On Mon, Dec 23, 2019 at 4:01 PM Martin Potter <ve3oat@...> wrote:
Jerry wrote :
"You need a low pass filter, not a high pass filter."
No, high pass is correct.? Pass high frequencies, but block low frequencies.? Pass the HF stuff and block the lower frequency BC stuff.
The filters pointed to in the links are mis-labelled.? They are high-pass.? Capacitors across the top pass the high frequencies and block the lower frequencies.? Inductors going to ground drain off the low frequencies, letting the higher frequencies pass by.? High-pass, not low-pass.
If the interference is truly from the FM BC stations, and not their AM-band counterparts, then a low-pass filter would be appropriate.
