MLA-S (MMT) QRP Review

I tested the MLA-S (MMT) QRP antenna from my weekend QTH in Divice with power of 4W, using FT8. I had the antenna set up next to the kitchen window. Although I worked with little power, I managed to make some fairly decent connections in a short while, mostly on the first call. Connection distances (QRB) were about 300 to 1000 km. I made a connection with station 1200 km from my Prague apartment with 10W and an antenna set up on balcony on the second floor. I am pleasantly surprised by this, because according to some information from the internet, it is not possible to transmit with MLAs from apartment buildings, where steel reinforced concrete is used. I am glad that my MLA also works in Prague, where our house policy doesn't allow me to set up an antenna on the roof. Thanks to MLA-S (MMT), I can now be on air during the week.

MLA-S Review

I’m very happy to finally own an OK2ER MLA, and what’s more one of the new 2020 “SMART” series - SN 003, equipped with a FCL.

This antenna makes an extremely solid and well-built and professional impression. The 3D printed parts add much to this. The weight of around 1 kg is low compared to copper + large metal capacitor designs, but probably a bit heavier compared to coax-only “travelloops”.

Connected to my transceiver just on receive tuning the antenna felt very nice. No problems with finding bands or band changing. Sensitivity seemed excellent. Tuning is very smooth. The geared capacitor makes settings easy. Surprisingly, adjustments on the higher bands - where you would normally expect broader antenna bandwidths – are quite critical – one mm knob movement can make a difference. There is no hand effect whatsoever. This is UFB - many other manually tuned loops seem to suffer from this very annoying effect.

Band switching is fast and convenient with band settings of 80/60; 40/30, and 30-10m associated with the two plugins and open connection. A minor inconvenience is the location of the jumpers / C at the back of the unit. However, you quickly get used to it. The jumper holder on the central loop cable clip is a great idea.

The attached SWR charts were produced with my NanoVNA/VNASaver. It was amazing to find that SWR’s very close to 1:1 are easy to achieve with the coupling loop more or less in the same position. Tuning the antenna to resonance by ear lands you directly on or very near to the lowest SWR spot. Another half a second tx “tune” and perhaps tiny adjustment and you are set with essentially a 1:1 SWR. Bandwidth is very low on 80m (<10 kHz) - higher on the other bands of course;  proof of the antenna’s high Q.

To me this is an outstandingly well designed, small and lightweight loop antenna considering it tunes from 80 to 10m. This evening, in absolutely miserable band conditions I was able to have a CW QSO with a Swiss station calling CQ with a 569 signal on 30m. The contact was difficult for both sides with several overs due to QSB. But he was running 100 W and copied my 5 W into the loop for a complete QSO! Amazing again. This is big fun of course.

While this antenna may perhaps not win any design prizes, it certainly works very well and is very stable.