Re: uBitx V3 low power continues


Mark [et al],

Using a basic oscilloscope for measurements and a tone generator app for audio, each stage of the amp section seems to raise the RF level an appropriate amount. The exception to this is Q90, whose Collector output is lower than the Emitter input.  Maybe that's how that stage is meant to operate; the voltage measrements are about what the V4 troubleshooting guide says they should be.  Actually, all transistor voltage levels in the driver and PA stages are where they belong.

Regarding mike compression, that part works great as verified by an audio tracer and on the 'scope.  Even with tons of gain cranked up for the sake of following patterns through the circuit board, the peak-to-peak level only comes to about 2/3 of CW levels.  This dispairity is evident as early on as L1-L4.  My checks at Q20-Q22 are hard to read (by me at least).

That's where my hour of patience got me today.  I can try tomorrow to repeat some stuff, maybe/possibly get some pics if it's of any help.



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