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In article .com,
"MojaveDxer" wrote: Telamon wrote: In article .com, "MojaveDxer" wrote: I am getting a horrible buz across the bands that is coming from my neighbors apartment. Would one of those ANC-4 or the MFJ unit get rid of it. Periodic noise, that's noise spaced every few kilohertz is probably a TV, maybe a plasma TV. It's a constant buzz from the bottom of the BCB to 40 meters. I get the same buzz when the dimmer on my halogen lamp is being used. Its so strong that my loop antenna wont null it out. Buzzing noises that are louder at lower frequencies are indicative of switching pulse noise. These square pulses are rich in higher harmonic frequencies. The power of these harmonics drops off the higher in frequency you go. Switching power supplies, gas vapor lights starting up, light dimmers, and other items generate low frequency pulse currents. Another thing happens in the receiver itself. When you hit the front end of a radio with these large low frequency pulses it generates very broad spectrum intermodulation products that desensitize the front end of the radio by raising the noise floor across the bands and also affecting the AGC so even when you are not tuned to a harmonic of the pulse noise it adversely affects your reception. One way you can improve reception in a noisy location is to use a high pass filter with a corner frequency of a few hundred kilohertz. You can see that low frequency pulse switching noise has several adverse affects on radio reception. I have no experience using the ANC-4 of MFJ noise canceling units. -- Telamon Ventura, California |
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