Hello,

On 7 Nov, 02:20, nx7u wrote:
Francesco,
I have some better answers now, as I have a very complete BF981
datasheet in front of me.

Is it in electronic form? If so I'd be interested in it.

1. For fixed Vg1s and Vg2s, changing Vds has no effect on Id. Just
like you observed.
2. The *typical* Id for [Vg1s=0, Vg2s=+4, Vds=10V] is 11mA. The
minimum value of Id for the same bias point is 4mA. So your observed
7mA is within the process variation.
3. No the gates are not interchangable.
4. The datasheet does not give any Vg2s/Id curves, and Vg1s cannot be
positive (max gate current is exceeded nearly immediately) so you're
stuck with 7mA for this part.

hmm then I surely damaged the mosfet when playing with gates
reversed.
I better find another one.

5. Id *does* depends very strongly on Vg1s...for the typical part,
Vg1s=0V gives 11mA, but Vg1s=-0.5V gives Id=4mA.
6. Noise data is given at Vds=10V, Vg1s=0V, Vg2s=+4V: Fmin=0.6dB,
Gs,opt=0.6mmho, Bs,opt=-1.25mmho @ 100MHz.

Thanks for the informations, If I had seen the datasheet before I
wouldn't ever have swapped the gates.
Now looking for another mosfet :-)

73
Francesco IZ8DWF