Many thanks to SWLing Post contributor Don Moore–noted author, traveler, and DXer–who shares the following post:
Two Portable Antennas for Remote DXing (Part Two)
By Don Moore
Don’s traveling DX stories can be found in his book Tales of a Vagabond DXer [SWLing Post affiliate link]. If you’ve already read his book and enjoyed it, do Don a favor and leave a review on Amazon.
In my initial comparison of the PA0RDT mini-whip and the MLA-30+ MegaLoop, the mini-whip performed best on medium wave and the lower shortwave bands, while the loop worked better on the higher bands. But, I wondered, why should the MLA-30+ be restricted to that small steel loop? The wire loops I use with my Wellbrook ALA-100LN typically range from twenty to fifty meters in circumference.
I threw a twenty-five-meter wire over a tree branch and formed it into a delta with the MLA-30+ in the bottom center. Remember, I was testing in the northern Chicago suburbs. My SDRs were completely overloaded. Medium wave was useless and I had strong MW stations all over the shortwave bands. The MLA-30+ doesn’t have the same strong-signal handling capabilities as the Wellbrook. And there are a lot of strong medium wave signals in the Chicago suburbs.
So I took that wire down and replaced it with a loop of twelve meters circumference.
That did the trick. I had lots of signals on medium wave without the overloading. Here’s what the upper end of the MW band now looked like with the MLA-30+.
For comparison, here’s the same wire loop using the Wellbrook ALA-100LN. The Wellbrook has a slightly lower noise floor but otherwise the signals are about the same.
Out of curiosity, I replaced the Wellbrook power unit with the Bias-T from the MLA-30+ but left the Wellbrook antenna head unit in place. With this hybrid setup there’s no visible difference with the full Wellbrook.
I was satisfied with my findings but I still wondered how much wire the MLA-30+ could handle. A few weeks later I ran some more tests in Kansas, where I knew the dial wouldn’t be as crowded. The MLA-30+ easily handled a 25-meter delta loop without overloading.
Two weeks after doing the Kansas tests I was at a DXpedition in rural western Pennsylvania. The MLA-30+ worked fine with a 40-meter circumference loop, other than being a tad noisier than the Wellbrook with the same wire. So how much wire you can use with the MLA-30+ components depends on how strong your local medium wave stations are.
Findings
From the SDR images above it would be easy to conclude that with the right length of wire an MLA-30+ is just as good as a Wellbrook ALA-100LN even though it is significantly cheaper. But that’s not the full picture. Back in the 1990s my Drake R-8 cost about three times what my Sony ICF-2010 did. All other things being equal, I would say that 95% of the DX heard on the Drake could have been heard equally well on the Sony. I wanted the Drake for the other five percent.
I have no doubt that if I did a very careful head-to-head comparison of the two units under serious DX conditions on the same wire that the Wellbrook would get things the MLA-30+ couldn’t. But I suspect the difference would be around that five percent mark. I’m willing to accept that tradeoff for an effective cheap light-weight travel antenna. And the MLA-30+ is like having two antennas in one. I can use it with the steel loop in limited space situations or with a larger wire loop when I have access to some garden space with a tree. Together, the MLA-30+ and the PA0RDT make the perfect DX travel antennas.
The only thing I didn’t like about the MLA-30+ was that pre-attached coax cable. It’s not the best quality and I’d rather carry my own cable. I’m not very handy with a soldering iron in tight spaces but at our recent DXpedition my friend Bill Nollman replaced the coax with a BNC jack for me.
The MLA-30+ now looks like this when connected to a wire loop.
Finally, I should address powering the MLA-30+ via USB. While it can be connected to a spare USB port on your laptop, I found doing that sometimes introduced a tad more noise. Instead I’ve been using one of those battery packs used for recharging cellphones. Mine is rated at 6700 mAh and it can power the MLA-30+ for over 48 hours before needing a recharge. But be sure to test yours before doing any serious DXing. I’ve read that some power packs have a minimum required power draw and will automatically shut off if the draw is too low.
Another Option?
While I was finishing this article I heard about another option from my friend Guy Atkins. This antenna is a combination of the YouLoop with a low-priced Chinese made clone of the LZ1AQ amplifier. Some users say it’s better than the MLA-30+. Guy says it works well on shortwave up to 16 meters but he hasn’t tried it on medium wave. Guy says it’s a “low price, good value” antenna. I’m traveling in Southeast Asia for the winter but will definitely have to try this antenna when I get back to the USA. So maybe there will be a follow-up article next summer.
Links
[Note: Amazon links are affiliate and support the SWLing Post at no cost to you.]
Info on ordering a quality PA0RDT from Roelof Bakker. (Other cheaper versions have had issues with quality control.)
https://dl1dbc.net/SAQ/miniwhip.html
There are various versions of the MLA-30+ and the original MLA-30. This is the version that Mark Taylor recommended and that I bought.
There are numerous YouTube videos on using and modifying both versions of the MLA-30+. This one shows how to replace the coax with a BNC jack.
https://www.youtube.com/watch?v=OAqh2Lawwdc
Here’s the Amazon link for the YouLoop/LZ1AQ antenna that Guy has.
And the same antenna on Ali Express.
Andrew,
I did some experimentation with loop orientation that might be of interest: https://swling.com/blog/2024/12/here-we-go-loop-de-loop-in-which-your-humble-correspondent-tests-a-hypothesis/
Sounds to me like I might want to experiment with hooking my horizontal room loop: https://swling.com/blog/2021/06/jock-designs-a-horizontal-room-loop-to-cope-with-reception-issues
It also makes me wonder how to MLA 30+ amp and a wire loop would work as a loop-on-ground.
And I think Don’s comment about 95% performance is spot on: it seems that in almost every hobby, a good medium-price purchase will get you 95% of possible performance . . . and the remaining 5% will cost you as much as you care to spend . . . and then some.
Good to hear from you again!
Cheers, Jock
Here’s another antenna I successfuklly used, start with these
* 9:1 voltage balun (isolation transformaer)
https://www.nooelec.com/store/balun-one-nine-v2-barebones.html
* FM bandstop filter
https://www.nooelec.com/store/distill-fm-broadcast-fm-filter.html
* LANA HF (50kHz-150MHz LNA)
https://www.nooelec.com/store/lana-hf-barebones.html
the FM Bandstop is useful in Europe, in other places one may need the AM BCB bandstop
https://www.nooelec.com/store/sdr/sdr-addons/distill-am-broadcast-am-filter.html
but the purpose is the same, that is, cutoff/attenuate some flamethrower stations to avoid overloading the LNA
at this point just enclose everithing in a suitable waterproof enclosure, connect the 9:1 to a wire loop, and at the opposite spot (from the 9:1) break the loop wire and place a 550 Ohm resistor, the latter will act as a termination for the antenna and keep a good match over the whole operating range; give it a spin; it’s worth, mind me 🙂
About the MLA-30
https://youtu.be/RvXsywLbi9k?si=vIaycoy2hZk-0bOn
Add this circuit
https://www.arrl.org/files/file/QEX_Next_Issue/Jan-Feb2018/Steber.pdf
tò a youloop antenna (connect It tò the transformer) and the result Will Blow off whatever wideband loop 🙂
Picked up a PA0RDT mini-whip for a friend south of the border who found it cheaper to ship to Canada — and he will pick it up in January….
Funny that they call it a “whip” as it is a plastic encased…. module… for lack of a better name.
Compared to the Wellbrooks and LZ1AQ’s that I have here — and the Thomas Seeger LN Vertical…
The PA0RDT was a toy…. little more than a noise detection unit… consistently 10-16 db below my other “professional” Low noise small aperture loop products…
I will suggest that my friend “Larry” just put down the expenditure to “experience” and I will provide him one of my surplus LN Small Aperture loops so we can move on.
On the subject of popular products “cloned” — I get that… in my Lab I have made numerous LN LZ1AQ and ALA100LN amps for personal use… NOT for sale… It is a fun exercise — and yes, sadly, The Wellbrooks have all been reverse engineered…. sad that the Wellbrook product like did not continue…
73 All !
Colin, How about writing an article telling us about those LN Small Aperture Loops? And show us some real examples of what the signals look like, as I did in this article. If you can show me something better I will be very happy to adopt it and tell the world that it is better. As to your friend’s PA0RDT, I beg to differ on it being toy. In 2016 in Colombia I made about 15 hours of SDR spectrum recordings of the MW band with a PA0RDT. When I later went through them I found over 400 stations from 20 countries. I don’t call that a toy. Sure, there are antennas that would do better, but do they fit in my suitcase? Please, tell us about those antennas you are referring to so that the rest of us can learn. – Don Moore
I think its a real shame when well-known members of the hobby take to recommending shameless knock-offs of others’ work. Both the YouLoop and LZ1AQ amplifiers are still in production and for sale (and inexpensive, as well), and their designers do not get any benefit from these rip-off products. The overall benefit to the hobby is questionable as well. I’m actually surprised its taken this long for clones of the LZ1AQ design (albeit an older version) to become available, as its an excellent product. True, shipping to the US is suspended due to the tariff debacle at the moment, but that shouldn’t punish the research and risk he’s put in to offer his products for sale. The real product is at https://active-antenna.eu/amplifier-kit/.
Hi Don,
Thank you for the review. As I can see in your screenshots, the MLA30+ has a noise floor that is 12 dB higher than the Wellbrook’s. That’s two steps on the S-meter. I can also detect some ghost signals. In other words: The MLA-30+ receives more stations. Just kidding — it’s not a serious MW antenna in my opinion.
Tom DF5JL
These antennas are easily packable and make for a low noise and stealthy setup. I tried adding a larger aperture loop in the past but found the performance lacking enough that the Wellbrook was a lot better.
The past few year my experimentation for a travel set up and also to feed a Kiwi SDR had me revisit the clones.
I was pleased with the results and have been testing out various wire lengths and have also found the clones to be better than before especially with improved overloading.
Amazon has some 20db ampflifier LNA boxes that are excellent to increase the signals from these small loops as well.
If you replace the Sony 2010 with the loops and a SDR Play or Airspy, you will have room in your carry on for an extra pair of shoes and extra underwear and for a QRP rig and battery.
Be light but still have high performance in a set up that fits in a Topo Design pouch in your backpack.
Its a lot of fun deploying a 1m loop on a stick or stretching the wire out across some trees and tuning around looking for interesting listening targets.
John ve3ips
What a great time to be enjoying our hobby!
John, if you want tò discuss the topic and other similari ideas, please, Jump onto the SWLing forum at https://SWLing.net and open a discussion there, I’ll be more than Happy tò participate and share my ideas and experiences 🙂
A suggrstion from direct experience:
Add a BNC connector to the MLA-30+ preamplifier and replace the (bad) coach with a decenti One
Connect the preamp tò a wire loop terminated with a resistore tò offer the preamp and (almost) constant impedance and improve performance, the attenuation from the resistore Will be compensated by the preamp
Tò be more clear; see this
https://swling.net/viewtopic.php?t=172
Just replace the 9:1 used there with the MLA-30 preamp and give It a spin; if you want the loop May also be installed horizontally