SOT-23 test sockets and measuring JFETs

owlexifry

Well-known member
so after all the lurking I've done here - it has been thoroughly burned into my brain that JFETs are not simply plug and play and shouldn't be considered as such.

my first attempt to measure JFETs for a phase 90 build went well.
simply built the RG Keen 'greatly improved JFET matcher' on vero and it works a charm. gives Idss and Vp values. nice.

my initial experience with JFET based circuits for distortion did not go well. one of my first builds was one of those dr boogie things. it worked fine, but it left a lot to be desired. admittedly, i had no idea what i was doing back then, and i was super excited about getting into the whole amp-in-a-box thing, but sadly it skewed my perception of what I think JFET distortions are capable of, and I hadn't really bothered since.

but reading some of chuck bones graveyard articles on the matter of JFETs gives me hope. I want to believe.
could it really be that my negative experiences with JFET distortions are attributed to poor JFET selection/improper JFET specs? Well that's the message I'm getting, I've taken the word for it, and went ahead and ordered some MMBF5457 & MMBFJ201.

with a renewed optimism, i'm keen again to try a few circuits (figment, blue shoe, mofeta, golden falk etc.)
but i don’t wanna half arse this, i want to do the circuits justice and take the time to select appropriate JFETs.

so last night I made an attempt to test these tiny fellas (without soldering), and tried to use a SOT-23 adaptor board socketed to the RG Keen JFET matcher.
after a while of persistence, I was able to get readings, but honestly this was just stupid, and painfully difficult to get it to work.

I really don't want to use adaptor boards when there's SOT-23 pads available on the PCB, so my question is - how to test SOT-23 JFETs without soldering them to a board?

is there some sort of a socket available that people are using?

i see two options:
Peak23 SOT23 socket

ebay SOT23 socket

I would greatly appreciate some recommendations :)
 
I think you found all available commercial socket types (Peak and sot23 programmer adapters). I've searched several times and the results are similar each time.

You could try something like an in-circuit programming/testing device. Three movable pins on posts (tightened with rubber bands, for example). Probably not very convenient to use and easy to send the transistor to another dimension...

Maybe this will give you an idea.
There are also test clips available, but they would have to be modified
1705644802646.jpeg
 
I think you found all available commercial socket types (Peak and sot23 programmer adapters). I've searched several times and the results are similar each time.

You could try something like an in-circuit programming/testing device. Three movable pins on posts (tightened with rubber bands, for example). Probably not very convenient to use and easy to send the transistor to another dimension...

Maybe this will give you an idea.
There are also test clips available, but they would have to be modified
View attachment 66311
many thanks for the tips and input!

that smt launcher looks interesting..

but i guess i might just be better off with one of those peak23 adaptor socket thingys
 
Here's something I just cooked.

Programming clip, pogo pins, piece of cardboard foam with a dent for the transistor.
White foam slides in and out for easy transistor replacement.


1707150832941.png


1707150872071.png

1707150882108.png
 
Posting here in case someone finds an affordable source(you can get a pair for $52 on Ali but that's more than the peak jig)
The sot23 clamp used in the Peak jig PN is 499-P36-20
I did find them here for $23.50/$36 shipped conus as well.
 
Posting here in case someone finds an affordable source(you can get a pair for $52 on Ali but that's more than the peak jig)
The sot23 clamp used in the Peak jig PN is 499-P36-20
I did find them here for $23.50/$36 shipped conus as well.
Mouser caries the P35 for $13 but no P36 😭
 
Back
Top