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I am experiencing a weird phenomenon with my class 1, 15 Volt, 1000 watt SMPS with an isolated input and output grounds. The AC input (PE) ground connection has continuity to the SMPS chassis. When I touch the power supply chassis, I get a really loud hash of interference.

Based on the info provided below, can someone offer any tips on how to eliminate this "touch" interference problem?

I have mounted the SMPS in a rather large aluminum cabinet. The 120 AC ground is connected to the SMPS AC ground (PE) connection and pigtails over to cabinet ground (short run of 3 inches). On the DC output side, I have a class C linear amplifier. The circuit board ground, heatsink and coax connections of this amplifier are connected to the cabinet. In the process of eliminating some high frequency interference to the amplifier I added a differential mode choke (DMC) between the DC output leads and the amplifier, which works extremely well. I also had to isolate the SMPS chassis from the cabinet with a sheet of plastic. If I let the SMPS chassis touch the cabinet or if I touch it while isolated on the plastic, I get really loud interference.

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  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$ – Voltage Spike May 28 at 13:53
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Although there was plenty of interference typical of a high power SMPS, the end result of my problem was a poorly grounded RF coax connector that directly connects the receiver with the amplifier. I used RG400 double shielded coax which may have helped eliminate interference as well. RG400 is silver plated double shielded coax designed for this purpose.

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