[BULK] - [Amps] IC-718 and AL-811: Icom manual misleading, in terface nec...

[Japerlick at aol.com]

Actually, this is quite common in transistor switching applications.  
Transistors (whether FETs, Bipolars, IGBT's whatever) have have "Safe Operating 
Areas" which is a technical term for the range of simultaneous voltage and current 
levels it can safely sustain.  

For example, the venerable 2N2222A is rated at 75 Volts VCBO, 40 Volts VCEO 
and 0.6A max Collector Current...but the max power dissipation is 0.5 watts.  
Obviously you cannot sustain 75V at 0.6A SIMULTANEOUSLY.   Manufacturers 
specify a safe operating area--usually in chart form--showing how much current the 
transistor can pass for given voltage conditions--both in forward and reverse 
bias conditions.  It's important to note that these charts do not necessarily 
correspond to a simple curve of the maximum power dissipation.  

Combined with safe operating areas is the consideration of junction 
temperature.  Almost all of these specs are given for device junctions at 25 degrees C 
(about room temperature).  Of course, you can imagine, the ratings degrade at 
higher temperatures.  Overtemperature and overvoltage are the two most common 
transistor-killers.

So, yeah, the Alpha guy is probably right...you can't get both max voltage 
and max current simultaneously....and it is not that simple.