But you will notice that something happens over at 321Khz and 400Khz. These two stronger NDBs become distorted. If you zoom in on them, it looks like they have picked up a series of hum lines of their own.
This is pretty much inevitable with any form of Noise Blanking.
A noise blanker operates by chopping chunks out of the signal before it gets to the Channel Filter.
Which is another way of saying that it is modulating the signal, hence your Hum lines.
