The ZS6BKW not bad, I had one up for a while. The Window line should be kept away from other metal objects, and putting a few twists can also help prevent it coupling with things based on what others have said - thou someone may have actual data on that/my terminology may be off - I've not worked with the stuff much. A good 1:1 current choke should be used where the coax meets the balanced line. I recently converted my ZS6BKW into a 40ft elevated (base is 10ft above ground) vertical doublet using a 40ft Spiderbeam fiberglass pole, with the 450 ohm line leading away at 45 degree angle to an AH-4 tuner, one side to ant terminal, other to gnd lug (gnd lug not connected or grounded to anything else), the coax and control cables have chokes which float the tuner above ground. This works fairly well from 40 to 10m. It's not too far behind my 80m OCFD at 55ft in performance. Find the blogger link on my QRZ page (couple posts down from the top now) for more about it. Having said that, if you can get a horizontal antenna around 1/2 wavelength high on its lowest frequency or at least on 20m it'll outperform a vertical in most cases. Exception being 80m for NVIS where having it under 1/2 wave length high is better for example. If you can I'd run the coax along the ground where possible, the dirt acts as a lossy media and helps prevent currents/noise traveling on the outside of the coax. All my coaxes follow the foundation of the house just below the surface to where the shields are grounded and enter the house (get the ARRL grounding and bonding book to know how to do grounding right). WA7ARK's advice is good info too.