The Best Active Loop Antenna 2019 = MLA-30?

[alpard]

Good point. 

Here is MLA-30 comparison with other Loops by the youtuber.
https://www.youtube.com/watch?v=V7bp5OII0rs

[alpard]

My MLA-30 plus arrived yesterday.  I temporarily set it up in the room for testing, and it works very well.
I found that,

1. it is very directional. For receiving Radio Japan on 15Mhz, it completely nulled the signal out when positioned East West.
When turned to North South, the signal peaked and copied.

2. Supplied wire element is good for up to about 7 Mhz and above. Below that it degrades performance.  Then when attached with long wire with alligator clip on the element for 6Mhz and below, the reception works better.

I think it is better than anything I have had - long wire and active whip.  I think this is a great DX antenna, but will need to set up on a little tripod, and should be rotated.

It could be set up as horizontal for omni directional antenna, but most BC stations on HF seem transmitting on vertically polarised antenna. But one could do some testing on that to figure out which polarisation works better.

[redhat]

...It could be set up as horizontal for omni directional antenna, but most BC stations on HF seem transmitting on vertically polarised antenna. But one could do some testing on that to figure out which polarisation works better.

FWIW every curtain antenna I've every seen at a shortwave broadcast station was horizontally polarized.

+-RH

[alpard]

Then horizontally installing the rx antennas are OK? You don't need to get the rotator.
Rotator sounds a bit too much hassle due to the amount of cables wired into the control box, and also they tend to be expensive.

[RobRich]

As Chris noted, it is an inexpensive video amp IC with a bias tee power feed.

There is no particular reason it even has to be used for a loop as shipped. It could be used as a remote preamp for a variety of antennas, though I would suggest sticking with something balanced like a dipole, T2FD, loop-on-ground, or similar. It might suffice for a reduced-length beverage as well, though I suspect it might actually lower the actual resulting SNR of a quiet antenna given the amp design. YMMV.

I have a MLA-30 of whatever revision, though I have not done much with listening with it. It worked "okay" in a quick test with an indoor scrap wire loop near an exterior sliding-glass door.

Of note I removed the USB port and bypassed the regulator to feed DC without the voltage conversion. I have not done any testing at difference voltages, but a 9v battery seems to work okay. Lower voltage into the amp might even improve the noise, phase distortion, etc. Again, YMMV.

@alpard, if opting for a horizontal solution, either get it high as possible with a small loop like the one packaged with it to help limit ground losses, or alternatively consider trying it with a loop-on-ground of moderate size.

[alpard]

Thanks for your info and advice.

My 2nd MLA-30 arrived this morning.  It was in a small bubble plastic packet, and very light. I couldn't believe it was the MLA-30.
Upon opening the packet, I noticed it was MLA-30+ instead of MLA-30 I ordered.

So, I have 2x MLA-30+ now.  I have been using the 1st MLA-30+ for about a week now, and it works great.  It pulled many DX sig. I have never heard before, or struggled copying with my long wire such as CFRX Toronto 1KW on 6070 and Zambia NBC1 from Lusaka Zambia, and TWR from Botswana ... etc etc.  It seems work better at nights.

There are times and signals that LW works better, so it is good to have both antennas.

Yes, I think it could be used as general RX ant. rather than just magnetic loop.  It worked quite well when connected to a random length of wire too.

The 2nd MLA-30+ will be used with larger and thicker element to cover the lower freq. better.

[RobRich]

The discussion inspired me to continue modifying the MLA-30. I removed the attached coax and installed a connector at the preamp. Now I can use RG-6 or whatever.

Linked below are a couple of pics showing the MLA-30 as a preamp for a YouLoop simply hanging on a kitchen chair near a sliding glass door. Worked about as expected for an indoor antenna here.

https://imgur.com/a/fGCz3Yk

Now to get the MLA-30 outside sometime. Maybe over the weekend.

[alpard]

Looks interesting. Let us know how it worked.

[kris]

     I wrote earlier about my impressions of using the MLA-30. A few words for this informative discussion.
- the cheap balanced amplifier used, has high self-noise and the input is not optimized for loop resistance
- powering the amplifier through the DC5V / DC12V converter is convenient, but it causes additional interference
There are publications on the Internet on how to improve these conditions.
- Amplifier voltage changes in the range from 5 to 12V did not cause a noticeable change in the noise level in the receiver. Maybe this is due to the noise level in my environment?
I haven't tried bringing the MLA to the garden yet, but I hope to significantly reduce the level of interference compared to the interior of the apartment.
The MLA 30 has a clearly directional characteristic, which is its valuable advantage and allows you to draw an interesting station from the crowd received on another antenna. For this reason, more advantageous than horizontal is vertical antenna polarization. The signal received in horizontal polarization was smaller than from directed antenna in vertical polarization. Practice shows that the polarization of the incoming radio wave changes during reception due to reflections from inhomogeneous layers of the ionosphere. For this reason, we can only talk about the advantage of one of these polarities.
   I rolled up a new loop of 5m long PEX / AL / PE  16 / 2mm sandwich pipe.
The new loop with a diameter of 160 cm improved MW reception and reception deteriorated around 15 MHz. It is difficult for me to say whether the antenna's efficiency has improved.
   General conclusion, if you cannot put up an external antenna, set up a cheap MLA outside the window.
   I was disappointed with the low signal level, hence another modification - loop tuning to resonance with an air capacitor (around 600pF).
 The large loop is coupled through a small coupling loop with a diameter of 1/5 of the large loop.
 A small loop is connected to the MLA amplifier. Now this is just happening, but not only good - noise has increased significantly. You need to work on the level of feedback between the loops and consequently the optimization of gain and noise level.
  Such a large diameter of the loop is inconvenient to turn it, so in the next stage I rolled it into two coils, obtaining a diameter of about 81 cm. I haven't had time to test this setup yet, but the tuning range and signal level have not changed noticeably.
   Tasks to be performed in the new year:
- install the MLA in the garden
- do remote antenna rotation
- do remote loop tuning
 If I do, I will write about the effects.
   P.S. The new MLA-30+ uses a different input amplifier and changed the power supply. .
         Did this reduce self-noise?
         Write what you know about it!

[redhat]

I bought one of the MLA-30+ about a year ago.  Compared to the 30' vertical in the backyard, the MLA-30+ is about 20dB noisier.  Signals that are discernable on the vertical are buried in noise with the loop.  The noise floor of the amplifier is just too high, and that is with a home made power injector, not the provided one.  I love the loop concept, but the front end needs work, and there are many solutions out there that I'm sure perform better.

...But for the price, it's hard to beat.

+-RH

[alpard]

I have put my MLA30 in the garden about 6ft above the ground, and it seems working a lot better (cleaner sounding and more signals heard).
I also have used different BIAS-Ts from the different active antennas such as Spectrum communication and MFJ.  They don't use the stepper voltage system in the BIAS-T. They use straight 12V input and output system.

The result was that, I was not sure. The MLA30 sounded a bit more cleaner and quieter, but not that much.  And DX signals? I don't think it made much difference.
So, I put the original MLA30 bias-t on.  The noise floor of antennas seem a lot depend on the surroundings and band conditions rather than BIAS-T.

But as said above, if I was living in a flat with no gardens or outside land to put wire or vertical or dipoles, this MLA30 would be the only antenna I would use.
It is not the best DX antenna on the market for sure, but it works. And it can hear some DX too depending on the band conditions.  And for the price and space it takes? It is a good value for money antenna that works.  It will work better for LW if the element is replaced with slight longer one.  But for MW and HF, it is good with the original element.  I especially like its performance on MW.  But on HF? I prefer my longwire and dipole.  They hear far more weak DX signals when matched with proper good baluns.
MLA30 will work far better, if it were rotated to the signal direction.
But seriously fort the money? Not a bad antenna.  It is easily worth five times the price. Not quite 10 times, but hey 5 times? A good deal for sure.