While the BITX is not built in modular fashon, you can test it as if it were modules.?
From the volume potentiometer to speaker can be regarded as a module, and tested by inserting a <=1V audio signal at the top of the audio potentiometer.??
You will need a rf detector probe to measure output of the BFO oscillator.? There are on-line instructions for buildindg your own.??
Using a 100 pf capacitor you can inject RF ahead of the BFO mixer and should hear that on the speaker...assuming that your audio and BFO sections tested good.??
Then move the RF input upstream toward the antenna and verify that each sectiom works.??
Once you understand how each part of the circuit works it is not that complicated to troubleshoot.? Take your time and think through what you are doing...and ask questions here if you need more help.??
On Thu, May 23, 2019, 11:49 PM Michael Herron <k7mh@...> wrote:
I have a Bitx 40 I am troubleshooting that a friend put together. The display comes on okay and covers the entire 40 meter band when I tune it. I do not get any indication of it receiving nor any volume out of it with the volume control and an 8 Ohm speaker soldered to the speaker leads.
I have watched the troubleshooting video. I do not get any noise touching a probe to the center conductor of the SO-239 and no antenna attached. I also do not get any noise when touching the probe to C107.
The video does not talk about what to look for if that occurs.
I was hoping that someone would have some ideas where to start out with this problem. I have checked the volume control a couple times and it is wired correctly. I have not yet checked the current draw of the radio
as I will have to dig up a power cable I have for doing just that.
Any assistance or tips on figuring this out is much appreciated.
Mike K7MH.
