[Amps] testing RF power MOSFET devices

[Dan Sawyer]

This is a general question regarding 'testing' RF power MOSFETs

1. There appears to be a difference between the MRF150 and the ST 
equivalent based on the 'simple' test of placing the negative lead of an 
Ohm meter on the source and the positive on the gate and then the drain. 
A set of 4 MRF devices show a steady low reading while a set of 4 ST 
devices discharge over a few seconds and the resistance rises. Is this 
significant?

2. Another pair of ST devices show a couple of meg Ohms resistance 
across drain and shorted gate-source. These devices perform well in a 
curve tracer, full voltage but limited current.

3. Is there a way to test a MOSFET at near full load with a curve 
tracer? (this would require temporary mounting of the device on a heat 
sink.)

Thanks - Dan