EA Trem---questions

[sta63bmx]

While we're talking about transistors and pinouts, how do you check MOSFETs and JFETs?  For bipolars, I just plug them into the hFE thing on my cheapo Craftsman DMM.  But does that work with FETs?  Please correct me if this is wrong, but I think that on an n-channel FET, you should see this...(using the diode setting, the first pin listed is the positive probe on the DMM)

From gate to source, one diode drop (silicon style, right?  About 0.6V?)

From source to gate, open circuit

From drain to gate, one diode drop

From gate to drain...?  Open circuit?

From drain to source, two diode drops

From source to drain...?  Open circuit?

I just use them. 

[Transmogrifox]

While we're talking about transistors and pinouts, how do you check MOSFETs and JFETs?  For bipolars, I just plug them into the hFE thing on my cheapo Craftsman DMM.  But does that work with FETs?  Please correct me if this is wrong, but I think that on an n-channel FET, you should see this...(using the diode setting, the first pin listed is the positive probe on the DMM)

From gate to source, one diode drop (silicon style, right?  About 0.6V?)

From source to gate, open circuit

From drain to gate, one diode drop

From gate to drain...?  Open circuit?

From drain to source, two diode drops

From source to drain...?  Open circuit?

I just use them. 

For a MOSFET, the diode tester isn't very helpful.

For an N-Channel JFET, here's what you should see:
Gate to source: one diode drop
Gate to drain: one diode drop

In a JFET the drain is the source and the source is the drain.  There's no difference (unless you have a type with something else built in for some means of protection)

Drain to Source (or Source to Drain) is unknown.  The gate is at some floating potential, so you're measuring across the N-channel that is conductive to whatever degree may be allowed by the static charge stored on the gate.  Therefore, this test would not be conclusive of anything unless it beeped like it was a real low resistance...like something was fused inside the FET so that there was a short circuit from drain to source.

Measuring backward from source to gate/drain to gate should give you an open circuit reading.

I have found MOSFETs and some JFETs to be very sensitive to high solder temperatures and ESD.  BJT's in my experience have been very rugged.

[sta63bmx]

Cool.  Thanks for the info!