[NLRS] FET amp question

[Glen Overby]

Last fall I purchased a 30W amplifier kit for 1296 from K6QPV.  It uses an
Infineon / Ericsson PTF 10021 MOSFET.  I carefully assembled the kit, and
mounted the FET on a large heatsink.  I brought the device up carefully -
first I powered it up at 12v and set the bias current.  Then I increased the
voltage in steps while watching the quiescent bias current (this was the
proceedure recommended by the kit instructions).  I had a 1/2 amp fuse inline
just incase I made a mistake (I increased that to 1A now).  I calculate that
the device should draw 2.5 - 3A at full power.

I'm monitoring the current draw and the RF power out.  At 24 volts, it draws
about .7A with about 1.5 - 2 watts input.  The output is also about the same,
that is: no gain.  I measured both the input and output power with a Diwa
CN-801 power/swr meter, with the output into a dummy load.

My question is this: what is the characteristic of a failed FET?  If I somehow
destroyed the device is this how I would expect it to behave?

I'd appreciate any other ideas about why the part doesn't appear to amplify,
or what to look for.

Thanks,
Glen, kc0iyt