.

Biasing the 2N3819

Jordan22xx — Wed, 05 Nov 2025 12:01:35 +0000

Hey all,

I’m working on a small DIY audio preamp and decided to use the 2N3819 J-FET (datasheet: Kasuo link
) for its low-noise characteristics. It’s supposed to give a nice clean boost, but I’m running into some issues with biasing, the gain feels off and there’s more noise than I expected.

I’ve tried a few resistor combinations, but the bias current still seems low. Maybe it’s something with my layout or nearby power traces?

Has anyone here used the 2N3819 for audio input stages before? Any advice on biasing or grounding to keep the noise down would be a huge help.