For my own reference as much as yours, a little more detail on the balun I'm using with my new Windom antenna. The starting point was this web page.
The PVC pipe on hand here was 1-5/8" in diameter, so I dropped a turn (or a little less -- just over 11 turns for each of the two wires), figuring if it didn't work, I'd start over. It's also only got one color of wire, as I have a nice big spool of sky-blue insulated #14, purchased awhile back for antenna experiments. I scribbled on the ends of one winding with a black marker. You don't even really have to do that, since the bifilar windings are flat: the wire that starts on top, ends on top. Here's the completed balun: And a close-up of the connections at the coax end: The top end is just 6-32 nuts and bolts (mostly brass) and solder lugs.
Here it is all wrapped up in self-amalgamating tape: It didn't change the tuning, so I guess it must be okay stuff at 7 mc/s.
Refinements: use fatter brass hardware for the antenna connections. Use polystyrene drain tubing, sold as "styrene" for the coil form: it has better properties than PVC at HF. Mount the coax connection facing down! And you could do like the pros and encapsulate the whole thing in PVC pipe. (I have one somewhere around here, a slightly more sophisticated trifilar job, coated with epoxy. It had held up well, last time I saw it. --If I could only remember where!)