If the power supply is in the SPG zone, you don't want the household AC safety ground connected to the SPG through a second path - the chassis of the supply. So separating the grounds is the correct practice in this case.A second justification for isolating the grounds is to reduce noise on the DC ground.- Glenn W9IQ
i added a dc ground to my astron.a primary to secondary short/leak would put line volts on your radio.not good !!!
The power supply negative is grounded thru the transceiver.