Quick question here - I have a circuit that originally used a 2SK30ATM-GR JFET, with an RDS(on) maximum of 800 ohms. Most of the cheap JFETs I can find have a significantly smaller RDS value, generally below 5 ohms. The application for this JFET is just an audio circuit, so is the RDS value going to affect anything if I substitute in a new JFET?

  • \$\begingroup\$ Are you sure you're looking at JFETs? usually they don't quote an RDS(on) for JFETs. That is for enhancement mode MOSFETs. Idss is a common parameter for JFETs. What devices have you looked at? \$\endgroup\$ Oct 10, 2020 at 1:37
  • \$\begingroup\$ Maybe I just have a bad datasheet for the 2SK30 - the site below states RDS was 800 ohms max. So basically any JFET that meets power ratings will work? \$\endgroup\$
    – zvolk4
    Oct 10, 2020 at 2:21
  • \$\begingroup\$ alltransistors.com/mosfet/transistor.php?transistor=14782 \$\endgroup\$
    – zvolk4
    Oct 10, 2020 at 2:21
  • \$\begingroup\$ It depends entirely on the circuit it is used in. \$\endgroup\$
    – Andy aka
    Oct 10, 2020 at 7:47
  • \$\begingroup\$ @zvolk4 - The term RDS is not used in the datasheet itself, only in the preamble at the top. That part even calls it a MOSFET whereas the 2SK30 is a JFET. RDS is not aterm used to compare JFETs. Please give an example of on of the cheap devices you are comparing. \$\endgroup\$ Oct 10, 2020 at 8:50


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