I haven’t looked up the specs, but assuming it is
an enhancement mode FET:
The tests you propose seem like a good starting point,
although there can be some quirks due to leakage in
the protective gate structures, or reverse biasing of
various junctions. I’d suggest grounding the gate to
the source when testing the drain-source resistance,
and you may need to have the meter probes
connected the proper direction (which with some
multimeters may be the reverse of the color coding).
Further suggestions:
Apply positive voltage to the gate, and you should
see the source-drain resistance drop. That tells you
that the gate isn’t open circuited, and the device
is capable of amplification. You might want to use
a pot to slowly increase the gate voltage, making
sure you don’t exceed the rated maximum voltage
even if one or your clipleads comes loose.
Beyond that you probably want some sort of fixture
for testing. Put a resistor in series between the
drain and your voltage source, then measure the
voltage across the resistor to check the drain
current. That limits the current to a safe value.
An LED or pilot lamp bulb will give a visual
indication of current flow.
Most important, however, is bypassing both gate
and drain to source while running DC tests. That
will help to keep the device from oscillating.
That bypassing needs to be effective over the
whole frequency range of the device. Otherwise,
a couple clip leads can turn it into a TGTP
oscillator pretty quickly, and the device can
self-destruct if you don’t limit the drain current
and gate voltage.
Many power devices are formed from multiple
devices connected in parallel internally. One
possible failure mode is if one or more of those
individual devices fails: the device may still
seem to work normally at low levels, but not
at full ratings. Or, it might be capable of rated
output at high drive levels, but with greater
distortion levels. For DC testing probably the
best test is to apply nominal gate voltage and
measure the current draw. That’s one of the
most difficult tests to do without the device
oscillating! At that point, you may be better
off trying to test it in the final equipment
instead.