F5T all good, on mini transformer just to test. thought it was a good idea now to wack in big PSU 🙂
I trimmed the bias in my F5Tv2 up to 400mV across 0R5, oh man, how much flame and smoke this amp can produce! I guess, Nelson was right about a fire extinguisher 🙂 For guys who are new in amp building be careful and let the amp heat up before adjusting bias high 🙂
MOSFETS and most sadly the board(forgot the word — contact plates around holes). Feel myself so stupid! :-(
No, diodes are out of the main think, but no heat thinks on them,but they are cold 🙂. I will try again tonight-tomorrow.
Listen to uncle Buzz, he knows the stuff 🙂. Only it happened in seconds: oscillations for a half a sec with increasing amplitude and then just up!
Possible you had just one start to go. Possible you had oscillation, but since it has been playing for some time, i tend to think differently. As I remember, you had one biasing higher than the others. Was this the one that went first?
It is the same channel yes. However, I cascoded FE(1/2.2 of rail). I have to say, that after cascoding the amp became much more sensitive to turns of the trimpots. Do you think the cascode could cause th oscillations? But I tried it with 24V PSU and it worked.
It is possible, but the cascodes could have increased the bandwidth of the amp enough to create possiblity of oscillations. I would think you would have seen evidence of it in burned gate resistors, but i guess it could have been small enough to trigger burn. Perhaps ZM or someone has another perspective or opinion. For now, I suspect, too high a bias on startup and it just got away from you.