SDRplay compare mag loops: MLA30+ & Wellbrook loop
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- Опубліковано 6 вер 2024
- In this video Mike Harwood compares the popular MLA30+ magnetic loop with the Wellbrook ALA 1530N antenna at various frequencies using a single SDRplay RSPduo which allowed simultaneous spectrum snapshots of the 2 loops in action with real signals.
This is the third of Mike's antenna comparison videos.
Here's a link to the introduction to the series: • SDRplay testing active...
We can't guarantee what we will do next although we will always prioritise this activity around popular loop designers/companies who recommend our SDRs - that way both suppliers are on the same page when it comes to providing follow-up support to anyone following our recommendations for an SDR receiver plus antenna combination. We list our recommendations on the SDRplay "Antenna Suggestions" page on our website: www.sdrplay.co...
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The RSPduo is ideal for real time comparisons of two antennas as demonstrated in this video (fast forward to 5 minutes in): • Setting up SDRuno to v...
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A very big modification that needs to be done on the MLA 30+ is to replace the very thin and no so good coax that it came with. This modification is even more important than the copper tube. One can also use a much thicker copper tube. Their are videos on youtube on how to do both.
The all-new Wellbrook ALA1530LN should've been tested here. In April 2021 a new design was released with a 28dB gain amplifier for higher HF gain and improved LF sensitivity with IMDs much lower by at least 20dBs thanks to the JFETs and up to 16dB lower noise floor. Maybe next time.
The majority of MLA 30 buyers will use the stock thin steel wire loop that came with the antenna. I'm not sure how much of a difference the copper loop made in the results but this test should have been done using the stock, not modified, antenna.
Exactly!
doesnt make any diferance and if you increase the diameter noise increase with little gain you cant make silver to gold wellbrook
The difficulty I faced choosing the experiment is that the smaller thin loop will induce a smaller voltage across the loop in response to a signal, so performing the comparison with the wire loop will disadvantage the MLA30+ against the Wellbrook from the start. Overall, I thought it would be of greater value to equalise as many parts of the problem as possible (loop, power supply etc), so the observed difference are mainly down to the LNA performance. If people are happy with the MLA30+ when it is working at its optimum, they can then choose the set-up they want with some possible performance reductions. I accept that this is not the only way to have proceeded..
@@teunaydin By increasing the diameter of the loop, the amplitude of the signal and atmospheric noise are both increased, but the amplifier noise is largely unchanged, so the amplifier noise contribution becomes proportionally less important as the loop diameter increases. However, with a 1m loop, the amplifier noise is not usually a major factor for a well designed LNA like the Wellbrook. For a poorly designed LNA or small loops, increasing the diameter may reduce the SNR difference.
@@mikeh2909 I agree. It was the right way to do it, but the diasadvantage of the stock loop should be pointed out.
I own 2 mla 30's. There was a difference in signal strength between them that could not be tuned by the potmeter in the amplifier. Then I noticed there is also a potmeter in the bias-t. With that one I could tune them to have the same signal-strength. The components in both bias-t are not all the same, so it looks like there are more types of it. Both have a mla30+ sticker on them. One has a green led, the other has a red led but there a more differences in components in them.
the red led one is fake, real ones use green led only
I also tested the two types but I was mainly interested in weak signals for tracing RFI problems. I found that the signal to noise ratio was much better for the Wellbrook because its noise floor is much lower. This also explains why the MLA-30 fails to detect some of the weak signals as they are below its noise floor. Depends on whether you need the lower noise or the cheaper price. I also used the DUO and it did a great job of allowing realtime comparison. It is fun playing with the diversity mode to show which signals are better on one loop versus the other.
The TL592B used in the MLA30 and presumably the MLA30+ is described as a differential video amplifier and is not designed as a particularly low-noise amplifier and doesn't use particularly low noise techniques (apart from avoiding feedback resistors from o/p to I/p). The specified noise isn't broken out into current and voltage noise components, but is just quoted as a 'broadband equivalent input noise voltage' between 1kHz and 10MHz and is 3uV. This doesn't indicate a focus on intended low noise applications. Having said that, I am not aware of a better single IC solution with an integrated 50 Ohm output driver that are probably important considerations for this price point in the market.
Thanks for the comparison. I found the interference on the MLA 30+ is improved somewhat using a power bank instead of mains power. Having said that it was too noisy for me despite trying various locations. I came to the conclusion I prefer building passive loops or the YouLoop 👍🏼
Yeah, the noise floor is lower if using a linear PSU instead of one of those switching phone chargers, about as low if not slightly more than using a power bank (power banks often use buck conversion to output the voltages for USB, which can cause a lot of interference or noise in the line). I've been lucky in the few power banks I've bought have been relatively quiet, especially when compared to a switching Phone charger.
I do have a YouLoop, I only really use it when I don't have to deal with a lot of nearby interference.
noise even lower if you use battery pack instead of power bank dear franco:)
Thanks a lot Mike for testing these 2 antennas. In the near future I want to buy a Malahit DSP SDR v3 receiver and will connect a loop antenna to the SDR receiver so this was/is very helpful, thanks again...
I found the MLA-30 to be very similar also with the MFJ-1886 loop antenna. The MFJ-1886 loop antenna did outperform on Longwave. I would like to see a comparison between the MFJ-1886 versus the Wellbrook. Thank you for posting this video. Have a good day.
Mike Harwood appreciates all the feedback, but for some reason all his comments have disappeared! Please keep your comments coming and we’ll get Mike back on stream ASAP
Hopefully fixed now...
The interference and higher noise floor is usually due to using a noisy USB phone charger or other noisy power source.
The noise floor can be lower if you use a linear PSU, or a battery, or a good (non noisy) power bank. The interference you see if oftentimes due to a noisy power source pumping trash into the bias tee which puts it into the amp.
Another thing with the MLA-30 is its using pretty low quality coax, upgrading the coax helps a bit as well.
All true. In addition the single IC solution for the MLA30+ probably has several times the level of input referred LNA noise of the Wellbrook which uses discrete transistors and transformer augmentation (Chris Trask invention) on the 1st stage.
Excellent the best analysis ı have ever seen up to now for 2 ant
Thanks!
Very very nicely done,sir. I have to admit I can't afford the Wellbrook so went with the MLA+. I'm a tad annoyed with the huge price difference for just a few electronic components used to improve the Wellbrook's performance. Stinks of money grubbing and not caring a whit for the more mainstream user.
Perhaps the title of the video should have said Modified MLA30+ as you're not using the steel wire that forms the stock loop antenna. So with this modification its most likely better performing using the copper tubing, it's an easy enough adjustment to make and certainly it's hard to justify spending 6-8x for the Wellbrook with these results. The original MLA30 claimed to start band coverage at 100kHz but this was found to be a false claim in practice so it was changed to starting instead at 500kHz for the + version. I did notice that noise floor was lower on the Wellbrook overall so this is the difference for DXers to pick out the signal from the noise or have it lost in the noise. The RF Gain was lowered on the Wellbrook for MW, not sure why this was done, unless there was some overloading? Also, is this the ALA1530LN? If so a newer version of this loop was released in April 2021. It would have been interesting to compare the stock MLA30+ (without modification) and the newer 2021 Wellbrook which now has it's amplifier gain increased to 28dB. Overall a good comparison and proves the Wellbrook certainly isn't 6-8x better than this modified MLA30+
No antenna is 6-8 times bether than another. A slight difference for Dx can be huge on results. That’s the point.
use WSPR (or other digital modes) reception on all the bands (2200 thru 6m) and compare the reception quality indicators provided by the software to do the comparison. Takes all the guesswork out of comparing things.
Awesome comparison. It really shows the MLA30 is a good buy. Thanks for sharing.
Not much good for your hopes of catching some LW DX though, Tom.
@@tonymagnier9846 So far you are correct. :(
@@hamrad88 in lieu of a Wellbrook you could contact Larry Plummer about his W6LVP loop for LF/VLF DX, he's very helpful.
@@tonymagnier9846 Thanks. Will try.
Certainly an interesting comparison, I am using an MLA-30 for diversity receive with my FTDX101MP, subjectively it does not do well on the 160m amateur band but that is with the stock wire loop. I had put it to one side a few years ago, thank you for the video, I shall do more experimenting with it.
Have you guys ever tested various coax cables, with all other things being equal (as much as possible)? Cable costs can vary widely, just like antenna costs. It would be interesting to see if expensive cable is worth the extra cost.
I haven't done much dedicated AB comparison with cables, or at least not in a structured way. For sub-30MHz RX use, the loss in dB per metre is very small and I only tend to use lengths in the 10m to 20m range. For my comparisons, I try to make the cable as good as I can (within reason), so it has an insignificant influence on the overall antenna performance - I want to compare the antenna rather than the cable, which I know is the opposite of what your question suggests! So, to this end, I have used RG58 BNC cable from a reputable communications company (not a cheap supplier) and H155 SMA cable. So, to answer your question, no, I have not made a structured cost/performance comparison between different cable types.
Wellbrook compagny is close now.
I would be interested in how the loops perform against a local noise source. Perhaps a noise source could be constructed to simulate the sort of e-field noise encountered in urban housing. It would also be interesting to see how deep the null is on the different loops. I’d expect that these two parameters might discriminate between the better constructed and less expensive antennas.
Thanks for doing these videos!
I wish I could buy the Wellbrook loop.
Brilliant video its given me a great insight into how these antennas work.
Does the MLA30+ have a decent Null ? I need to null interference coming from a neighbor. I'm currently using my Alpha Antenna Magloop for RX but I can't leave this one outside permanently.
I didn't perform a comprehensive study of this, but I was certainly able to null out interference by over 10dB (by memory). The MLA30+ has a fairly high input impedance compared to many magnetic loops because it uses a standard TI video amp as its front-end active circuitry. It will therefore receive more of the near-E field than (say) a LZ1AQ which has a very low input impedance and therefore a large mismatch to the short dipole impedance of the loop.
It would be interesting to see a side by side comparison of various loop types like singe loop, 2/4 crossed parallel loop etc .2 or 4 crossed parallel loops. Are they really perform way better?
Hi Team, thank you for that great comparison of the antennas. I just have one question. In your plots I recognize that you have different 'GAIN Level'. How did this influence the result? e.g. 40m band plot1. MLA30 with 30dB while the WB with 45dB. This is large difference but not sure how this influences the result. vy 73 !
Hi Tom, the procedure that I used was to set the RF gain slider to the highest level that I could without 'overload' bring reported by SDRuno. Generally this meant that the slider was at the maximum. I then had the IF AGC enabled for each tuner, so SDRuno could optimise this for best performance for each tuner. I have found that this should result the best RX configuration for each antenna, even though the actual combined gain of RF + IF would not be the identical for each tuner - as you noticed. I think this approach makes sense because there is no reason why the LNA outputs for the Wellbrook and MLA30+ should be the same, and this results in different signal inputs at the SMAs that needs allowing for somewhere within the RSPduo. I'm sure that the difference in output from the two loops' LNAs does influence the results to some degree. I prefer to apply the gain at the antenna rather than the tuner because it reduces the impact of feedline induced interference - the bigger the signal from the LNA, the more it dwarfs the feedline interference. However this relies on the LNA designer being able to produce a 1-30MHz HF amplifier with better noise & IMD performance than the very, very Wideband 1KHz to 2GHz amplifier in the RSPduo. I trust Wellbrook more than MLA30+ in this regard. So in summary, I do expect the difference in Loop output and consequent tuner gain to have some impact of the results, but I tried to make each loop work at its best in order to give a fair comparison of each loop. - Mike H.
@@Mike-H_UK Hi Mike thanks a lot for the quick, very detailed and competent answer. I have the MLA+ but I guess I need to mod/tune it with a better loop maybe you-loop. Thanks a lot and 73!
@@tomhelo4523 I don't know if your MLA30+ is the standard product, but there are also some improvements to be made that are low-cost and quite effective. Using a larger loop to make it the same diameter as many of its competitors (about 1m) helps, as does using a slightly thicker wire/tube. Also some people report improvements by upgrading the SMA cable from the factory supplied one. All worth a go before spending too much...
No site Aliexpress tem o modelo K-180wla, seria um substituto para o MLA30+ vendido também neste mesmo site ?
It was going OK until point 1, initial test summary (5'), which is useless: no point testing outide the antenna's range. It would have been better to have the loops out in an open, RFI-quiet environment, however; with the strong directionality these loops typically exhibit, the proximity of the building on the left is a concern, at least to a remote observer of the work done. This could have been covered by swapping positions of the loops and seeing if there was a deterioration in the Wellbrook as a result.
I have 2 MLA 30+ antennas. The Biasing Tee powers up fine on a USB plug in power adapter but when I try and power it through a portable power bank the power cuts off after a few minutes. This happens with both antenna Biasing Tees and with several different portable power banks different power cords. I would like to use the antenna for portable
use but cannot power it. Is this normal or do I have two defective antennas.
I'd say this is normal. Some power bricks would turn themselves off when no data flow is detected. I have tested a dozen of power bricks with MLA-30+ and this is my conclusion.
It's a cut-out on the battery bank; entirely normal. You can build a circuit to burn a small amount of additional power, so that it stays on. SotaBeams sell one intended to stop this happening with their WSPRlite transmitters, which draw a tiny current.
Replacing the supplied loop certainly improved things. Thanks again for posting the close up images on the Facebook group. I wonder if I could know what ferrite you use in your den? There seems to be so much contradictory information out there! I've seen recommendations for type 31 and type 75 for lower frequencies. I'm mainly interested in 0-30Mhz including transatlantic DXing. I've ordered one of the USB cables you recommended in your video. However they don't specifically the frequency range it projects against. Sorry for the ramble! Peter
Hi Peter, I tend to use a T130-2 toroid ferrite with coax lines and wrap a few turns of coax through the hole near the cable connector. For clamp on ferrites, I have historically used some cheap generic clamp-on ferrites from Amazon. These will almost certainly be lossy at a few MHz upwards, so will be good at killing external RF fields around cables. You'll probably get as many different options as people that you ask, so I would recommend buying a few different types and experimenting. I have found the Tripp Lite USB cable to work better than rest of the random collection of other USB cables from discarded printers, cameras etc, and I haven't seen a thorough spec either. The Tripp Lite has a solid connector and thick cable screen/shield that are inherently good for reducing interference. The ferrites will reduce currents on the outer conductor that can cause interference. I use it more because the cable uses good design and construction techniques and has had a degree of thought applied to its design, rather than because I have seen a great spec that has won me over.
Vraiment intéressant , merci.
Why not do the comparison of the two aerials as they come “out of the box”? Replacing the solid wire with a copper tube on the MLA makes this a bit meaningless in my mind.
The MLA was just an amp "out of the bos" I believe
Mike's voice is difficult to listen to. Alot of whistling makes his voice sharp and annoying.
Appreciate the info but your audio needs work. A de-esser in the least. It's torture on the ears.
Point taken. I was experimenting with a new mic that didn't make the grade. I will upgrade for future videos!
I cannot under any circumstances see how the price of some of those loops are justified, it seems to me than over £200 is just a rip off and as for those at £1000, I wonder how many they sell
change microphone please
Point taken. I was experimenting with a new mic that didn't make the grade. I will upgrade for future videos!
The distortion in your voice is so bad that I stopped listening one minute in.
Almost un-listenable because of his microphone.
Point taken. I was experimenting with a new mic that didn't make the grade. I will upgrade for future videos!