[Jim - G4MEZ]

Had another look at the amp yesterday... The driver boards are faultless. Swapping them proves the problem is with the output transistors and/or their temperature compensation diodes...

I checked both pairs of output transistors and diodes for leakage and can find none at all. One diode on the problematic channel has a slightly higher forward resistance but that's all...

Again, long soak testing at moderate volumes and power outputs reveal no problems...

I note that the setting of the quiescent currents are very temperature dependant... Checking this morning in a very cold workshop the current is a lot less that it was yesterday afternoon in rather warmer ambient temperatures...


Mr. Leak does not say at what temperature the currents should be set. Any thoughts? 20 degrees perhaps?

Won't get a lot done today; I'm off running a half marathon later...