Here's a screenshot of a 'hacked' Pluto transmitting a two-tone signal as received by an Airspy HF+ which is probably the best SDR you can buy for reception at 145MHz. As you see, the transmission is nice and clean.
Due to the design of the AD9364/AD9363, if both, the TX and RX Local Oscillators (LO) are set to the same frequency or very close to each other the TX LO may leak into the RX path. Monitoring your own signal with Pluto in full duplex mode is not recommended; use a second receiver instead.
If you do monitor with Pluto in full duplex then turn the RX Gain to 0dB to avoid overloading the receiver stages.
Here's the two-tone setting.