[HomeBrew] A quick toroid "use" question

[jkearman at att.net [Jim, KR1S]]

Phil,

You should be able to see the effects empirically by building the filter as a breadboard and moving the individual inductors. I have built some tight double-tuned bandpass filters (one is 100-kHz @ 6 dB, fo= 2.2 MHz) and the way I reduced coupling was to mount the coils at 45-degree angles, like so: /-\-/-\ where the hyphens represent capacitive coupling between inductors. I also mount a piece of double-sided board between the inductors with a small hole for the capacitor, but I'm not going to try to represent that in ASCII. :>

Build it, test it, rebuild it. If it works the first time you didn't make the specifications stringent enough. 

73, 

Jim, KR1S