Sean,

Placing the load between the +12v and the drain, and putting the source
to ground, worked.  Thank you VERY much.

Jim
wb8zbd

Sean Breheny wrote:
>
> Hi Jim,
>
> First off, I would place the load between the +12V and the drain if at all
> possible,then ground the source. As you have it,it will act a bit like a
> source follower, the source voltage will be close to the gate,which is as
> you describe. The problem is that you need as close to 5V from gate to
> source as possible. Initially,the source is a zero volts and applying 5V to
> the gate causes 5volts from gate to source and you get conduction.
> However,as the voltage across the load rises because current is now flowing
> thru it, the source voltage comes up higher closer to the gate and the Vgs
> gets lower,hence less current. Equilibrium is reached when the source is
> only a small offset from the gate.
>
> Sean