Re: Radio Noise from PV System
interesting test results ... about 20 Db reduction in noise signal is not bad for your first try.
RE inductors, you probably do not need a lot of L. If you had some powdered Iron cores (often painted red) this would porbably be OK. The most common Ferrites by far are type 43. This is a VHF material, and not very useful in the HF range. Type 31 ferrite material would probably be your best bet, but is is not common at all, and furthermore, there are almost never any marking on ferrite cores or clamp-ons, so it it difficult to determine the material with the eye.
Perhaps, as an experiment, you could try 20 or 30 turns of #10 solid (if possible solid) wire around a 1.5-inch PVC pipe or something, with capacitors at each end, this might be in the range of something useful. Solid wire is just a bit easier to work with, as it tends to stay put. You may find better rusults, later, if the inductors were divided into two sections, with capacitors at the center point of the coils. Use an inductor/capacitor set in the Pos and Neg leads of the CC It is possible that the noise currents in the capacitors might trip GFIs in some systems, but you probably do not have them. As your filter becomes more effective, you would need to pay more attention to coupling between the input and output of the filter, perhaps using a shield near the center.
As you know, each additional Db of attenuation of the noise tends to come at an ever-increasing cost -- diminishing returns.
Off to a meeting. Good Luck, please let us know how you do. Vic
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