I was getting tones in some stations, and I think it could be local electronics, like when someone turns on their TV.
Checking other Kiwi SDRs later, on average they are getting stronger, clearer signals from a given station in the 6.9 mhz range. I think my large loop antenna, with 120 feet of wire, favors the lower band more and also picks up more noise from the houses, so I'll have to check into a different antenna.