I made up my own spool tensioner...
It's just a length on threaded rod, I machined up some tapered plastic stocks(to center the spool) and an old set of drag washers. I then put one end of the threaded rod in a vice, slide on the drag washers, slide on one stock, then the spool with braid, then the other end stock and adjust the tension with a nut on the threaded rod, then lock the tension in with a second locking nut... OK, that even sounds a bit confusing to me
... but it works a treat!