The W7NQN line filter is a differential-mode filter. You need a filter that is designed for common-mode filtering.
Dave WX7G On Jun 21, 2012 10:32 AM, "Wayne Willenberg" <[email protected]> wrote: > As I mentioned in a post a few days ago, I am at the very beginning of > being able to operate on 160 and 80M’s. (To date, I have only operated on > 10, 15 and 20M.) I have been doing a lot of reading, primarily ON4UN’s > “Low-Band DXing.” > > > My rig (FT-dx5000) is located on a desk. Immediately under the desk is my > computer, and just above the rig is a shelf on which sits 2 flat-screen > monitors. > > > One of the points made in “Low-Band DXing” is the necessity of reducing > noise in the shack. The author states at page 7-75: “It is essential to > feed the equipment at the shack through high-quality mains filters.” In > looking for such filters, I have come across the W3NQN AC Line Filter. It > seems to be built with quality components, but I have not been able to find > any specs on the amount of attenuation it provides to EMI and RFI noise at > various frequencies (either common or differential mode). Could someone > recommend a “high-quality mains filter” or comment on the W3NQN filter? > > > The author goes on to state: “The bottom side of the operating table in my > shack is completely covered with aluminum sheet. This represents a lot of > capacitance and virtually zero inductance, which is just what you want! > Quality mains filters are bolted directly to those sheets and the mains > outlet to which the equipment is connected is connected as well. The > ground plane is connected with very short low-inductance wide straps to > long copper ground rods.” Would someone please explain to me the purpose > of this ground plane and how it helps reduce noise? How does “a lot of > capacitance and virtually zero inductance” under a transceiver help reduce > noise? > > > Thanks in advance for advice and help for a newcomer. > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
