Here we go again. Yep you can also wind the popular 49 (or 64) to 1 UNUNs with a single wire. You actually get a better performing transformer than the traditional two wire method.

Didn't bore you with every detail, so if you missed the 9:1 UNUN video it's here:    • Single Wire UNUNs  a quick 9 to 1  

Here's a great primer on the advantages of autotransformers by Larry W0QE:    • #87: Measuring Coefficient of Coupling