HFU HF Underground
Technical Topics => Equipment => Topic started by: JustGreg on March 16, 2026, 1403 UTC
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I have been looking at small loop antennas for the time that I can not have a long wire antenna. I currently have a 40 meter end fed half wave (EFHW) that works great, but, time brings changes.
I think I may found a good loop antenna. It is the K-480WLA loop. I found it on Amazon. The cost with tax and shipping was about 150 dollars. It is available with as a unbranded product or with multiple brand names.
It is advertised as having frequency coverage up to 500 MHz. It has an internal batter and can be charge by USB charger. The interesting features are it has a RF gain control and multiple band filters. Its output can be configured for no filter, medium wave (MW), shortwave (SW), FM broadcast (FM), Airband, UpperVHF (UV), and 6 meter (6 M).
It comes with the power supply/filter unit, loop amplifier, spring steel loop element (about 27 inch diameter), interconnecting cable (about 30 feet), mounting hardware, some PVC pipe pieces for mounting), SMA to various connector adapters for use with different receivers antenna inputs, and a reasonable English language manual. The items have a good quality feel loop amplifier seems to be watertight for external use. The loop amplifier has screw terminals for the loop element and a TNC connector. I brought a TNC male to SMA female adapter to allow me to use my existing cables.
I mounted it to a wooden test stand and have been using in my house. It does have a good response up to about 180 MHz. About 180 MHz, I have my doubts. I did find the RF gain control and various filters were a help in listening to stations.
AM medium wave reception With the 40 meter EFHW is marginal due to local interference sources. The K-480WLA allows me to listen to AM medium wave station. The loop antenna is directional and this helps in reduce interference effects. I found the MW filter was needed and RF gain was set to the 2/3 maximum position for best results.
HF performance was good for general listening, but, the K-480WLA is no DX antenna. It is fine for the US and Canadian HF broadcast stations. If HF propagation is good then one can hear weaker non-broadcast stations. I have listened to some of the stronger 43 meter stations. It has acceptable performance with SW filter and RF gain set to the middle of
the control range.
The FM broadcast performance is very good. The K-480WLA is directional in FM band. However, the FM maximum point is at right angle to that of MF/HF maximum. I got the best results with FM filter and RF gain set to a little below the mid point of the control range.
The Airband did work, but, I have a lack of signals in the area. I did manage to hear a couple of planes.
This is a keeper for me. I have used the YouLoop, MLA-30+, and LZ1QA loop antennas. It definitely is better the YouLoop and MLA-30+ loops. The performance of both the LZ1QA and K-480LWA are similar. However, the filters, RF gain control and watertight construction give the K-480LWA the advantage for listening.
Currently, I have TEF-6686 receiver connected to it for MF AM and FM broadcasts. This is a good combination for me. When the weather improves, my plan is to mount the K-480LWA above my metal roof. This should improves the HF performance.
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$69.89 from Ali Express
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I have one. I measured the wire circle & cut a piece of 1/4" copper tubing to match. Then, I hammered both ends flat & drilled them. I mounted it just like the wire should be. I don't know that it performs any better, but it's a heck of a lot more sturdy.
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Tried a K480WLA once it was a dud out of the box and decided to stick with the K180. I think these are phenomenal antennas either way - I like the DmgicPro seller on amazon for it - have purchased 6 of them to pass out to other hams. I pair it with a sdrplay rsp dx 2 using sdrconnect software. Dont know of any better setup for the price, for what it is worth also the rsp1b entry level model from sdrplay is also plenty - im a nerd that wanted 3 antenna ports ;D