Dreams come true. I have been able to assemble four leading analog noise reduction products for comparison, real world and lab testing.
I have been experimenting with and writing about RFI reduction for a few years. My main tool for analog noise reduction has been the wonderful ANC-4 antenna noise canceller, first produced by JPS and later by Timewave. With a few well placed noise antennas, my ANC-4 does well reducing point sources of RFI in the neighborhood.
Several competitive alternatives exist. These include the MFJ-1026 noise cancelling signal enhancer, and the X-Phase QRM Eliminator. And then there is the top-of-the-line DX Engineering NCC Receive Antenna Phasing Controller. Prices range from $20 for the X-Phase kit up to $850 for the NCC device.
We know that all of these boxes work by phase shifting signals from two antennas against each other. Typically, you can find a sweet spot where the amplitude and phase of the offending signal are reversed between antennas and the offending signal cancels out. When used with two antennas, I call this technique spatial interference filtering.
Since they work at the RF level, these devices perform analog noise reduction.
For years, I have longed to compare all of these against each other in a real world experiment. Well, my dream has come true. Thanks to the loan of an NCC and MFJ from some local hams, I now have all four sitting in my radio shack for a short period of time, as shown above.
Analog Noise Reduction Comparison
With a few patch cords in play, I will be able to test each analog noise reduction device in two ways. First, I will phase my main antennas against a selected noise probe, which I have described previously. Right now, I have two noise probes, one at each of the west and east ends of my property, with the main antennas in the center on a fifty foot tower. Second, I will phase my two active loops, spaced 100 feet apart.
At this point, I have no idea which will perform best or worst. I am guessing the X-Phase will be worst, and best will come down to the ANC-4 or NCC. The proof of the pudding will be in the eating, as they say.
As a caveat, all of these are used or home-made circuits. I am assuming they are working as designed, but I don’t really know for sure. But I will compare my results to some video demonstrations done by others online.