9:1

I got round to using this.  Well, I didn't actually use it but at least I assembled it into its intended form.

9:1 ratio isolation transformer.

Primary: 2 turns
Secondary: 6 turns
Core: BN73-302 Binocular Ferrite 

Another step towards experimenting with a loop-on-ground antenna.  It's dark now though, and I'm going to play radio rather than building more things now...