Good morning Alan,
I did as you suggested,
I know where the issue is now.
I neglected to take into account the dynamic range of the instrument.
The filter is a 40 meter filter down -78 dB so I was in the noise floor.
I did a cal and tested the nano with precision attenuators from mini circuits.
-10, -20, -40, and putting them together -70.
Down to - 70 dB it reads within .25 dB.
It still would be good to know if the amplitude could be adjusted in the software.
Classic case of pilot error!
Thanks for your help
Ed
