j201 question
- Thread starter swelchy
- Start date
spi
Well-known member
I had a bunch of way out spec 2n5457s from them last year. I never bothered to try to contact him, so I don't know how responsive he is about it. And I've found places where I can use these out-of-spec jfets (in buffers, etc.)
One thing to try is build a buffer with your bad ones and see if they buff. Do you have a breadboard? Or try the ROG measurements on them and see if they work as jfets.
One thing to try is build a buffer with your bad ones and see if they buff. Do you have a breadboard? Or try the ROG measurements on them and see if they work as jfets.
Cybercow
Well-known member
Just now saw this post.
It's NOT a failed measurement. I've purchased hundreds of J201s from GuitarPCB and even this some of them test as 2 diode junctions with the DCA75 Pro, they are still good.
As with all JFETs, they are symmetrical (Drain & Source are interchangeable) and I've found that when that symmetry is perfect, it can fool even the DCA75.
To prove it, I used sockets in my builds and tried the ones that tested as 2 diode junctions. They still worked a treat.
Barry, at GuitarPCB is a lone operator and crazy busy. Best to contact him thru his forum.
It's NOT a failed measurement. I've purchased hundreds of J201s from GuitarPCB and even this some of them test as 2 diode junctions with the DCA75 Pro, they are still good.
As with all JFETs, they are symmetrical (Drain & Source are interchangeable) and I've found that when that symmetry is perfect, it can fool even the DCA75.
To prove it, I used sockets in my builds and tried the ones that tested as 2 diode junctions. They still worked a treat.
Barry, at GuitarPCB is a lone operator and crazy busy. Best to contact him thru his forum.
swelchy
Well-known member
Hmmmm…. maybe I spoke too soon? I guess I better throw them in one of my chop shop builds and give them a bias to see if they indeed are fine… I set them aside and labelled them just in case the tool was reading then weird. Thank you for the heads up and I may learn something from it…going to test them in a build later tonight to see.
Cybercow
Well-known member
That's exactly what I did with my first go-around with that DCA75 measurement result. Then I got curious and tested them anyway.
Looking forward to your results. Whatcha building?
swelchy
Well-known member
haa... I have about 30 different builds in progress... You mean what are you going to actually finish... I have a couple chop shops I can use to test the jfets because they have sockets already there.
Cybercow
Well-known member
In my experience with buying hundreds of J201s from GuitarPCB, not one has been bad. I eventually hand tested every one of them with my DCA75. And those that red as 2 diode junctions actually worked when applied in a working circuit.
But for the sake of having an excellent piece of test gear, I highly recommend the DCA75 over the DCA55 because it shows more data about the tested device than the DCA55. The DCA75 also comes with Windows software for obtaining trace curves on BJTs, FETs, diodes, LEDs and other devices. (see attached image for some traces ran on two different JFETs)
Ok I’ll plan to get one. Are they quite a bit more expensive than the DCA55?
Digikey says they have some supply issues on the DCA75.
