Hi, I wasn't sure where to post this but it is homebrew and it's not working quite right, in my opinion. I just finished construction of a broadcast band stop filter so I can stop broadcast interference to my SDR when I'm listening to longwave. It is based on this design, but I tweaked it slightly using the RF Tools website to cover from 500 Khz to 1775 Khz. After some tweaking of the toroids as I realized that almost all of them had one or more too many turns, I managed to get the filter as close as I could. However, I am getting excessive insertion loss. At first I attributed it to perhaps the fact that I am using a random wire antenna with a 9:1 unun, but even using a 50 ohm dummy with an RF noise source, I am still seeing a roughly 20 dB insertion loss with the filter. Here are some images: filter schematic -> https://i.imgur.com/NzH1CfW.jpg constructed filter -> https://i.imgur.com/558C8vw.jpg https://imgur.com/a/DDDtdDV Top image shows spectra of the filter; bottom is noise source only. Both have 50 ohm termination. Even compensating for the noise source variance, you can still see at least a 15-20 dB loss within the first 250 Khz when comparing the images and according to TinySA. And I confirm this when listening to a weaker NDB on 240 Khz, barely copyable with the filter, fairly strong without. I am at a loss as to what's causing my RF loss and welcome your help. This is the first time I've ever dabbled in such an adventure and just hope it won't be the last.