Hi Steve,
In a power supply, likely the most important characteristics are dissipation
rating, on resistance (RDSon), drain-source breakdown voltage (Vdss), drain
current (Id), and package type. International Rectifier
(http://www.irf.com/) is a major player in HexFet devices, and has an online
selection guide. Start by finding the datasheet of the device you have.
Bryan

"Steve Lewinsky" wrote in message
. cable.rogers.com...
If I wanted to substitute a FET, what are the characteristics that are
critical for replacement? It is in a power circuit in a Monitor.