Measuring the low power is not a simple task using common power-meters so I put on the work my NRP-Z11 Rohde-Schwarz sensor.
The sensor is able to measure very accurate the power between 200pW and 200mW (-67dbm - +23dbm) in the 10 MHz - 8 GHz range.
In the setup I used a BIRD 50A-MFN-20 attenuator (-20 db) and took measurements under that 23 dbm which can hurt the sensor.
I measured the power for "0", "5" and "10" on the "RF Power" Menu.
The results are in the XLS table below:
LE: For 5 and 10, the power is in W not mW. The above table is image and I cannot correct it.
And here is a printscreen of the R&S program:
1. I had a revelation: the sensor is rated for frequencies above 10 MHz so the measurements below that frequency shall be taken with circumspection. Sorry I forget this, I rarely use it to measure the frequencies below 50 MHz.
2. The results are from my ICOM IC7300 and can be or not consistent with other similar radios.
3. LLE: I measured also with a AD8307 sensor and the values are the same!