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Reviews Categories | Antennas: HF Verticals and Wire | Wellbrook ALA-330 active magnetic loop antenna Help


Reviews Summary for Wellbrook ALA-330 active magnetic loop antenna
Wellbrook ALA-330 active magnetic loop antenna Reviews: 5 Average rating: 4.0/5 MSRP: $£145 or 250 euros ready to use
Description: LW/HF Active Magnetic Loop
Product is in production.
More info: http://www.wellbrook.uk.com/
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You can write your own review of the Wellbrook ALA-330 active magnetic loop antenna.

AD0BL Rating: 5/5 Sep 18, 2012 12:19 Send this review to a friend
Excellent results here  Time owned: more than 12 months
I've owned the antenna for about 2 years. Installed the antenna outdoors using the supplied connector boot, coax seal, and petroleum jelly coating on the BNC connector (per the installation instructions) and I've had no problems with the BNC connector. The antenna is much lower noise (less static) than wire antennas. My experience with this antenna has been excellent. I use it as a ham receive only antenna and a dipole to transmit and it is excellent in this role.
 
N2ZLC Rating: 3/5 Feb 21, 2011 19:43 Send this review to a friend
Temper your expectations  Time owned: more than 12 months
I compared this antenna to a J-Pole designed for 2 meters. The loop was in my shack; the J-Pole outside on the roof. The J-Pole handily trounced the loop in every way. Test stations included CRI and RTI.

I did not test this antenna outside on the roof. My point is simply to counter claims that this antenna works better indoors than other SW antennas work outdoors. NONSENSE. If a 2-meter J-Pole can beat this, imagine what a true SW antenna could do.

I agree with other reviewers who say that this is a fine indoor antenna when outdoor options don't exist. But temper your expectations.

Furthermore, the chassis is cheap plastic, easily cracked, and difficult to mount. The internals are weatherized to some degree but I wouldn't use this outdoors unless I was adventurous. As other reviewers have noted, the BNC connector is atrocious.
 
AUSSIE Rating: 5/5 Nov 6, 2010 00:48 Send this review to a friend
Excellent  Time owned: 0 to 3 months
I bought a Wellbrook-ALA330S Active Loop been testing it for the past few weeks facing different directions so far its doing an excellent job monitoring hf aero/utilities already own the 1530 radios i am using are Alinco DX-R8,Icom-R75,Palstar-R30A,Ten Tec-320D.
 
N9SLR Rating: 3/5 Jan 1, 2009 18:48 Send this review to a friend
limited by BNC  Time owned: more than 12 months
I have now owned the ALA-330 active magnetic loop antenna for over 2 years, before that having owned an RF Systems DX1 Pro. Both antennas were meant to supplement listening on my main antenna, a 90 foot B&W Twin Folded Dipole (T2FD) mounted 15 - 20 feet above street level in a suburban neighborhood. I also have a 25 foot long wire just thrown out the window and directly connected to one of my receiver's high impedance antenna posts. My receiver is an AOR 7030 plus.

I have waited this long to post a review due to mixed results I have been having related to the BNC connector on the ALA 330. This has been an issue since day one. This loop antenna requires a perfect connection on both sides (center wire and braid) of the BNC. Anything less results in the antenna losing it directionality in the LW - 3 MHz range and acting like a nondirectional short wire amplified antenna. The shortcoming does not affect listening above 3 MHz, Andy Ikin, of AOR has been extremely helpful and very responsive to emails. However, I guess we have a fundamental disagreement. He believes that the BNC type of connector is completely adequate for an outdoor installation of a rotating antenna, and my experience tells me otherwise. I am now using gold plated BNC connectors found in a Marine Electronics catalog, and although the "loop effect" lasted a couple of months (vs. a week or two with other connectors and adaptors), even with this gold connector, sealed by the AOR-supplied rubber gasket, the connection finally became less than perfect, and I again lost the "loop effect". My only solution is to take the antenna off its 10 foot mast, remount it at 5 feet so I can connect and disconnect the BNC every few weeks - ridiculous in an antenna of this cost. Potential buyers should be aware of this issue prior to mounting the antenna so that it is difficult to access.

Antenna performance is very good, especially for size. The antenna has always outperformed my 25 foot antenna on SW, and LW, but occasionally the "minibeverage effect" of even a 25 foot wire directed at a MW station can beat the loop (I listen to WCBS 880 kHz, from Wisconsin). On the other hand the T2FD virtually always beats the loop on SW, most noticeably for very weak signals, where the low noise on the T2FD permits signal detection that is lost in the noise of teh ALA-330. This is true even when the signal of the ALA-330 is higher in S-units than the T2FD. A typical example would be reception of Australian 120 m targets on 2310, 2325 and 2485 kHz during my local morning. The ALA-330 can barely pull these out of the background noise, while the T2FD clearly hears the signal above the noise.

This model, although set up for reduced LW sensitivity still greatly outperforms my other two antennas in this frequency range. However, unlike my RF Systems DX1, I have never been able to detect a European LW broadcaster with the ALA-330. Also, in the MW and LW range one should not have undue expectations as to the directionality of the loop. It is the NULL that is very sharp - and you can null out perhaps one station as you try to hear another. The null is indeed sharp - and over a range of 10 -20 degrees of rotation signals can be virutally made to disappear. Tuning to maximum signal is not an effective way to go after a target, as the peak is just too broad to effectively isolate the signal - thus the effect I note above, where a 25 foot wire outperforms this expensive loop in detecting WCBS 880 kHz at my location.

In summary, the ALA-300s is best suited for an individual in a compromised listening location - it is not a substitute for the SWL looking for performance equal to a low noise passive antenna such as the T2FD. On the other hand, it is clearly an improvement over simply hanging a wire out the window. The directionality of the loop below 3 MHz is very useful for nulling out signals, and clearly improves functionality in the MW and LW bands, but the unreliable BNC connector demands placement of the antenna where it can be easily accessed.
 
ONL5183 Rating: 4/5 Oct 1, 2002 17:32 Send this review to a friend
Useful  Time owned: 0 to 3 months
Hi,
Note that a more readable version of this reviw with some pictures is available on my webiste,
http://www.astrosurf.com/lombry/qsl-ala330.htm

Review: One day or another we all experiment radio interferences due to man made noises. Chhhhhrww … do you remember that sound ? Sometimes severe these undesired signals can easily drow out your strongest DXCC and ruin your QSO or drow out all your hope to get the QSL of your most wanted DXCC... This is not a problem if the source of QRM is intermittent or occasional. But that becomes a really problem if the QRM is permanent. If your FCC or local radio service cannot help you in solving the problem you have no other choice that moving in a quieter place or finding a way to reduce this QRM.

Then there is the problem of working on the lower bands with an antenna well cut at L/4, what means 40m long on 1.8 MHz ; not everybody can install such a passive antenna in the garden.

At last there is the problem of matching the antenna with the receiver input, in most case that means a 50 ohm impedance to get the maximum signal transfer.

So usually in some bands our installation is far to match the desire figures and to transfer all power to the receiver and vice versa.

However the main problem remains the QRM.

Currently in the appartment in which I live in LX I experiment much QRM generated by what I suspect to be a poweful source of electrical noise, but that I cannot located yet.

I can made this comparison because in another home I use a 40 m long wire tied between 3 and 5m high in the garden that captures nearly no QRM at all on any HF band. Of course the location explains that : the second one is far from urban environment, on top of hills and allows me to capture nearly all DXCC without consulting the cluster. But in my QTH in LX, also located in the country but not as quiet as the second, due to a lack of space I had to use a 15m sloper tied outdoor to a fence at the end of the garden and attached to 20m of wire that run indoors across the appartment at ceiling level. This is far to be a performing antenna system… So both installations are not exactly identical but in LX I capture too much QRM : the S-meter exceeds sometimes S-9, with an average level of S-7 ! In others words the noise is permanent. Even my computer (the keyboard control LED, the screen, the reboot/shutdown phases), the scanner, some power supplies or a digital camera recharger are also strong QRM emitters. All HF bands are concerned but mainly the one between 20-10 m, the bands I use the most for DXing in summer… So I could not continue and complete my DX awards this way.

Searching on Internet I have found several products like the MFJ noise canceler and Timewave DSP. However the first and similar product are not easy to manage and the second in an external and audio DSP not a true IF DSP, so I needed a solution more powerful and easier to use.

Then I found Wellbrook products and its active magnetic loops, that, according the manufacturer were especially designed to remove all QRM generated by electrical sources.
Was that my miracle solution ? At first sight I had a mitigated feeling about performances of such small antennas. But after have read many articles about the subject and being not an expert either in antenna nor in electronic, I accepted the challenge and for my SWL activities I bought on the suggestion of Andy Ikin, their salesman, the ALA-330, an active magnetic loop antenna dedicated for listenings purposes only (there is also and emission version the ALA-1530)

What is a magnetic loop antenna ?
In a few words the ALA 330 is a compact HF antenna constituted of an aluminium sheated loop of 1.1m of diameter. It is especially designed to reduce sensitivity at LF and MW to prevent the receiver overload from multiples high power AM broadcast in city areas. Complementary its design permit to reduce QRM.

The secret of this kind of antenna is to capture only the magnetic component of the electromagnetic field. An ordinary antenna, a passive element like a longwire or even a beam, works by capturing the electric field of waves and transmit it to the receiver. However a magnetic loop does not work with this component of the electromagnetic field.

When we know that most devices are electrically powered and can generate severe QRM in all HF bands, the active magnetic loop looks like a miracle solution as it is nearly insensible to electrical sources. It is able to reject most locally radiated noises, like mains wiring, air-conditioner, power supply, fluorescent lamps, dimmer, so much sources of man made noises in HF bands and higher frequencies. For sure the QRM is not completely attenuated but you can expect a reduction that can exceed 4 points on your S-meter !

Then there is the intermodulation. When your receiver gargoyles of thousands noises, the fact of inserting an attenuator (button ATT on my TS-570D) can occasionally suppress these noises and stations until then flooded in the QRM become audible.

Technically your first stage is saturated by two or more stations and the system created products of intermodulation, in other words signals do no more exist; in fact they are multiplied among themselves and fall outside your band. These mixing of frequencies are called intermodulation products of the third order. The intercept point is the level at which the range (amplitude) of intermodulation signals equalize the desired signals; this point is the famous IP3. Between the compression point and the minimum detectable signal level (MDS) we are in the working zone of the amplifier or of your receiver, that represents the blocking dynamic range.

With this loop the dynamic of the second and third order intercept points are typically +70 dBm (IP2) and +40 dBm (IP3) respectively. So with such a loop the level of intermodulation products are well below the QRN and QRM level what is not necessary the case with the ALA-1530 which is more sensible to this effect.

Still more interesting, compared to a whip antenna, the loop improves the S/N up to 20 dB and is able to ensure a very low level of intermodulation in strong signals environments. Due to the interference rejection in vertical position this receiving loop displays a classical dipole Figure-of-Eight directivity pattern that are enhanced by deep nulls.

The magnetic loop displays also a very wide frequency response requiring no antenna tuning. The ALA 330 display a relatively flat response in the frequency ranging from 5 to 30 MHz and matches directly to the receiver without having to adjust the impedance. The impedance machting in not required - it is even forbidden with a receive antenna (see below) - due to the fact that the current induced into the loop is proportional to the field strength rather than to the frequency. According the manufacturer and from my experience, the useable reception range practically extends from 150 kHz to over 100 MHz.

At last a magnetic loop is a compact antenna that requires only 1 meter square in your shack (or outdoor for "all weather" models), practically nothing compared to the required space for any other model of antenna (long wire,dipole or beam). Better, this loop must not necessary to be placed in front of your window or near the balcony. I first placed mine near the window as displayed below but I observed that the reception on the lower bands (40 to 160m) was still improved when I placed it ... at ground level, behind a door near a wall located 3m away from the window !

However according the manufacturer even if the loop can be used indoors and at ground level it performs best if you place it 7 m high and away from noises radiated by buildings.

All these advantages made of this kind of antenna the ideal model for people with limited space, interesting in LW and HF listening and experimenting much QRM.

Installation and first activation

The product was originally packaged and I suspect the postman to wonder what could hide this huge « hula hop ». Imagine how to transport a 1m-loop by messager : all the loop was envelopped in a thick and dense tube of foam, maintained internally with 2 bamboo sticks ! It arrived some weeks later at home in Luxembourg in excellent state without additionnal charges. Great !

Once the antenna unpacked and seeing no "assembly manual" excepting a small graphic drawed on a technical sheet (the same as the one published on Wellbrook website), I had a few seconds of stress. How could I assembly all that stuff ? The kit contained 1 metallic adapter and three screws to fix the base on an optional mast or tripod, the antenna interface, in fact a small plastic box that I opened to discover it was flooded with "black gelatin", so a true black box working as amplifier on which it was written "antenna" on one side and "receiver" on the other side from which run a small coax RG58C ended with a PL-259 connector. Good, I already recognized the jack to connect to my RTX antenna terminal. The interface had also to be connected to an external power supply for which only the jack was supplied. Although this material looks fine and use quality components this is however a kit for amateur : BNC and RG58C coax are not known to be the best components we can find in a ham shack… On another side these components are know to be more widely used by RF professionals then other types for receiving applications ! Anyway, if all that works I will already be happy.

As I wondered why the manufacturers did'nt include better components, M.Andy Ikin explained me than he didn't see any reason to use RG213 and UHF (PL) connectors : "the attenuation difference, he said, is less that 1 dB per 30 m. Also the pressure sleeve BNCs offers good protection against moisture ingress into the feeder".

The so-called "manual" explaining how to assembly the antenna was minimalist, and from what I seen the technical sheet was "compatible" with all magnetic loops sold by Wellbrook, including the outdoor and emission models (ALA 1530, etc). So I took the risk to "adapt" the graphic to my ALA 330 model, assemblying all parts according what I see on this unconventional and unappropriated user manual.

As expected I encounted my first problem : there were neither connectors antenna side, nor power supply, what is a pity for what these components cost (21 euros vs the 140 euros that cost the antenna). So I wondered why the manufacturer didn’t include these parts in the kit. M.Ikin to answer, "to date, I have not been able to purchase in the UK a 12 volt 200mA Linear regulated power supply with a 230Volt European plug. I don't provide the coax cable or BNC Connectors because each user has different cabling requirements". But I suspected there was a more pragmatic reason that M.Ikin explained me "Also, the additional weight of the BNCs and feeder cable would double shipping cost and make the antenna less competitive to other active antennas (Dressler and RF Systems for example )".

So in the next hour I had to buy the required accessories : 2 male BNC connectors, 8m of RG58C 50 ohm coaxial to feed it and a stabilized power supply 220/12V 400mA or higher with several extractible jacks to the nearest electronic shop. Hopefully the antenna interface came with a fuse (315 mA) and as I told with a short coax ended with a PL-259 connector I immediately connected to my RTX antenna input terminal, beside my longwire terminal that was always connected to compare signals received by both antennas.

After have made some mistakes in assembly parts (inversion of the power supply +12/-12V on the interface, short-circuited the coaxial, blow up the fuse), some hours later I posed the loop on front of the window, 1m high, street side.

With its 1m of diameter the loop is rather cumbersome but as it is very light - it is made of aluminium - it was easy to place behind the veils or anywhere else, the manufacturer suggesting to place it at ground level. I switched on my Kenwood TS-570D anywhere in the bands where I could capture an emission. I also remembered the warning of the manufacturer : never use the ALA 330 in emission or I should experiment some hardware damage. But I didn’t understand why I couldn’t use it in emission until I questioned an OM : in fact the small transistors located in the interface will not support the 100 W emitted by the TX and will explode the system. OK, sworn, I will never use it for emission !

Once the loop placed near the window I did various tests : I changed its position in the living room, I posed it on the ground, more or less near or far from the concrete walls and I changed its orientation related to the signals. I used it at night (23z) and in the middle of the day (11z), in the morning (06z) and in the evening (18z), thus in nearly in all my working conditions, under all kinds of QRM and even during bad weather (foggy, wet or rainy).

After some weeks of practice what can I conclude ? Even if using the loop indoors is not a valid comparison with an outdoor longwire, the results are quite impressive, and still more knowing that this loop is also marketed as an alternative to the active whip antenna ! But see by yourself.

Results in the field
In one word I can say this active magnetic loop is "more useful" than my longwire flooded in QRM. I prefer to not say "very useful" for several reasons explained below. However my appreciation is very positive in regards of its performances in respect with the space it requires.

Without having the possibility to test the magnetic loop with a spectrum analyser I can only test the audio performance of the antenna on stations or beacons I heard on bands.

First the SWR. Wellbrook states the ALA 330 has no SWR. In fact all active antennas don't quote SWR curves because the SWR is dependant on the source impedance of the receiver. i.e. the output of an active antenna is broadband amplifier driving the feeder. Therefore the impedance matching is not required. It is even forbidden to activate the antenna tuner as it will send about 10W in the antenna and there is a chance that this power damages the transistors of the interface. Practically the interface transistors will support this low current as the tones are sent in CW but I prefer to tell you to avoid such practice.

The antenna position and location. As I have bought the magnetic loop exclusively for indoors usage, I move the loop in various places in the living room, near or far from the walls (made of bricks) or from the windows located street side. When I placed the loop on the ground, under the window, in front of the radiator turned off, the QRM increased a bit (1 point) and disappeared when I placed the loop back just in front of the window, 1m high and behind the veils. The QRM reduced a bit more when I placed the loop at ground level, 3m away from the window, near a supporting wall. So I definitively placed it at that location, behind a door. This is strange but it is in that position that I capture best all stations with the less QRM.

The fact to change the loop orientation from vertical to horizontal, to turn the loop of 90° or to tilt it at 45° didn't change the signals or the QRM intensity, at least in my location. However the fact of changing its orientation in regards with NSEW positions changed sometimes the reception of noisy signals or the reception of AM broadcasts in the lower bands (QRM RS 59+ to 55+ in best cases, about AM signal the loop lost up to 2 S-point but often no change.

So I can already conclude that this ALA 330 is not very sensitive to its position vs the signals but well to the distance to concrete or maybe to dense objects containing metal.

I also made a test installing the loop in the cellar, what means in a room under ground level made of concrete all parts, which walls are not more tick than the one of the appartment. Amazingly, I continued to listen stations with nearly the same intensity as at the second floor. I am not sure however you could get the same result in a building which walls are made of a mix of concrete and a mesh of metallic wires.

At last the stations signals. In the HF bands signals are globally stronger with less QRM using the loop than vs my longwire sloper, mainly in bands from 17 to 10 m, with the best noise reduction in the 17m and 12m bands where the QRM dropped from S-9 to as small as S-1 ! For the first time for many weeks I can hear in LX stations that were flooded previously in the QRM.

As strange as unexpected on the 20, 40 and 80m band, the loop captures the same (on 20 m) and sometimes signals less strong than my longwire. I cannot explain this phenomenon. In the best conditions the S-meter of stations increases a bit but usually it stays at the a same level of intensity or drops of one or several points using the magnetic loop. However even when signals display a lower intensity on the S-meter, the QRM is reduced. In a few rare occasions the QRM increased when I use the loop. In such cases I moving the loop I can improve the reception and still reduce the QRM.

In the 160m band, where the loop is theoretically not adapted, the QRM is also much reduced with the loop, dropping i.e from 59+10 to S3 but this band was free of OM at the time of my tests and I checked the signals intensity with beacons.

Below 3 MHz, switching to AM mode the few broadcasts I have listened with the loop are audible but their signals are similar or even dropped of 3 S-points compared to the signals that I received with the longwire. This observation requests however some comments. In this range of frequencies it is a fact that the signal usually drops of several point, what means the received power is reduced over 4 times... up to extinct ! The last example is particulary amazing at 1145 kHz (VOA captured at 11z, theoretically on 1143 kHz) and the antenna tuned with the tuner : the longwire receives its signal over 59 while the loop oriented in the E-W plan does not capture the least signal. However the situation is not desperated : when I rotate the loop plan of 45° and place it in a NW-SE position, the signals come back and are well amplified and audible. In practice this position is also favorable to HF listenings but it is not really practical in my appartement as the loop is then right in the middle of the passage !

I discussed with the manufacturer as I wondered that the loop displayed on some frequencies a lower gain than my longwire. Andy Ikin explained me that "it was necessary to prevent antenna overloading and intermodulation. Generally the lower noise performance of the loop outweighs the higher signals and QRN from Longwires and active Whips. The low gain of the ALA 330 below 3 MHz prevents close Megawatt AM broadcast from overloading the antenna and the RX. This is a plus feature for some users". I cannot contest this fact.

About peripherals, like dimmers, battery rechargers or computers used nearby the RTX, the loop is much less sensible to the RFI they could generate than the longwire. In short, although the loop captures also their interferences, their intensity displays a level much lower than using the longwire (2 points or more). In others words now I am no more afraid to use my computer and periphals when my RTX is switched on; this is an excellent news !

Figures.
As I cannot display numbers in columns here, please refer to my webpage on http://www.astrosurf.com/lombry/qsl-ala330-2.htm

In summary using the loop the QRM in reduced from none or 1 S-point (4 times) to over 6 S-points (RS of QRM 57 to 51, 59+10 to 55), allowing weak signals to rise above the QRM.

By way of conclusion
Plus of ALA 330 :
- Reduces drastically QRM over 7 points in 17m to 10m bands, much less useful in the lower bands at night
- Requests no antenna tuner for matching impedances (and forbidden with ALA 330)
- Very light antenna, not combersome compared to any passive antenna
- Quality of assembly kit
- Easy to assembly and installed indoor in a few minuts
- Not too expensive in regards of its performances
- Suited for LW and HF listenings
- Highly recommended when space is limited
- Good support from the manufacturer

Minus of ALA 330 :
- Add 1 more point of QRM in the 80 m band, no improvement in 20 m
- Reduce at bit the signal intensity in the 30-40m bands in HF and below 15 MHz in AM.
- Should be rotate in its plan to increase signals and reduce QRM
- User manual unappropriated, lack of technical advices (on paper of on website) for the beginner
- For a novice user, basic accessories missing (BNC, power supply) with risk of errors when assembly the parts.

Should I place another order if needed ? Surely. But I should probably buy a more sensitive model if available. But more important I should change all cabling system and connectors with « ham approved » parts : BNC with PL connectors (or an adaptor BNC/PL) and the RG58C coax with a RG213U 50 ohms coax, in order to reduce the signals attenuation, losses in the cable and still a bit more QRM in order to improve the reception.

For more information
The ALA 330 as well as other loop antennas suited for emission can be obtained from Wellbrook Communications, Wellbrook House, Brookside Road, Bransgore, Christchurch, Dorset, BH23 8NA, U.K.

The antenna stand alone costs £144.95 or 231.42 euros charges included for Europe. Completed with all requested accessories (power supply, BNC and wire) it cost me about 250 euros.

Hope this help and be a useful contribution on a subject too rarely tackled.

NB. Thanks to this review, some licensed OM told me they decided to buy the emitting version of this antenna, the ALA-1530.

73
Thierry, ONL5183
http://www.astrosurf.com/lombry/menu-qsl.htm
 


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