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I too had some trouble getting external VFO sigs through to the mixer.?? I suspected a bad Q9, but turned out that the transistor was good. (Check the voltages without the Raduino connected.)?? You might have to remove C91 and/or C92.?? On my 40 meter rig, with an analog VFO running at around 5 MHz, I had to remove C91 to get sufficient signal through to the mixer.? On my 60 meter BITX, with an Si5351 running at around 17 MHz, I removed BOTH C91 and C92.?? 73? Bill? N2CQR


On Tuesday, March 21, 2017 12:29 AM, Raj vu2zap <vu2zap@...> wrote:


IF Q9 is bad some RF from Raduino will get through to the next transistor and RX will work.

I had a 1K open in the 3rd VFO stage and 3904 blown!

Raj, vu2zap

At 21/03/2017, you wrote:

Hi Roy

I had a problem of the Si5351 getting to the mixer. Turned out my Q9 was shot. I happened to have some on hand.

73

Ken VA3ABN

On Mon, Mar 20, 2017 at 6:51 PM, Roy Appleton < twelveoclockhigh@...> wrote:

Finally got back to troubleshooting my BITX40 transmitter failure. Using Randy K7AGE voltage chart, the only stage that had bad DC voltages was Q9, with just a few milivolts on the base, emitter and collector. What I don't understand is that Q9 is used in both transmit and receive and yet my BITX40 receiver seems to be working.

Any thoughts, and also any suggestions on how to "test" Q9?

Thanks,

Roy

WA0YMH