RF Noise from your computer driving you nuts ?
After examining many different ATX Computer power supplies this EMI filter is the main parts difference in RF noisy or quiet supplies. The RF switching noise mainly radiates out the Input 120 VAC Power cord and not the many internal DC output wires inside the case.
Here is a low cost part to add to your computers RF Noisy switching supply. Substitute this $1.50 EMI filter, for your current 120 VAC inlet socket. Part # socket 06GEEG3E INLET. If there isn't enough inside space (as its 5/8 inches deeper than most socket only connectors) , hang it outside 5/8 inches using metal spacers and longer 1 inch bolts. No voltage will be exposed as the enclosure is metal. This schematically is a double section balanced, lo pass pi-net filter. With a .1 UF cap across inlet and double 2200 PF caps bypassing each outlet leg to ground. Each series choke is rated at 8 Amps @ 120 VAC and is .8 mH. After mounting add a additional cap inside shunting the outlet of .33 uF safety rated at 250 VAC. In Common mode its attenuation is 24 Db. @ 1 MHz, 35 Db. @ 5 MHz. and 40 Db. @ 10 - 30 MHz. These attenuation specs are without the .33 Cap ! Many people cannibalize this more expensive 120 VAC filtered connector from higher quality switching supplies they aren't using anymore .......
One Manufacturer is Delta Electronics, Inc. Part # 06GEEG3E Part suppliers Jameco has many types
All Electronics EMI-62 $1.50 ea Although this has right angle terminals it might be mountable Lantech
07/30/2009 Back to Ham Index Page Back to Home page