> This monitor is absolutely without broadband noise emission at any > frequency...
Be careful when assessing noise from shack and household appliances. I have had devices that raised the noise floor by several dB across the spectrum of the band. The noise was so evenly broad that movement in frequency resulted in no change of the noise floor. My own noise mitigation plan includes establishing a reference baseline on all bands using an SDR-IQ as a panadapter with the K3. I first cut power to the entire house, including removal of power to battery-backed devices like the home security system. With the SDR-IQ, screen captures can be saved and archived for later reference. After the initial baseline is recorded, I then apply power to all home devices, again taking screen captures of the bands. Then, one-by-one, I kill power to the breaker panel circuits, identifying noisy circuits. Next, devices on the circuit are found. Finally, noisy devices are worked through the addition of ferrite and CORCOM type CM chokes, replacement of switch-mode supplies with linear supplies, and in some tough cases, complete appliance replacement has been necessary. In the past year, I've either modified or replaced over a dozen devices, most of which are small switch-mode wall warts that power my Netgear LAN equipment. A few days ago I autopsied one of the Netgear wall-wart supplies. There's absolutely no EMI/RFI abatement anywhere in the circuit. The noise floor will be affected by shielding integrity of the rig and shack cabling as well as the type of transmission line used. Folks bringing in balanced feeders to a tuner in the shack are probably most susceptible to home-generated noise sources. I am using homebrewed 600-ohm line to a motorized balanced ATU outside the house. CM chokes are used on the coaxial line portion, but a good bit of interference is being coupled onto the 600-ohm line. As line spacing increases, losses are minimized but noise ingress is inversely proportional to the benefit attained with lower line loss. With the proliferation of SDR receivers, the LP-PAN unit and now the P3, it's easier than ever to identify and resolve noise problems within your own home. Outside the boundaries of your property, more complex DF measurement methods must be used, but its all manageable with good technique and patience. Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
