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?>>>> I'd worry about that later, and if I needed filters, I'd filter at the noise source. Unless you look at a Star Roamer or some other vacuum tube vintage receiver, you'll find most radios are extremely good for internal shielding of mains or power supply leads to the receiver RF system. In my experience, most leakage problems are in marginal shield grounding connections in phono plugs or poor external equipment design, and not in radios at all. For example, plastic boxes with wires for jack ground leads inside are hundreds or thousands of times worse than anything getting into the radio. When external connections are cleaned up, with any modern solid state radio I have owned or used, the issue becomes devices radiating out to antennas, which then pick up the noise. I had a particularly difficult computer supply. Rather than do extraordinary and difficult things to a dozen points in the RX system, and move my antennas further away from the house, I cleaned up that supply with a filter. A normal station with proper attention to common mode suppression on feedlines at the antenna, and good connections on shields, should not even need a desk ground. (One exception might be power line safety. My old two-wire tube gear, like my Ranger II and HQ-120, has safety grounded cabinets.) 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?>>> The only cases I can think of, where a large desk groundplane might reduce noise, are if: 1.) The antenna has significant common mode current that makes it all the way into the house. For example, look at a longwire shack ground. An end fed longwire antenna is a system with terrible common mode, as are "end-fed dipoles". http://www.w8ji.com/long_wire_antenna.htm 2.) There are poorly constructed 'boxes" in the receive path. The groundplane and shield path integrity in receiving paths is critical. 3.) Internal shack cables have poor shield connections. 4.) Some device in the shack, or near the shack, is exciting terrible common mode RF currents on wiring. Personally, I'd never bother with an extraordinary desk ground. I'd fix the real problem or problems. 73 Tom _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK