I've been working on a very simple and inexpensive HF Scalar Sweep set for
testing filters and other frequency dependent devices. It's based on a DDS
frequency source and an Analog Devices log detector. Sprinkle in some PIC
firmware and some Visual Basic software, and you have a very nice little RF
test instrument that rivals equipment costing much, much more. If you want
to see where I am, you can get more info at my web site:

http://mysite.verizon.net/jdrocci/index.html

I have a lot of ideas for expanding the capability of this device. With some
outboard modules and appropriate software, it could be an HF spectrum
analyzer, a return-loss analyzer, an accurate RF probe, and a lot more. I'm
looking for constructive suggestions.

Joe
W3JDR