MLA-30 active loop antenna

[A.Z.]

So what is the next cheapest Antenna in comparison who is better and affordable to?

Better than what ? If you're referring to the stock MLA-30, with its noisy bias-t unit and the other issues, then even a passive loop may beat it, but as usual, there's no "absolute best antenna", otherwise everyone would just be using that and nothing else; then maybe I misunderstood your question.

[Lord of nothing]

Well I mean a better constructed one who give even similar performance by lower noise and so on.

[A.Z.]

Well I mean a better constructed one who give even similar performance by lower noise and so on.

I see... well, in such a case, call me crazy but I still prefer "self built" ones  as for loops the Wenzel "loopifier" (which I built in several samples - for friends too) is a pretty good one, it uses the same TL592 IC, but being tuned and using a decent bias-tee design, it overcomes IMD and noise issues and gives very good results, then there are the loops from Matt (KK5JY), even if they are passive, they offer incredible performances, the "SRL" is the easiest to put together, and the "LoG" offers incredible performances on the low bands (40 meters and down), then there are a bunch other antennas I tried, but in general, when it comes to antennas and in particular RX ones, ensure to care the whole system, this means using decent coax (given you won't be using openwire) and good choking and grounding; in the MLA-30 case, this doesn't suffice since, as I already wrote, the antenna design falls short on a number of aspects, luckily those are easy/cheap to fix

[vinlove]

In this side by side test, MLA30 and the Wellbrook, the stock MLA30 was quieter?

[A.Z.]

And that should be a comparison ? Again, if you are satisfied, go for it. I'm not, so I believe it needs to be modified, please avoid trying to convince me that the stock (as it comes) MLA-30 works well, it doesn't, and I write this from direct experience and comparison ( and then it's easy to see why, looking at the bias and preamp circuits), again, if you are satisfied with the stock one, go for it, but don't try convincing me, thank you

[Lord of nothing]

For me the stock MLA-30 working better than a plain copper Wire. I would say for beginner who want see if the could receive anything (maybe because a damn neighbour in an Appartmentcomplex use Powerline).
@A.Z. for someone who have Tools and maybe a Basement, Shack,... or what ever its easy to build. Sadly I have just my Home Office with a lot of Server inside who I want to avoid anything who could produce dust or a dangerous atmospheric.

[A.Z.]

you wrote about other antennas and now they're just "copper wire" ? Are you playing some kind of joke or what ? As it is the MLA could be easily beaten by a simple wire loop or linear loaded dipole ... correcly installed ... oh well, maybe I'm just an old fart fighting windmills ... deep sigh

[vinlove]

And that should be a comparison ? Again, if you are satisfied, go for it. I'm not, so I believe it needs to be modified, please avoid trying to convince me that the stock (as it comes) MLA-30 works well, it doesn't, and I write this from direct experience and comparison ( and then it's easy to see why, looking at the bias and preamp circuits), again, if you are satisfied with the stock one, go for it, but don't try convincing me, thank you

No no, I am not trying to convince you about anything. Why should I?
I am just saying that HF and MW RXing is not that simple topic.
You just think that noise floor is low on a antenna, and blindly believe that it works best for you, but
I am trying to say that there are the other factors involved in this game.

The point of your having a antenna is that, so you could hear the signals not trying to get low noise device, so that
you could meditate or fall into trance or something.

You know that a dummy load is quiet? Yes, super quiet and will give you low SWR 1:1, but
it cannot hear the signal you are wanting to hear.

MLA30 might be a bit noisy, but it pulls the DX signals from the air and you could hear it on your radio?
And you must choose to go for MLA30, not a dummy load. That is just my point.

Whether it is a stock or not, it doesn't matter. The matter is, can it hear the signals from South America
and the Far East and South Pacific running about 10 kW or lower? Well if you can, it is a good antenna for you.
If not, sorry mate, your antenna is poor be it modded or not, be it expensive or not.

[Lord of nothing]

Well I am a beginner so its not that bad for me.

[vinlove]

Show me your logbook or list of DX signals you heard on your radios, and I will tell you how good your antenna is.

[A.Z.]

Show me your logbook or list of DX signals you heard on your radios, and I will tell you how good your antenna is.

Not sure you were asking me, anyhow, I tested the MLA-30+ after the bias-tee and preamp modifications, to do so I ran a test using the FT8 digimode for about 8 hours, and the received spots were uploaded to https://pskreporter.info which then generated the following map



not special but not bad, either; consider that before the mods, running a similar test, the MLA-30+ picked up much less stations (about 1/2); that said, even with the mods, the MLA-30+ works decently well from 7 MHz down, while going up in frequency its performances degrade very quickly; not a "super antenna" (my short LLD beats it hands down all the time), but if one has limited space I believe that, once modified, the MLA-30+ may be a good choice

[edit]

As a note, I didn't (yet) add the transformer between the loop and the preamp, and the antenna doesn't show noticeable nulls, I suspect it's due to the input mismatch, so adding the transformer may probably improve the nulling ability which, as is, is almost non existent, also, lowering the gain trimmer inside the preamp helps quite a bit reducing IMD and lowering the noise floor which in turn allows to have better reception (even of weak signals)

[A.Z.]

The point of your having a antenna is that, so you could hear the signals not trying to get low noise device

I think you're missing an important point; if the noise floor, due to a bad preamp or feedline is high, weaker signals will get lost in noise, so you will loose them, that's why it's a good idea trying to reduce the antenna system (by system I mean the whole setup, from the rig to the antenna, including feedline and grounding) noise, by the way, you can't reduce atmospheric noise, but for sure you can reduce common mode noise, place the antenna as "free" and far away from the local "noise cloud" (or "elettrosmog" if you prefer) as possible and minimize the noise introduced by whatever preamp, and this will improve reception, especially if you're hunting weak signals

[vinlove]

Sorry but FT8 is not interest of me. Never have used or tried that mode.
So, I cannot tell you how effective your modded MLA30+ is with the DX map.

If it were BCL DXing list, certainly it is impressive. But FT8? Is it not some digi mod?
For digi mod, I would prefer using Skype or some phone chat apps, and they connect the whole
world without any external antenna on the phones.

I am only interested in the traditional mode which are AM, SSB and CW and maybe FM in BCL.
Because this BCL SWL activity is a traditional communication activity.

Anyhow, on the noise floor issue, I am not sure if quieter antennas are better. I would say yes and no.
Sometimes it is good, if they can receive the weak signals you want to listen to, but some antennas
are just queit and deaf, and they cannot hear the signals either.
So, I wouldn't say the noise floor figure is the criteria for good antenna.

On HF and MW, I wonder if you ever get away from the noise on the band.  It is inherent in the bands.
Maybe multi element beams or log peoridic yagis will give you low noise and highest SN ratio.
But they are not practical for MW and HF bands up to about 14Mhz.

And in real RXing environment, as I have said before will say again, there are many other factors affecting
the noise on your radio. Your RX antenna is just a receptor of the noise, and your signals are just another
type of noise.

If you are in Europe, tell me how well you can hear the low power transmitting stations in AM from South America
South Pacific and Far East Asia and Afria, and I will be able to tell you how good your antenna is.
Not FT8 or some new digi mode, because they are not strictly analogue radio signals as such.

[A.Z.]

Sorry but FT8 is not interest of me. Never have used or tried that mode.
So, I cannot tell you how effective your modded MLA30+ is with the DX map.

I don't like FT8, but I find it to be pretty useful to check if a given antenna/modification works, also since FT8 uses low power

Anyhow, on the noise floor issue, I am not sure if quieter antennas are better.

Antenna system, not just antenna, it includes the antenna, feedline, grounding... see, the point which you seem to be missing is that whatever RX antenna system should be optimized to "set the noise" that is, aside from natural noise, the system shouldn't introduce much more noise than the one internally generated by the receiver, such an antenna won't be deaf at all, on the contrary, it will give you much better performance, especially for weaker signals, it isn't about "how strong" you receive, but about signal to noise ratio

On HF and MW, I wonder if you ever get away from the noise on the band.  It is inherent in the bands.

Just to make an example, using my LLD (Linear Loaded Dipole) the average noise floor is between -110 to -130 dB, using the "stock" (unmodified) MLA-30 the noise floor is between -90 to -100 dB; this means that weaker signals will be unreadable with the "stock" MLA-30 since they'll get lost in the noise; modifying the MLA-30 I was able to bring the noise floor down to around -110 to -120 dB which, while higher than the LLD one is a good result, and now the MLA can pick up signals which it couldn't before and which the LLD pulled in w/o problems; see my point now ?

If you are in Europe, tell me how well you can hear the low power transmitting stations in AM from South America
South Pacific and Far East Asia and Afria, and I will be able to tell you how good your antenna is.

Well, one of the stations I picked up last fall (in September if I recall it correctly) was the Neumayer Station in Antarctica, signal was faint since they use a low power transmitter, but was totally readable, by the way, there's no problem in picking up broadcast stations, by the way, depending from time and propagation, although I'm more interested in other types of signals

[vinlove]

But, you know, the noise floor changes with time of day too. For example, at night, I hear a lot better with MLA30, and the random wire in the garden is very noisy with even break through from MW it is useless.

During the day, the random wire hears a lot better. All the noise disappears, and gives good reception.  The MLA30 still works fine, but it is more noisier than at nights. It also depends on the signal that you hear.  Sometimes MLA30 works far better, and other times the RW hears far better.  I couldn't pin down clearly, one is better than the other, just by measuring the noise floor coming up on the graph at just one point of time? It would be wrong conclusion to say either this one is better than the other.

[A.Z.]

But, you know, the noise floor changes with time of day too.
For example, at night, I hear a lot better with MLA30, and the random wire in the garden is very noisy with even break through from MW it is useless.

You are confusing the environmental noise floor, which depends from a number of external factors, with the antenna system "intrinsic" noise floor (which includes, for example, the nasty common mode noise) and with the local "electrosmog", while there's nothing one can do about propagation and atmospheric conditions, there's quite a lot of things one may do to reduce the "intrinsic" noise floor to a minimum; hope you'll finally understand what I'm talking about

[vinlove]

But, you know, the noise floor changes with time of day too.
For example, at night, I hear a lot better with MLA30, and the random wire in the garden is very noisy with even break through from MW it is useless.

You are confusing the environmental noise floor, which depends from a number of external factors, with the antenna system "intrinsic" noise floor (which includes, for example, the nasty common mode noise) and with the local "electrosmog", while there's nothing one can do about propagation and atmospheric conditions, there's quite a lot of things one may do to reduce the "intrinsic" noise floor to a minimum; hope you'll finally understand what I'm talking about

Everyone who uses RX antenna is under the environmental factors.  What is the point of emphasising "intrinsic" character of the a antenna, if your environment is RFI farm?
I think it is time for you open your eyes and see the real picture of the RXing = what DXing on MW and HF bands means in the real world.  Please don't get blinded by "intrinsic" noise floor garbage. RXing for MW and HF DXing means you and your radio and antennas are always under some environment, and propagation and the band condition.  You are not going to be DXing in laboratory setups. None of us are, unless you are writing some commercial reviews of the products for the media or magazines.

[A.Z.]

I think it is time for you

Ok, I'm giving up, goodbye and happy new year.

[vinlove]

I think it is time for you

Ok, I'm giving up, goodbye and happy new year.

You can also lower the noise floor figures by just lowering the input voltage on any RF amps too.
Happy New Year to you

[vinlove]

I have a dipole, and longwire with ATU and the stock MLA30, and the stock MLA30 is the best performer for the weak DX signals 90% of time. So I just let it keep working until something else better turns up.  Will try different bias-t (both modded and from more upmarket units) in the near future, and will update here with the results of course.

[vinlove]

$330 Wellbrook antenna vs. Cheap balun and wire comparison.

[ZigmundRat]

I’m glad you made the comments about this being *your* experience at *your* location with *your* equipment. It’s important to understand that there are so many variables affecting HF signals it becomes very very difficult to draw conclusions between different installations at different locations even when using identical equipment.

It was interesting to see that the SNR didn’t really change much in most cases. You appear to have significant man made noise at your location, and this is where the different characteristics of the two antennas should be evident. This noise is limiting your ability to ’hear’ on either antenna. The key thing about the loop is its ability to null out noise sources by changing its orientation, not that it is an ‘intrinsically quieter antenna’. If you were to rotate the loop to minimize the man made noise, overall your performance would improve because the SNR would improve. This could mean that the signals are ‘weaker’ but the noise is weaker still and that’s the point of the loop. It’s not about absolute signal levels.

I would expect that the Wellbrook and the MLA30 would perform similarly if mounted identically (height, orientation, feed line, etc.) even if the no signal noise floor changes due to the different preamps. It’s all about signal to noise ratio.

[vinlove]

Great points ZR.  That was what I have been trying to say to AZ all along.
A simple NF figure is not the only criteria that a antenna is better than the other antennas.

There are so many other factors affecting the performance, and the main point of having antenna is to be able to receive the signals, not having quiet noise floor.
It is good if low NF can aid in SNR, so that it makes the weakest signal audible.  But often from my experience, the low NF antennas do also kills and buries the signals too, and
this is the problem with the quiet antennas. 

I think above test is not quite fair either.  Because the real test of antennas is when trying to copy the weak signals buried in QRM and QRN.
Trying out the testing antennas by listening to some very strong signals copyable with a portable radio with whip cannot be good testing.

Again there are so many variables on that testing too, so unless all the factors are identical (even the band condition, which can change in seconds ), it couldn't be a true fair testing.

[vinlove]

Just to update my own experiments with MLA30.

I have tried a few different B-Ts from commercial active antennas and loops. They are from AOR, Spectrum Comms UK and MFJ.
When replaced the MLA30 B-T with each of those other B-Ts and received RNZI on 11725 kHz for durations of few hours.

MLA30 with each of those different B-Ts sounded with hint of quietness on reception than the stock B-T, and in the case of AOR B-T, it even gave slightly improved SNR.
But there was no significant difference in the reception quality and readability.

RNZI signal is one of the toughest to copy coming from most distance location from me, and it still all sounded very weak no matter what B-T was paired with MLA30.

When switched over to my lonwire with ATU in the garden, it was a lot better copy than MLA30 with any B-Ts.
So is it worthwhile to replace the MLA30 B-T?  For slight improvement in noise, yes.
But overall RX readability and intelligibly? I doubt it is making huge difference.

More critical factor seems, , the location of RX (Height and RFI situation) and more well matched antenna to RX.
The DXing capability antenna tests should be carried out for RXing the most tough signal to copy in terms of weakness and QRM and from most distant location.
There is no point doing antenna tests with generally strong signals coming from same continent or TXing with mega millions of kWatts, which can be copied with any radios with whip antennas. And the NF graphs and figures in lab setups? It tells about maybe the amount of noise generated by the antennas themselves, but not the capability of DX reception? Just my 2 cents. cheers 73s.

[A.Z.]

oh well

https://www.hfunderground.com/board/index.php/topic,69273.0.html

deep sigh

anyhow, I'm collecting all the infos details and pics, so may have something ready in a while, all I can say is that the high noise floor of the standard antenna is confirmed, luckily there are some workarounds which can turn it into a pretty decent antenna... more later

[edit]

Here are a couple screenshots, the 20m bands was almost dead when I took them, so they are a good example, the first pic shows the noise floor of the LLD (Linear Loaded Dipole)



while the second one shows the noise floor using the MLA-30+ with its standard bias-t unit, both antennas were placed outside at almost the same spot and height



now, while some increase in noise floor is to be expected since the MLA is an active antenna, while the LLD is a passive one, the level of noise which can be clearly seen is, in my opinion, far too high and in particular if we consider that the MLA is a loop antenna