Well, this IS the mobile forum, but I suspect you could use a mobile antenna for another use and/or position?
The issue is the PVC used. While PVC is okay for some antenna parts, wherever there is high voltage—loading coil in this case—the losses get rather excessive, whether or not it is used as part of a mobile antenna. White PVC ages poorly in sunny climes, causing it to crack which adds to the loss factor. This said, if you're trying to get by on a shoestring, there are still better ways to accomplish an adjustable coil, regardless of its final use.