RF Testing the computer

Computers of all kinds generate RF energy. This one is no exception.

I have the computer sitting on top of some radio equipment. Everything has a ground wire tied to a 20 point buss which goes to the service entrance ground where an 8 foot ground stake is driven in Earth. It's about 40 feet from the equipment.

With all the screws tightened on the case, very little noise gets into the receivers (10khz thru 490mhz). In fact with the antennas connected, I really can't hear any interference. I thought there would be more.

However, when the amplifier (Ameritron AL-80B) is running in CW mode on 14 mhz, PI1 (primary computer module) gets confused. Not surprising. The computer is sitting on top of the amplifier running 900W out.

I put a single ferrite bead on the hdmi cable coming into the computer (the RF output cable is inches from the hdmi cable) and problem solved! I'm really surprised about this.

Also what I'm surprised about is the TP-Link router is not affected by high RF, being that it's in a plastic case. I use RG-400 as interconnecting RF cables, all soldered with silver solder. It's the size of RG-58 but double shielded and rated at 30 mhz to 3kw. Really good stuff.

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