[Drake] TR7 PA problem: part 3

[ik2bcp - Guido Tedeschi]

Maybe, the problem seems to be in the finals, already substitued because it 
is a 2sc2879 pair.
Disconnecting the bases of both final transitors and measuring the output of 
drivers, across T2303 secondary, R2317 and C2306, the signal is regular with 
about the same amplitude across the HF frequency range, when loaded with a 
2,3OHM load to roughly emulate the transistors bases load.
When I reconnect the 2sc2879 bases, the driver frequency response returns 
wrong with 12dB difference between 1.8 and 18MHz.
I don't know what happened in the finals, it seems like the bases have 
increased their capacity to very high values.
With the bases not connected, the measurements with a multimeter of the 
junctions gives as result two healty transitors...
I'm now in a "cul de sac", before changing the PA transistors, has anyone an 
explanation of what happened?
Thanks and 73
Ciao
Guido, ik2bcp