submitted by Tom K1JJ
You can get an idea of how your audio low end is working by turning on your crystal calibrator or just tuning in a solid carrier. Tune it thru the zero beat and you will be hearing VERY low audio frequencies that should rock your speakers. In fact this can be used as your audio oscillator. Just hook the scope to this same detector output and hook in a freq counter (if you have one) to see and measure the actual frequencies.
Either way, study the scope carefully and watch how high and low you can see and hear audio as you tune thru the carrier. Especially watch to see that the scope (detected audio) sine wave stays clean as described in my transmitter sweeping procedure posted a few days ago...
Now the limiting factor will be the filters or I.F. in your receiver