How can you conduct a simple test for a MOSFET?
About the only thing you can test with a mulitmeter is the gross state of the gate. Measuring from the gate to the source should give you essentially open circuit. Actually, it will look like a capacitor in the 1000 pf to 10000 pf range. If it looks like a low-value resistor you know that the gate is blown and you can discard the FET.

To test anything else you need a circuit, but that circuit can be very simple. For instance, a decent overall tester might be







simulate this circuit &ndash; Schematic created using CircuitLab

When the switch is open the LED should be off, and when the switch is closed the LED should be on. Almost any LED will work (although you should avoid IR LEDs - they are a bit hard to see). To be safe, 12 volts is better than 5. Some FETs won't work well in this circuit with only 5 volts on the gate, but many will do OK.

This circuit will test the basic functionality of most n-type FETs in switch mode, which is the most common use these days. It is not appropriate for RF FETS, but I doubt you're interested - if you are doing RF amps with only a multimeter as instrumentation you're doomed anyways.