[amsat-bb] FT-847 - relating dbm to S units

Thank you for reading this.

I'm still trying to determine if the aerial I have is working correctly or not.

If -120 dbm for a 12 db SINAD is considered the minimum usable signal, what is the likely signal level required to indicate an S1 reading (at 435 MHz) on an FT-847 with the internal pre-amplifier turned on?

The Yaesu manual quotes 0.2 micro volts for a 12 db SINAD. How many S points is likely to be?