Paul Jorgenson KE7HR
I measured one of my 40 meter LPF from QRP-Labs (I am working on another filter project anyway) with the VNA-2180.
In the transmission mode the filter looks like it should. In the reflection mode, with a good 50 ohm load, the filter has a SWR curve that is not flat but rather what Wes was expecting. I guess I better stop replying to postings at 3 am...
Screen shots attached.