I recently received Radcom the journal of the Radio Society of Great Britain for November.
There is a discussion within which describes the LMX2541, there are different versions dependant on frequency but the
specifications can be found herehttp://avnetexpress.avnet.com/store/em/EMController/RF-and-Microwave/RF-ICs/PLL/_/N-100245?action=products&cat=1&catalogId=500201&cutTape=&filterButton=true&hbxSType=New
Mention is made also of a previous article in April 2012 which discussed the LMX2470. this requires a crystal oscillator at a stable frequency or a GPS source is also suggested. Tuning can be controlled by a PIC but I would say an Arduino would be more suitable.
These circuits are described as fractional N synthesisers which give virtually continuous tuning over a certain range.
Look them up and see if they can help you.
The article is written by Andy Talbot G4JNT with an interesting website at http://www.g4jnt.com/