"If that really is the case, there would seem to be a fault with your power 
supply. The secondary (low voltage) side of a PSU should never be connected to 
ground. Both poles should always 'float'."

Many of the currently marketed small switching supplies have the same internals 
and only differ in branding, rear connectors, and metering.  I own two 
Jetstream switching supplies and there quite a few "badge engineered" power 
supplies that use the same internals.

These power supplies most certainly do have the negative output terminal 
connected to chassis and mains supply ground.   No, you can't isolate the 
output terminal.

I was remined that the negative terminal is not isolated when I used one of 
these power supplies to drive the reversible DC motor that tunes my magnetic 
loop.  One direction works ok, the other direction lets smoke out of the wires. 
 If you want to feed reversible polarity DC up the coax using a pair of bias T 
then the PSU better be isolated!

Opinions on whether PSU output terminals should float seem to be quite stong so 
I expect a protracted debate.

73,
Andy, k3wyc
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