In message , Gary
writes
Hi

Chris have downloaded PDF document for Exicon Mosfets and the pin out is the
dame as the Hitachi ones, so i have just tried another brand new set of
Exicon Mosfets and the same problem exists, the power meters are showing 20
watts of output, i listened on some headphones with gain on the headphones
turned down low and all i am getting is a raucous noise like instability, if
i put the original Hitachi Mosfets back in it works perfectly.
Hmm i wonder if these Exicon Mosfets are as universal as they claim they
are, maybe the amplifier i am using requires some sort of modification to it
so i can use them.

Thanks
Gary
"Chris Morriss" wrote in message
...
In message , Gary
writes
I tried replacing a set of Hitachi 2SJ-49/2SK134 mosfets with Exicon
MOSFET
Direct replacements from Maplins, i could not get them to work at all,
has
anyone else tried these replacements?

Gary



Check the pinout. The old Hitachi parts (as I remember) didn't use the
industry-standard pinout.

--
Chris Morriss


Does the amp use source-follower outputs? If so, you might be getting
RF oscillation of the output stage. This will really bugger things up.
I guess you don't have a 'scope so you can't check if this is happening.

You might be able to cure things by putting a 100 Ohms resistor in
series with the signal to the gate of each FET. Put the resistor right
up by the gate pin. This often cures this sort of problem.

The point of course is that the quiescent current is likely to be wrong
as a result of the threshold voltage and transconductance of the new
FETs being different from the old ones.
--
Chris Morriss