Sorry I identified "Corcom" incorrectly. I checked a sample and the actual filters that I used were Delta Electronics 05DRCG5.
http://disti-assets.s3.amazonaws.com/quistelectronics/files/datasheets/4322. pdf Tom -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Tuesday, July 23, 2013 3:42 PM To: topband@contesting.com Subject: Re: Topband: Desktop Power Supply Brand/Noise Question > I simply purchased 10 Corcom filters on ebay ( I think they were $2 > each + shipping). I cut a power supply cord (universal plug type) > about 6 inches from the computer and wired the filter into a plastic > electrical box with the other end of the cord out the other end of the > box. I used standard electrical cable clamps to secure the cable to > the box and added the cheapest electrical plastic cover. The whole > thing cost me about $6 each and I built 5 of them in a couple of > hours. The boxes live behind the computer so the blue color > appearance doesn't matter. When I purchased newer computers, I just > moved the filtered cord to the new computers. That's OK, but be aware the corcom appears to be a typical design with limited value for choking isolation. See this page: http://www.cor.com/pdf/DA.pdf The windings appear to be linked magnetically, and the ground appears to have no isolation. This seriously limits the effectiveness of the filter, making it similar to beads over cords. The worse part is not having isolation on the ground path. The best part is the filter adds bypass capacitors, which when properly sized either assist any added iron core cord chokes, establish a low or controlled differential and common mode impedance, and often do a better job than any practical choke system or core does. I use a filter like this: http://www.w8ji.com/images/filters/filter7.gif It isolates and bypasses all three wires. One of my tricks in a suburban environment was a three wire plug with two .01 uF 250VAC UL/CSA bypass caps. No cord or anything on it. I moved that plug around my house until I found a sweet spot that eliminated conducted noise from the house next door. They had some battery charger that just tore up 80 and 160 through our common sharing of a pole transformer. 73 Tom _________________ Topband Reflector ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3349 / Virus Database: 3204/6513 - Release Date: 07/23/13 _________________ Topband Reflector