Hello Alan,

Some time ago I have measured the sensitivity of my QCX+ for 40 m with old school test gear:

Signal generator Marconi TF-2019
20 dB Mini-Circuits attenuator
HP-3400A RMS voltmeter

First I have established the 3 dB bandwidth of the audio filter as 170 Hz.

F = 7020 kHz

MDS = 3 dB S/N = -133 dBm

10 dB S/N = -125 dBm

No lack of sensitivity if you ask me!

I can still hear a - 138 dBm signal.
This is due to the human brain simulated 50 Hz filter.

73,
Roelof, pa0rdt