I should have tried this a long time ago. It works great. The power supply that I picked up at the Kempton Park rally many years ago happens to have a 25 volt unregulated output. Coincidence you say? I think not. TRGHS.
Farhan provides a really excellent description of how to do this:http://hfsignals.blogspot.com/p/25-watt-linear-for-40-and-20.html