![]() ![]() The biconical was "cut" for use above around 136 MHz but I also use it for FM reception a lot of the time (when my oher antenna isnt working well) and there again a balun/unun makes a huge difference. #Sdr diy antenna tv#(usually its vertical and hangs from an almost invisible anchor and hook in he ceiling when its being used in vertical mode) It uses a #61 core and only two turns on each side (thats what is commonly used in 75:300 ohm baluns for broadcast TV use) to cut down the noise on the feedline which is absolutely necessary. that antenna also seems to work fairly well for some VHF-FM reception from NYC FM stations (its quiet, which is what I need for music) I also use a homemade biconical antenna (using two plastic rings from a knitting hoop as the means of separating the wires at each end so its biconical) which is coupled to the coax by means of a small 4:1 balun right at the feedpoint. which works quite well considering my noisy QTH) the fact that I'm using #43 means this approximately 15 meter long piece of copper wire running out to a tree in my backyard - a fairly short, low antenna, for HF, honestly, with the highest point off the ground maybe four meters off the ground, if that. #43 material probably is not the best for the very lowest frequencies but it works (I dont care since I now have a "Pa0rdt mini whip" active e-field probe for them, made by a ham in the Ukraine- he sells them on ebay. Like you I only use it for receiving so its wound on a 50 size core, very small. I'm currently using #43 material in my current one. You should notice an immediate reduction in noise if you can just get the wire out into the clear a bit. The first image is a 9:1 Unun design that I have been using for years. Designs Ive made many times with success. They are all what I would describe as keepers. (especially when its been dry) I am going to add some small images here (starting with one and adding some from my other computer in a bit) to give you something to go on to get started. Because if your situation is like mine the noise is on the AC side. Since your#1 problem is noise, (mine is too - really bad so thats a situation Ive dealt with a lot) you might also want to try galvanic isolation using a simple 1:1 transformer through a toroid attached to your coax from your receiver with the secondary your antenna and the best ground you can find, preferably NOT your AC ground. A binocular core is particularly useful because you can get a lot of mutual inductive coupling with a short wire length which translates into broadband operation and I suspect also higher efficiency. In a pich try cheap RFI beads, they often are made of #43 material and work well.just "adjust to taste", less turns for the higher frequencies or more toroid enclosure of the wire as you would get with a real or simulated binocular core. I personally often use iron powder magnetics because they work better at higher frequencies and require fewer turns. For your unun.or balun, Popular choices for HF are #2, #6 ferrite and #43 iron powder materials. OTOH, putting ferrites around the power cords for these lamps might help a lot by limiting the LED lamp noise between it and its "antenna", its power cord. although putting a common mode choke around a single antenna wire seems as if it would not help, in some settings indeed it does help when the interference is higher in frequency than the desired signal So its unlikely to help in your situation. ![]() Some materials do much better than others for noise reduction, but those kinds of magnetics also likely are more expensive. If you are able to, I would buy a large quantity of them so you can use them liberally wherever they do the most good. Split beads of ferrite material are great to have in quantity for reducing noise. I'm guessing the lights are not in your control? (you could probably filter out the noise if they are) The schematics below are all useful with toroids you might have laying around, and consider that if you use coax and site the balun or unun at the antenna, and perhaps just the coax runs near the LED lights, but the antenna is elsewhere, right then you will likely reduce the noise. And some YT videos from K7AGE: ]DIY 2 meter antenna ]DIY 10 meter antenna Like these: (A lot of it come from ) And some other articles that might be useful. There's a lot of articles on the net if you're into building antennas.especially if your into SDR / Ham radio and receiving signals. ![]()
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