Thanks everyone for the discussion, much appreciated.
I did find a typo in my measurements documentation. The base is 2.9 v not 3.9. That resolves the concern with QD1.
Using a fluke 8062 to measure. It has been reliable for years and I checked it against my Simpson 260.?
?
I have removed from circuit.?
CD28
LD6
CD29
CD27
RD15
QD1
There should be 11.9 volts at? open end of RD21, and I'm still only getting 2.1 v.?
I have removed RD 21 and verified 10K Ohms and reinstalled. I'm now looking for a solder bridge, lifted pad or some other PCB issue.
?
May just bypass this mic preamp and use an external one that I know works. Spent too much time on this.... especially since I will probably use the sBitx for FT8/POTA most of the time.
?
Will update you with next findings.....
?
73,
?
WF4RC-Rob
