Re: Variable power control
Karl Heinz Kremer, K5KHK
There is an HP application note about PIN diode attenuators: http://www.hp.woodshot.com/hprfhelp/4_downld/lit/diodelit/an1048.pdf
I was just about to recommend a PIN diode attenuator as well. The device used in this particular configuration reached it's end of life, and may be hard to get soon. There are alternatives:
The data sheet has a chart that shows insertion loss based on frequency and control voltage.
Karl Heinz - K5KHK