From a review on this site: http://www.eham.net/reviews/detail/9398

"I have been using this supply with my IC-7000 as a base for 4 months now. It has powered the station **Perfectly** but I had noticed on the 75-80 meter band there has been a rather consistent noise floor issue of about S5 which the problem goes away when I switch to a 12 volt battery.
The other day I was rewiring my AH-4 remote antenna tuner when I saw a spark as I soldered a ground lug to the ground wire that was attached to the grounding terminal of the tuner. Nothing was turned on but the power supply so where was this phantom power coming from that my grounded soldering iron shorted out? I took everything offline and measured resistances and found that the chassis of this power supply is indeed tied to the +12V line along with the screw lug labelled with the AC ground symbol. (ground loop incurred through the AC ground lead of the power supply)
To resolve this issue, I mounted the power supply in an all enveloping plastic electrically insulating enclosure, removed the ac ground wire from the ground terminal and tied it to the DC ground on the power supply. Then I took a 250uf low ESR electrolytic, put the + side to the ac ground screw and tied the - to one of the dc ground screws as to make sure that any RF present on the chassis will have a definite low impedance to ground. Result? Dead quiet on 75-80 meters and **at least** 3 S units lower noise on all other bands!!!
I'm really surprised no one else has noticed this issue. Maybe my power supply was incorrectly fabricated? Anyway, I didn't have to void any warranties to fix the issue and now I get SUPER performance on the lower bands!
Another observation- Power factor on this power supply rolls in right around .65-.7 which equates it could be much better. I'm going to throw a brute force inductor in series with the ac supply to see if this addition could bring the power factor up closer to a .9
73
AD0AR Peter Dyrke (upgraded to my Extra) "