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My first magnetic loop for 2m :)
Really simple construction: bent ca. 2mm brass pipe soldered directly to the outside of an SMA plug, inside of the plug soldered to the red wire as “input coil”. Tunable by squeezing the ends more or less close together.
SWR of <1.2 at resonance, not bad. Impedance is at roughly 44+j2 Ohm, also not bad for totally eyeballing it without any prior calculations.
I can reach the nearest 2m relais just fine at 2W, although to be fair I can do the same with a short whip antenna. More testing to follow. Holy shit, this actually works!
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Magnetic loops are really beautiful for tuning out noise sources and for doing DX in horizontal polarization. Try some two-meter sideband in horizontal polarization.
Thought it’s just FM on the 2m
Nope, I believe 144.000 is 2m sideband.
Edit: Don’t take my word for that though. It’s been quite a while since I’ve been on two meters frequently. But I do know there is a portion on two meters for sideband.
Edit 2: Actually, I want to say it’s 144.200.
144.100 - 144.275 MHz. Calling frequency is 144.200.
2M sideband and VHF DX is a lot of fun. I remember working satellites using 2M/70CM sideband as well.
Sadly I just have an FM radio, but maybe I’ll try it at the local club station. I am not sure how much power it will survive, though.
Good point. Remember that FM is 100% duty cycle where sideband is not. But you definitely do need to keep the power down in order to not fry something on the antenna itself. If you’re not careful, you can get arcing between the plates.
Especially since the “plates” are just some overlapping pieces of the brass coil covered in heatshrink… It makes me wonder how to make a 70cm loop, at that point, the capacity would be so small, I might get away with a horseshoe design of some kind.
Oh yeah, I would definitely be careful about how much power I put into that then LOL.
For higher power, you could use some PTFE tubing as an insulator instead of heatshrink.
T2FD will always have a place in my
heartyard.So, first actual test: The general sentiment is “a few S levels” higher than the original whip of my Anytone 878, with a notable directionality. I can talk to my friend from the other side of the city with just 2W as well. Great success! Also, it survived 7W for quite a while without getting hot. Although my fingers (I was holding it in the air) started tingling a bit ;)