I think I have a misunderstanding regarding tuning the USRP.
I have connected the TX-A directly to RX-A. I am plotting the FFT of both the transmitted and received signal. I have tuned RX to 0 Hertz so I expect the positive frequencies to look the same up to noise affects.
What I get instead is mostly noise:
Occasionally I get blips of a signal like this:
The GRC graph is also included: