Re: #bitx40 Q8/Q9 dead - no TX or RX #bitx40


Jerry Gaffke
 

Actually, not much need to remove Q7,Q9,Q9 if doing the quick fix.

Remove R70, short across C71 to ground T2-1,
cut the trace from Q7 to T2-6,
then add Farhan's 4 resistor network between Raduino and T2-6.

Removing 12v from the LM78L09 at U2 might save a few milliamps.



But again, you may have a bunch of other issues to chase once this is cleared up.


Evan is right, a grounded DDS1 would give the symptoms you describe.
Base goes to ground, and so does everything else around Q8 and Q9.
But DDS1 has a series cap on the Raduino, so a short on the DDS1 signal
would almost have to be a problem with the DDS1 wiring harness.

Jerry



On Thu, Sep 17, 2020 at 07:00 PM, Jerry Gaffke wrote:
A possible quick fix:  remove Q7, Q8, Q9.
Drive the mixer exactly as Farhan now does in the uBitx with a 4 resistor network at the transformer.
The only reason Q7,Q8,Q9 are in there is because the Bitx40 used to have an analog VFO.

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