Hi guys
Let me share what I've done about reducing noise in the Shack, not all station has this kind of configuration, you may not need it. 1- Tom is 100% right about common mode noise. I killed all common mode noise outside the Shack. My desk is in the corner of the house and I'm using two steel galvanized box, one for AC with a huge common mode filters made with wire #10 and FT270-31. The second 24x24x8 for the RX and TX cables, all grounded inside. The RX cables have also FT240-31 chokes with RG142 cables. 2- The 220Vac enters the wall and is connect to another filter with very large surge protectors and feed my amplifier. After the filter connected to a large aluminum bar 8"x 1/4"x 72 " followed by an 1 KW isolation steep down transformer to 110Vac. It is important to avoid ground loop using only one point of grounding. 3- EMI/RFI has two components, electrical and magnetic field must be blocked. My RX antennas has low gain and they work near RX noise floor ,that requires a high gain preamp, my preamp has >40 db gain. Aluminum boxes are not enough to kill the magnetic field noise from the PC and from my 2 LDC screen monitors, the solution was steel tinplated 24"x36"galvanized steel plate bellow the desk and to build a large box 20" x 30" x 3" to install all preamps and the RX switches inside. 4- Also there is a long ground #00 cable around the corner of the house with ground rods each 10 FT, one leg is 40Ft log and the other is 60 FT long and connected to the house power meter ground rod. at the end, like NEC requires. That builds a huge low impedance ground protecting the house and the shack. It is a good ground but for protection it is never good enough. If my station has a big secret it is the ground system for sure, one for RF and another for lightening connected together in one point by a large galvanized 4"steel pipe between the box in the house and the box in ta the base of the TX tower 70 FT apart. All my cable runs inside a galvanized steel pipes to cut the magnetic field. I know it is overkill the problem but I'm glad I did it that way. Regards Jose Carlos N4IS _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
