New, strange RFI on 20 meters - RFI Forum at eHam.net

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eHam.net Forum : RFI : New, strange RFI on 20 meters

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New, strange RFI on 20 meters	Reply
by W2MV on September 1, 2009	Mail this to a friend!
I have this intermittent RFI on 20 meters: pulses, easily seen on my IC756PRO3 scope, with a bandwidth of approx 20 KHz. This 20-KHz-wide "window" of interference moves up and down the band...slowly. The NB seems effective attenuating the pulses...about S8. Any ideas?

RE: New, strange RFI on 20 meters	Reply
by WB4BYQ on September 2, 2009	Mail this to a friend!
the noise could be coming from your home, or from the neighbor home thru the ac power wiring. the noise sounds like a switching power supply on some type of electric device. such as a battery charger for aa, aaa,c, d cells, or cordless drill, vcr, dvd player. try moving around your area with a hf radio and do a little fox hunting. look for the power poles and where the lines drop to the house. put in attention on the receiver when you find the noise to zero in on the house. common-mode chokes will fix the problem in about 95 percent of the case. see if this information will help. http://atnm.mcars.us/HomeBrew/WB4BYQ/CommonModeChokes/ http://www.olympixcorp.com/rfchoke/ferrite.htm

RE: New, strange RFI on 20 meters	Reply
by K4TL on September 3, 2009	Mail this to a friend!
I had RFI similar to what you describe. It was my notebook computer...didn't have to be on, just plugged in.

RE: New, strange RFI on 20 meters	Reply
by WB5JEO on September 3, 2009	Mail this to a friend!
Without exploring the possibility in technical terms, I wouldn't be surprised if it was a battery charger that's changing characteristics as the charge progresses.

RE: New, strange RFI on 20 meters	Reply
by LA9XNA on September 14, 2009	Mail this to a friend!
Try to feed your tranciever form a 12V battery with enough capacity to keep it running on RX and check if the RFI is still there. When you are alone at home turn of all your cuircuit breakers, if the RFI is still there it is not in your house. If it is gone start to energice one and one cuircuit in your distribution board until it appear. Turn the CB of and check throug all the other cuircuits just in case. Disconnect all equipment on the cuircuit with RFI and turn it on. Start to plug equipment until the RFI is back and you got your illdoer.

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