> My guess is that the basic_rx host-side driver turns it off, because the > basic_rx doesn't actually use it, so it would be floating, and > thus potentially radiating and causing an issue at both the > fundamental and odd harmonics. Very good advice: https://github.com/EttusResearch/uhd/blob/master/host/lib/usrp/dboard/db_basic_and_lf.cpp#L269 states // disable TX dboard clock by default this->get_iface()->set_clock_enabled(dboard_iface::UNIT_TX, false); Will have to recompile libuhd then, better than generating a new gateware though. Thank you.