Trying a Large Magnetic Loop

The NEW KY6R Loop – Now a 25′ Circumference Magnetic Loop – on two 8′ pieces of Redwood

Last night, once I figured out (actually remembered) how the NCC-2 worked – with the two antennas in its 2 inputs, I was disappointed in my “KY6R Optimized 40M Delta Flag”. Sure, it worked, and in a previous test it did work well when phased against the UrbanBeam, but when I compared it to the W6LVP loops – it was noisy and not even as strong as the W6LVP. The W6LVP Loop gave me a more meaningful test baseline. I realized the KY6R Loop was basically a good noise sensing antenna, but NOT something I want. I want something better than the Wellbrook AL1530LNP or the W6LVP Loop.

I ran this by Andy Ikin at Wellbrook, and he said:

“The issue may be down to that the Flag antenna having a 3dB noise figure due to the termination resistance verses the LNP loop having an amplifier noise figure of approx. 0.2dB. Also the LNP by virtue of it small size is picking-up less local noise.

Is your Flag a DHDL or a single Flag? Single Flags and K9AY antenna don’t seem to work in the real world above 2MHz due to signals arriving from too many directions with scattering in the ionosphere.”

BINGO! Andy hit it right on the head, and I then Googled “large magnetic loop” and found a few interesting things. I then opened up an online circle calculator, and looked at what the circumference would be with a frame of 8′ horizontal and vertical pieces. It turns out that its 25′ and that I just happened to have a 25′ piece of LMR-400.

The KY6R Loop is 2 to 3 S units better than the W6LVP Loop, and with its Wellbrook feedpoint preamp and matching system is less noisy, but I will say that the W6LVP Loop is better than the MFJ Loops, but not as good as the Wellbrook ALA1530LNP. I still prefer Wellbrook – but the W6LVP Loop is a fine product, and support from both companies is fast, courteous and educational. I always prefer vendors who take time to make sure you succeed. DX Engineering and Elecraft are also in this “club”.

I just checked 80 and 40M and have found that the KY6R (NEW Magnetic Loop) is a bit noisier – so with the larger size, I pick up more noise as well as more gain – so I will think about what I will do next. Both the small and the large loops are still less noise (and less gain) than the UrbanBeam – on 40M. I might just go with the smaller loop and use the Wellbrook FLG100LN preamps. One idea would be to get some 3/4″ copper ice machine line. As it turns out – I have found that a signal that is Q5 but barely moves the needle is better than S9 swamped with S7 noise – where QSB makes the station fade down in the noise. S Meter readings are not everything!

I think I need to do some A – B tests with weak signals with these two antennas – lets see what I end up with by the time my second FLG100LN gets here – which I hope is before this weekend.

PS – right after I posted this blog entry – the Trane heater kicked in – which totally wipes out the UrbanBeam, but these mag loops let me hear the band. This is very big . . . . AND, I wanted to see if I can hear a low power radio station (5000 watts at night) in Bend, our favorite place – and sure enough, with the BIG mag loop, I can hear KBND on 1110 AM, but with the W6LVP I can hear it, but not nearly as loud. I can’t hear it on either of my regular TX antennas (UrbanBeam and Inverted Vee)

 

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