2N5484 JFET

The 2N5484 JFET is best known for the Randall RG100 preamp. It’s also a close substitute for the type used in the Echoplex EP-3 preamp. However, it has been discontinued in through-hole format for many years and old-stock parts are difficult to find.

These are genuine MMBF5484 (SMD equivalent) parts from ON Semiconductor that have been pre-soldered onto an adapter so they can be used in through-hole layouts. Nearly all of them are within the Vgs(off) range of -1V to -1.5V (average: -1.33V) and will perform exactly the same as the through-hole 2N5485. They also have a blank white screenprint on the reverse side so that you can write in the Vgs(off) value, for example if you need to match them for a specific application.

You’ll have to solder in the legs yourself (clipped leads from resistors or diodes work great). The JFETs are panelized, so they will need to be manually broken apart and tabs removed before use.

Note: Per the datasheet, the source (S) and drain (D) pins are interchangeable and can be used in either direction. Cheap component testers will sometimes show the D and S reversed from the silkscreen, but a Peak DCA75 will correctly label them as interchangeable.