There is a free program for Windows (link attached), that is an audio spectrum analyzer using a mic input.? Process is to tune to an open channel and? view the spectrum.? The spectrum should go from around 500 to 2500, or there approximately.? ?Then use the CEC Memory Manager to adjust the BFO until the noise is centered and about 2.5khz in width.? Seemed to really help with the audio quality of my receiver.
Link to program:
Web Page:
I got this technique from a post in BITX20, though no longer have the link.
What you are doing is aligning the BFO with the crystal filter so that the signal is not attenuated by the filter skirts.
Once the BFO is aligned, then can go back to the main VFO calibration, though I believe that if you truly zero beat the signal, adjusting the BFO should impact the calibartation.
I used this method after setting up the recommended way, and noticed a significant improvement in audio quality and reduction in noise.
