FETS Needed
I have neither the facility or skill to perform the parametric testing described in these threads but what little I understand makes good reading. I'm trying to reduce the DC offset in my Hafler 9180 which uses 2SK163 and 2SJ74 fets in the front end. If I can get a good set of matched pairs I believe I'll reduce my offset to under 5mv so I can directly power a low excursion midrange driver. Can anyone tell me where I may purchase a few pairs of graded - matched devices (or appropriate substitutes) ? Thanks
I have neither the facility or skill to perform the parametric testing described in these threads but what little I understand makes good reading. I'm trying to reduce the DC offset in my Hafler 9180 which uses 2SK163 and 2SJ74 fets in the front end. If I can get a good set of matched pairs I believe I'll reduce my offset to under 5mv so I can directly power a low excursion midrange driver. Can anyone tell me where I may purchase a few pairs of graded - matched devices (or appropriate substitutes) ? Thanks
Please recommend sockets for testing these. I have searched Mouser and Digikey and the shelves of the local Electronics store and only found sockets that require the legs to be bent to fit. I have a socket that sort of works for the LSK170's but am having no luck with a socket for the LSK389's.
Thanks
Jim
Thanks
Jim
Sockets
I made my board using an 8 pin dip IC socket, and it works fine. If you use a quality socket (wil milled pins, not the bent/stamped ones) it works well. My design used both halves of the socket, in case the pins got lose on one side, you could use the other side. Since we used the test fixture in production, I wanted to make sure it lasted. The power and meter leads connect with alligator clips to 440 machine screws (1.5" long) as test posts. Came out nice....
I made my board using an 8 pin dip IC socket, and it works fine. If you use a quality socket (wil milled pins, not the bent/stamped ones) it works well. My design used both halves of the socket, in case the pins got lose on one side, you could use the other side. Since we used the test fixture in production, I wanted to make sure it lasted. The power and meter leads connect with alligator clips to 440 machine screws (1.5" long) as test posts. Came out nice....
Attachments
I also modified some IC sockets (the type with the gold
plate machined pins). Next plan is to build a multiple socket
tester to cover whole range of small sig Jfets to large mosfets
with TO-3 and also some type of socket for TO-220.
BTW, I have several of the Hitachi mosfets and know that
Hafler had some tester to match devices with. Does anybody
know what model that was and/or have schematic of Hafler's
tester?
plate machined pins). Next plan is to build a multiple socket
tester to cover whole range of small sig Jfets to large mosfets
with TO-3 and also some type of socket for TO-220.
BTW, I have several of the Hitachi mosfets and know that
Hafler had some tester to match devices with. Does anybody
know what model that was and/or have schematic of Hafler's
tester?
I think this topic is incomplete without some measurements
JFet matching and measured distortion - Part1
JFet matching and measured distortion - Part 2: LTP
Would be a pity if rare stuff like real measurements get lost in digital space.
Have fun, Hannes
JFet matching and measured distortion - Part1
JFet matching and measured distortion - Part 2: LTP
Would be a pity if rare stuff like real measurements get lost in digital space.
Have fun, Hannes
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.