BF245A real or fake?

[spoontex]

Hello,

I bought some BF245A from Germany, ebay seller. How can I check if it's a real o fake part?




I've seen some circuit to measure idss and VP.





I can use this?

Thanks.

[Rob Strand]

The first thing to do would be to check the pinouts as the BF245A has a different pinout to the common JFETs



You can use a DMM to identify the JFET pins, as described here,
https://www.diystompboxes.com/smfforum/index.php?topic=128553.msg1238801#msg1238801

After that yes use that jig to measure the parameters and compare them against the datasheet.
(See here for a few jig refinements,
https://www.diystompboxes.com/smfforum/index.php?topic=129436.0)

If the pinouts or parameters don't match then clearly they can't be BF245A's.
If it's just a pin out difference then you can identify the pins, find the parameters,
then decide if the parameters are close to a BF245A.    That means they aren't
BF245A's but it is likely you can still use them (you will need to swap the pins
on the PCB).

updated MOSFETs
https://www.diystompboxes.com/smfforum/index.php?topic=129497.0

[spoontex]

The pinout matches and the parameters more or less the same ( +-50mv ) as described in the datasheet. So, I think that this BF245A are real jfet.

Thanks.