Common Mode Noise Propagation

This is an interesting read

I have noticed that common mode noise on 160M is different at night than it is during the day. I also know that the direction changes, which makes sense – fewer people are watching plasma TV’s or have LED lights on at 2 AM than at 8 PM. Once they turn these things off – then other, maybe weaker – or stronger noise is received, and from other directions. Mike, KJ4Z was over this past weekend, and when I mentioned this he said “it probably propagates”. I said “Bingo” – because this is something I have noticed for a few years.

Rotatable Wellbrook ALA1530LNP loops are fantastic Common Mode Noise eliminators

I’ve been somewhat successful building and installing common mode chokes on my receiving antennas, but the best defense I have against this noise is that I can rotate the Wellbrook ALA1530LNP loops. Besides already being low noise, they operate on the magnetic element of the signal. Now – add the ability to rotate the two that I have phased through the DX Engineering NCC-2, I can mechanically and electrically steer the antennas so they null the noise and then I hear the signal. I have found that slight changes from night to morning occur.

My portable “noise sniffer” – the Sony IC-7600GR

Which reminds me – I need to add some of the common mode chokes that I built for previous RX antenna experiments, and that are just sitting under the house right now!



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