Our company sells automotive aftermarket products worldwide. We routinely test our products to the European Union EMC standards. We needed an RF signal generator to replicate one of those tests. The Simple USB Powered Signal Generator was one of our BEST investments. It has been accepted by our electronic engineers as a good way to test EMC susceptibility during product development.
This is a link to the review in EDN of 2 Nov 2013.
http://www.edn.com/electronics-blogs/the-emc-blog/4423710/Review–inexpensive-RF-generator
This calibrated signal source is a beautiful instrument. I have checked the output levels on both a Spectrum Analyzer and an HP-435B Power Meter and the levels were settable to well within 2 dB over the 65 dB dynamic range. I have not tried the FM yet, but the CW is very nice.