The fellow I bought this amp from was not truthful about the condition...16 dead MOSFETs, blown diodes, resistors, etc... I'd love to get it back together but the Harris N-Ch RFM10N15, 150V DS, 10A, rds on 0.3Ohms and IR IRF9241, P-ch, about the same specs, are obsolete. These are TO-3 packages which makes substitutes harder to find , in addition, all 16 have to be well-matched as there are no Source ballast resistors used. Schematics below.
Looking on a couple of other forums I see lateral FETS like those from Exicon ECX10N20 & 10P20, or non-TO-3 MOSFETs like IRFP240 / 9240 (TO-247) suggested.
I am requesting help figuring out different biasing, and gate voltages, preferably with a TO-3 part.
I also need help with the minimum Source resistors I could get away with as Exicon has ceased making TO-3 packages and I would not be able to match them. They do have enough stock to cover the number needed.
Modifying the amp to accept TO-247 or TO-3P parts will be very difficult and unsightly.
There are claims that the no-resistor, all matched FETs are the source of "magic" in this amp, but I don't think I have much of a choice given the non-available MOSFETs.
Thanks in advance for any help!
Ivan
Looking on a couple of other forums I see lateral FETS like those from Exicon ECX10N20 & 10P20, or non-TO-3 MOSFETs like IRFP240 / 9240 (TO-247) suggested.
I am requesting help figuring out different biasing, and gate voltages, preferably with a TO-3 part.
I also need help with the minimum Source resistors I could get away with as Exicon has ceased making TO-3 packages and I would not be able to match them. They do have enough stock to cover the number needed.
Modifying the amp to accept TO-247 or TO-3P parts will be very difficult and unsightly.
There are claims that the no-resistor, all matched FETs are the source of "magic" in this amp, but I don't think I have much of a choice given the non-available MOSFETs.
Thanks in advance for any help!
Ivan
