Couple of FET questions

[Luthierwnc]

Hi guys,

I'm working up a 100k build and will be adding the FET circuit for the first time. Most schematics I've seen have the 10k resistor going through a 5uf cap and to the trimmer, the other side of which is grounded. On others I've seen, there is an 8k2 bleed resistor coming after the 150k supply. Opinions? I figure I'd leave room on the board.

The other question is whether to use electrolytics or tantalums. I don't have a dog in the fight but am curious who likes what.

For extra credit, this is the switch I was planning on using in place of the shorting jack -- but I don't know if it is better to have a jack you can't possibly screw up or a switch so you don't have to unplug. If there is a smarter way to do this, I wouldn't be surprised.

Thanks and cheers, Skip

[Structo]

I recently installed a FET board in my 100w ODS clone.

I used the pcb board from AGB amplifiers (jborders) to make it easy.

The critical thing as far as I know is to have 10v at the Drain.
Adjust the Source resistor to achieve that.

Then you should have 20v at the junction of the 10K and 150K resistor.

Adjust the 8.2K resistor for that.

What I did was install some leads into the pcb and put two pots on them to adjust it until I had both voltages where they should be.
Then I measured the pots and installed fixed resistors with those values.

I used electrolytics and as per some notes I took I installed a 470pf input filter to flatten the response and I also used a 25uf bypass cap for a fuller tone.

I wired it according to the #124 layout using the Switchcraft jack and it works fine like that.

Good luck.
So I can't advise on the switch setup.