Fluke 8060A JFET

[jdownj]

I am working on a few old Fluke 8060A meters.  I have already re-capped a few, and I have a few bad JFETs (Q1).  This is used as a series-pass regulator, driven by the MAC chip(U3).

The part number from the manual, Fluke 604678, replaced by 721936 only brings up one credible search result(Talon Electronics, 1 in stock but no price).  I need at least 2.  On the meters I have, the actual parts are marked with a clear Siliconix logo and "J2464" and "J2660."  I'm striking out completely to find a source, a datasheet, or a modern replacement.  Any help would be appreciated.

J

[dacman]

I would assume that SEL in the part description means that it is selected.  If I had to cross those, I would measure the Vg-cutoff voltage and also the saturated forward Ohms (D to S) with an ohmmeter and convert the value to transconductance.  I would then look for an N-channel TO-92 JFET with parameters that are in range (and hopefully get enough to select one that is a close match).  A J201 is the same type, but may not be a match.

[jdownj]

I did see the "Sel" notation with the 721936 part number in the new manual(From the Fluke site).  The older manual that matches my serial(I sourced from Artek) calls it 604678 with no mention of selected, even lists it as a manufacturer P/N of "J2464".  I think it really is a standard part... but your point is taken, measurement and guesswork may be the only way to obtain enough data to replace.

[vindoline]

 Don't believe that this is a critical part. I've replaced a blown Q1 with a jfet that I had on hand and the power rail came up fine. Sorry, I don't remember the specific jfet I used.

[retiredcaps]

drtaylor, who was part of the original 8060A team and a member here, but visits infrequently, could probably tell you.  See

https://www.eevblog.com/forum/testgear/old-fluke-multimeters/

[retiredcaps]

Answered here by Dave Taylor.

https://www.eevblog.com/forum/testgear/old-fluke-multimeters/msg1048360/#msg1048360