In his particular case replacing the antenna with a paperclip, bent or unbent, would probably work. A large attenuator in the antenna lead would also do the trick. He's not exactly trying to receive a weak signal. It's simply weak compared to what is around it.
He needs the band stop filter if he wants to wander out to OTHER weak signals. But 100 W next to 120 kW at 3 km distance is one bodacious humongous whomping big signal.
{o.o}
On 20200203 00:48:02, Allan Isaacs wrote:

Back in the 1920s and 30s a common problem was reception of weak signals in the presence of strong local broadcasts (not that I remember.. I just read about it).

The answer was to design a proper RF front end with bandpass tuning etc.

There’s nothing wrong with constructing a tuneable front end for an SDR. In fact the graphical presentation of the spectrum makes it easy to align such a tuner.

Combine this with a directional loop antenna and you have a perfect general solution.

Allan G3PIY