I have almost 20 years of experience testing digital logic / memory ICs. Due to my expertise in test system software design, I have been chosen to start developing a test system for RF transistors. I am used to looking at signals in the time domain (delay, rise times, voltage / timing margin, etc) and the frequency domain is very new to me. Is there a recommended text book or website to get me up to speed on the basics?

The Rf Test Field can be challanging for a newcomer. My suggestion would be the Instrument manufacturers themselves. Agilent, Rohde & Schwarz, National Instruments and others have many white papers, technical notes and other reference sources. Agilent has always been great at producing numerous application notes and the operating manuals can all be downloaded at no cost and are valuable resources on how to make the measurements, how to use the instruments and tips for using the instruments. Rohde & Schwarz has several small books at low cost on Vector and Spectrum Analysis. National Instrument also has many on line resources. Most of these resources are free for download. I have collected most of the best over the years and have built quite a library to use when needed. Agilent and NI have many code examples that give an easy start to automating. Another method would be to hire a consulting resource like myself to jump start you into the field quickly and do some initial coding to get you started.