Double-tuned bandpass filter

I made a bandpass filter the other day, but was having difficulty getting it exactly like I wanted messing with the turns on the coil.  Thought it would be nice to have one that I could tune.  Of course, N6QW had something for this.  But the transformer he suggested wasn't available through Mouser any more.  He had a vendor out of the UK, but the shipping was pretty high for just the parts I wanted.

Then later I was looking on Aliexpress, and came across the very thing.  A seller by the name of
"Bohinda inductance coil Store" manufactures the exact thing (their part name is "(7E )42IF123A").  They will also manufacture to your spec and also have "blank" ones for you to wind your own.

I quickly threw together one for 30M (since I didn't want to bother taking the capacitor out for 20M).  Also tried my hand at winding one.  (I got a different design for the build-your-own on accident, but turned out well.)

SSB Success!

Woke up way too early this morning, and ended up watching a bunch of YouTube videos.  One of them I came across was this, which made me realize I had been using the wrong BFO frequency for my radio!  Adjusted things, and I can hear people!  I was doing the BFO on the wrong side of the filter, getting frequency inversion.  For the amount of times I heard n2cqr talk about it, you think I would have gotten it right!

The voices were super quiet - don't have the right gain in the right places - but I could hear it!  I've also got a bit of a ground loop I think, so I had to make sure I was touching the audio amp potentiometer or my amplifiers became oscillators.  But at least now I know I'm not crazy - I really couldn't figure out why I wasn't hearing what I expected.

For my reference, here are the frequencies.  I am doing the 20M band, and the BFO (ch2 here) is at the top end of my crystal filter.  (I measured it the other day as going from ~8.9967 to ~8.9986.)