If anyone is interested, I have put an attenuator on the transmitter output and am putting out -10dBm onto a 20m dipole. I have indicated 0dBm transmit level since there is no way to put in anything smaller.

The location is Friday Harbor, Washington State, and the transmitter is a Raspberry PI with an external filter. So far it has been received by my California station (WB6CXC/6) and WB7ABP. This is a range of about 1100km, or 11 million km / Watt!