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Paul Walker’s battery-powered Wellbrook antenna in remote Alaska.
Many thanks to SWLing Post contributor, Pete Jernakoff, who writes:
[…]I’m hopeful that one of your readers might be able to suggest a solution to my problem.
I have an older Wellbrook Communications active loop antenna that is powered by a 12 v AC-to-DC, center pin negative, plug-in power supply (Stancor AC Adapter, was supplied with the antenna).
I’d like to power the antenna from a rechargeable battery in order to make the antenna portable and to eliminate any noise that might be emanating from said power supply (which, as an aside, runs very warm when in operation).
My problem is that I cannot find any rechargeable batteries (lithium ion preferred) with a center pin negative output. All of the ones that I can find online have center pin positive outputs (such as the TalentCell 12V/6000mAh rechargeable battery that I’ve purchased to power my other, more recently produced, Wellbrook Communications active loop antenna whose amp needs a center pin *positive* input).
Thanks in advance for consideration of my request. Btw, love your blog! I’ve been an avid reader of it for quite some time now.
Post readers: If you have any suggestions for Pete, please comment with any relevant links to help him make the purchase. I’m guessing Pete isn’t interested in re-soldering a coaxial plug for negative tip polarity at this point.
By the way, I used a photo of Paul Walker’s Wellbrook at the top of this post because I recall that when he lived in Alaska, he powered his Wellbrook loop with a rechargeable pack (and during the winter, I also recall he struggled to keep it warm enough to provide power for any length of time!). Perhaps Paul can comment.
Wellbrook Mag Loop antenna at Mark Fahey’s QTH near Sydney, Australia.
Many thanks to SWLing Post contributor, David Goren, who writes:
I need a new power supply for one of my Wellbrook loop antennas.
Do you know of good source for reliable ones? I forgot where I obtained the last replacement which worked fine until the wire attaching to the plug worked loose.
Here are the specs:
Plug in Class 2 Transformer
Model: DC1200300R
Input: 120VAC 60 Hz 9W
Output: 12V DC 300mA
manufacturer: Sandin Ltd.
Searching online delivers a mixed bag of somebody’s old power supply.
Post Readers: Any suggestions for David? I’m sure he’s particularly interested in a good quality power supply–one that’s quiet and would last a few years. Please comment and include links when possible!
Many thanks to SWLing Post contributor, Mike Ladd, who shares the following video by Rick King who compares four mag loop antennas: the MLA-30, Cross Country Wireless, Bonito ML200, and the Wellbrook 1530LN.
Although we’ve previously posted reviews and comments about the MLA30, I’m quite impressed that it gave the venerable Wellbrook a run for its money. I’m not surprised the Bonito ML200 was the winner here–Bonito quality is second to none.
I live here in South Florida and am unable to erect anything outdoors. I do get pretty good reception on my Grundig Satellit 800 and Tecsun PL-880. For these, I use either an indoor slinky antenna I bought on E-Bay; or an active indoor tunable loop antenna. This is one of the models past reviewed by you. It is Australian made, and covers 6-18 MHz. Please comment if you can on antenna usage.
Thank You very much!
First of all, I’m glad you enjoy the SWLing Post, Tim!
Great question: no doubt you understand that the antenna is the most important part of your radio equation!
You’re on the right track with a PK Loop if you live in an apartment and have no way of putting an antenna outdoors. Being a small magnetic loop antenna, the PK Loop should help mitigate a bit of the noise in your apartment building.
What I love about the PK Loop is it’s small enough that you can re-position and rotate it to tweak noise rejection and find the quietest spot in your listening room. When I travel by car and even by air, the PK Loop is a welcome companion.
Before we talk about investing in a better indoor antenna, let’s make sure we cover a more affordable option first…
External wire antennas
If you have operable windows in your apartment, even fishing a thin-gauged wire out of your window–allowing it to simply hang along the outside of the building–could improve your reception significantly. Of course, if there’s a source of noise outside of your apartment it might only make things worse, but this is at least an inexpensive experiment and the results might impress you.
I had a fantastic opportunity to evaluate how well the PK Loop would perform in a typical hotel room. My buddies Eric (WD8RIF), Miles (KD8KNC) and I stayed overnight in a hotel on Wright-Patterson Air Force Base during our mini National Parks On The Air DXpedition.
The hotel room was indeed dense with RFI.
We hooked my Electraft KX2 to both the PK Loop and to a simple random wire antenna.
Without a doubt, the PK Loop was much better at mitigating radio noise than the wire antenna we hung on the inside of the hotel window.
Unlike most modern hotels, however, this one actually had operable windows, so we tossed the random wire out the window and made another comparison. In this case, the external wire antenna consistently outperformed the PK Loop, no doubt because it had the advantage of being outside the radio noise cloud within the hotel’s walls. It goes to show that outdoor antennas–even if simply hanging from a room window–will almost always outperform comparable indoor antennas.
So, if you have a way to dangle a wire out one of your window, give this a try.
How long should the wire be? I suppose it depends on how much vertical space you have below your window. For starters, I’d try to suspend at least eight feet of wire outside. If I had the vertical space, I’d try as much as 31 feet.
Important: First you must check to make sure your wire couldn’t possibly touch electrical lines. Never lower a wire outdoors if the wind could blow it into an electric service entry point, power line or any other type of line or cable. You should do a thorough inspection of the site first.
With that said, keep in mind: Stealth is key!
Can you spot the wire antenna in this photo? Of course not.
Use a thin wire with a black or dark jacket/insulation. Only lower it when using it–don’t leave it out all day long. Check to make sure your antenna isn’t going to interfere with your neighbors below (like landing in their outdoor grill or flower pots!). One strong complaint from neighbors could shut down your operation permanently.
Now back to loops…
If you don’t have operable windows or a way to deploy a wire antenna outside–or you’ve tried a wire antenna and results were unsatisfactory–then you will be forced to stick with indoor antennas which almost always leads you down the path of larger amplified wideband magnetic loop antennas.
This is a topic I covered extensively earlier this year.
I’m plotting to write a more in-depth article about antennas in the coming months, but it will focus on external antennas and methods of mounting them. When you have no means of mounting an antenna outdoors, in my opinion, your best options are the ones mentioned above.
Post readers: Have I overlooked an indoor antenna option? Please comment if you have experience with indoor antennas!
Many thanks to SWLing Post contributor, Chris Freitas, who writes:
“I am thinking of the new RSP1A SDR. Would you know of a good indoor antenna that would work well with it?”
Your antenna question is simple, but the answer is complex!
First off, I think the RSP1A is a great choice as it’ll give you proper exposure to the world of SDR (1 kHz to 2 GHz!) at a modest price.
Unlike a portable radio of course, your SDR must be connected to a PC, laptop, tablet or some sort of mini computer like Raspberry Pi. This limits your ability to easily try different antenna locations within your home compared to, say, a battery-powered portable radio. It might take some dedicated experimentation and patience.
Indoor antennas are so vulnerable to the radio noise within your home.
If you live in an off-grid cabin with no radio interference nearby, even a simple $1 random wire antenna hooked up to RSP1A’s SMA connector would yield results. I occasionally spend my summers in an off-grid cabin and it’s simply amazing what you can do with a modest setup when there are no man-made radio noises around.
Listening to the final broadcast of Radio Netherlands in an off-grid cabin on Prince Edward Island in 2012.
But how many radio enthusiasts live in an off-grid cabin? Answer: very, very few! Most of us only get to experience off-grid life during natural disasters when the electrical grid has been damaged in our neighborhoods.
The reality of indoor antennas
You’ve told me previously that you live in an apartment in an urban setting, hence you probably cope with a lot of RFI.
When an antenna is indoors, it is forced to function within this RFI-dense environment. Your telescoping whip or wire antenna doesn’t discern between radio noise and your target broadcast signal. Thus, noise can overwhelm your receiver, essentially deafening it to all but the strongest shortwave broadcasters.
This is why if you had a means to put a small random wire antenna outside–even if it was simply draped outside a window–it would likely perform better than an indoor antenna. I’m guessing this isn’t an option for you, Chris.
Think loops
A broadband loop antenna (image courtesy of wellbrook.uk.com)
While you can build an amplified mag loop antenna (like our buddy, TomL) it’s not a simple project. Passive single turn loop antennas, on the other hand, are quite easy to build but are narrow in bandwidth (here’s a very cheap, simple passive loop project). You would likely design a single passive loop to serve you on a specific brodcast band and would have to retune it as you make frequency changes. You could build a passive loop antenna for less than ten dollars if you can find a good variable capacitor. Here’s another tutorial.
Commercially produced amplified wideband magnetic loop antennas are not cheap, but they are effective. If you’re a serious SWL, a good mag loop antenna is worth the investment.
Here are a few of my favorites starting with the most portable:
PK Loops are not as broad in bandwidth as the other antennas I mention below. You will have to retune the loop with any band changes and sometimes even within a specific meter band.
W6LVP sells two versions of the antenna–since you’re not operating a transmitter, this $250 model would be all you need. indeed, if I were in your shoes, this would likely be the loop I purchase–very cost effective.
Wellbrook Loops
Wellbrook antennas are the staple magnetic loop antenna for many DXers.
Wellbrook makes a number of loops, but since you have no plans to mount this outside, I believe their indoor model would suffice.
Other loop options
There’s no shortage of magnetic loop antennas on the market, but most are pricer than the models I mention above and I know you have a tight budget. Here’s are some models we’ve mentioned on the SWLing Post in the past:
I hope this helps, Chris! This post is by no means comprehensive, so I hope others will chime in and comment with their experiences. Good luck fighting urban noise and I hope you enjoy your journey into the world of the SDR!
One fits in a car (well, most vehicles anyway) and another easily slides into a small daypack; which antenna is best for DXing on-the-go? The ALA1530LNP and Boni Whip are at opposite ends of the portability scale (as well as the price scale).
I’ve written about the ALA1530LNP in the pages of the SWLing Post before, where I compared it against another Wellbrook loop antenna on extremely weak medium wave signals. The ALA1530LNP currently costs $413 USD including shipping to the Seattle USA area where I live.
More recently I’ve been intrigued by UK Oxford Shortwave Log’s (YouTube) excellent videos demonstrating the DXing prowess of the very compact, highly portable Bonito Boni Whip antenna. Through a Bonito USA dealer I was able to purchase the Boni Whip at an attractive $99 USD price (plus $11 shipping).
So, is it fair to compare “apples and oranges”? Maybe not, but it was fun and interesting nonetheless to take both antennas to the countryside to find out how they perform head-to-head in a portable situation. My destination was a small forested campground, in a valley east of this beautiful Mount Rainier, Washington scene:
In mid-July, Tipsoo Lake near Mt. Rainier is still surrounded by snow.
Over the course of three days I compared the two antennas with these receivers:
Eton E1XM
Sangean ATS-909X
Elad FDM-S2
I set up the E1XM and ATS-909X receivers on a portable tote box with the antennas powered by SLA gel cell batteries and using a two-way antenna switch for instant comparisons.
Each antenna was mounted on its own “pro” speaker stand and separated 60 feet from each other. The antennas were connected to receivers by equal 100 foot lengths of RG-58 coax cable, and were over 80 feet away from my laptop computer (the only noise source in the area).
In keeping with the uber-portable theme of the Bonito antenna, I used a very compact 1.2Ah SLA gel cell battery for its power injector (junction box). Since the antenna consumes a mere 45 ma. of current, this small rechargeable battery will power the Boni Whip for many, many hours.
The Wellbrook ALA1530LNP requires a still reasonable 200 ma., and I brought along a much larger battery to power it.
Below are a selection of 30-second medium wave and shortwave recordings, each one of them beginning with the Boni Whip and switching to the ALA1530LNP midway through the recording.
Boni Whip vs ALA1530LNP – E1XM Receiver
660 kHz
870 kHz
1660 kHz
3330 kHz, CHU Canada
4960 kHz, VOA Sao Tome
9535 kHz, R. Algerienne
11600 kHz, Denge Kurdistan
11760 kHz, R. Havana Cuba
EDIT 7/14/2017: 11905 kHz, Reach Beyond Radio, Kununurra WA Australia (tentative; listen for the Aussie-accented weather forecast at the end of the Wellbrook loop portion. This catch was at 03:48 UTC, which matches up with the brief English language broadcast in Reach Beyond’s schedule for 11905 kHz. This catch does not appear to be China National Radio as I first thought.)
Boni Whip vs ALA1530LNP – Elad FDM-S2
These 30-second videos are from the Elad SDR’s FDM-SW2 software. As above, the first half of each recording is the Bonito antenna followed by the Wellbrook loop. If you maximize the playback of a video to full screen you can read the signal-to-noise ratio (SNR) change (“Delta”) as the antenna is switched to the ALA1530LNP.
The compact Boni Whip is a unique commercial design of “mini whip” antenna, pioneered by Roelof Bakker, PA0RDT some years ago. As with all these compact e-field antennas they can be a significant “noise sponge”, collecting any RFI or interference in the area. This is especially true if the coax shield is not grounded. Despite using twoBryant/Bowers design of RF chokes in series, the Boni Whip’s reception was degraded by RFI emitted from my laptop over 80 feet from the antennas. The RFI was quite a bit worse without any RF chokes in-line. You’ll note though that even the Wellbrook loop received some interference from the laptop on the higher shortwave frequencies.
Observations. On medium wave (E1XM examples) the directionality of the Wellbrook loop could be noted on one, maybe two of the three recordings. This can be a benefit–or not–depending on your goal. (I did not rotate the Wellbrook loop to null or peak any specific MW signals.) The omni-directional Boni Whip would not be the antenna of choice for a hard-core medium wave DXer; however, it is extremely compact and lightweight for camping and travel if you will be DXing or SWLing on shortwave also. The Wellbrook though is highly regarded as a medium wave DX antenna, especially when used with a rotor to take advantage of its sharp broadside nulls.
I didn’t test the Boni Whip on long wave, but Oxford Shortwave Log and others report it does very well on LF. I tried the antenna on FM frequencies against the Eton and Sangean’s telescopic whip antennas but in every case the reception was worse on the Boni Whip.
As I expected on shortwave, the ALA1530LNP greatly outperformed the Boni Whip on some signals. On others, reception was extremely comparable! The 3330 kHz CHU recording surprised me with the neck-and-neck reception. At this tropical band frequency there may have been some directionality to the signal, and the loop may not have been oriented optimally. The 4960 VOA reception was also very close.
I was disappointed, but not surprised at the RFI pickup of the Boni Whip when using my laptop and the Elad SDR receiver. The two RF chokes tamed the spikes and hash a bit, but removal was far from complete. The Wellbrook wasn’t always “clean” in this regard though.
Final notes. I think the Boni Whip is an extremely high value in a “jack of all trades” very portable antenna. Like Oxford Shortwave Log and others, I find this active antenna’s noise level to be extremely low, helping its sensitivity reveal weak DX signals in a surprising fashion. I would not hesitate to use this antenna away from noise sources when traveling with a non-computerized receiver. Well done, Bonito!
Is the Wellbrook ALA1530LNP worth four times the Boni Whip’s USA price? To the serious DXer who has no room for large passive antennas (Beverages, phased delta loops, DKAZ, etc.), the 1-meter diameter Wellbrook is clearly in a class of its own. By the way, the US Dollar to UK Pound ratio has improved in recent months, so the Wellbrook is an improved value for USA radio hobbyists now.
Truly this was an “apples to oranges” comparison, but I thoroughly enjoyed using both models. I welcome your comments, particularly if you also own both of these fine antennas.
Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington. He’s a regular contributor to the SWLing Post.
Hi there, if you’re a subscriber to the Oxford Shortwave Log YouTube channel, you will be aware that I have been using a Wellbrook ALA1530 H field antenna, for 15 months or so, with (at times) excellent results. A while back I was on the lookout for a second antenna, however at more than £250, I couldn’t justify purchasing a second Wellbrook. Ultimately I splashed out on the Bonito Boni whip E-field wideband active antenna (20 kHz to 300 MHz) and with a very compact form-factor suitable for DXpeditions/portable operation in general, the Boni whip definitely ticked all the boxes. Furthermore, with reasonable second and third order intercept points of +55 and +32.5 dBm respectively, the Boni whip, on paper at least, looked like a pretty good buy at around £100.
Initial testing at home confirmed, perhaps not surprisingly that the Boni whip could not match the SNR provided by the Wellbrook ALA1530 in a noisy, urban environment. However, less predictably, the Boni whip has proven to be a truly excellent antenna away from the ubiquitous blanket of ‘electrosmog’ at my QTH. Furthermore, it really is so compact, I simply leave it in the car in a small flight case, with a portable and connectors etc. for ad-hoc listening sessions. Since returning from my most recent trip to Brazil, I have had a chance to review my most recent catches with the Boni whip, some of which are realy pleasing and most definitely underline the excellent performance of this diminutive antenna. In particular, signals from Radio RB2 on 11935 kHz and Radio Aparecida on 11855 kHz, both low power Brazilian stations, are testament to how sensitive the Boni whip is in an electrically quiet environment. Check out also the quality of longwave signals from Poland and the Czech Republic – simply amazing for such a physically short antenna. Finally, there’s a personal first from Lusaka, Zambia, Voice of Hope Africa on 13680 kHz. All the more rewarding that this was actually copied in my work office!
I hope you found this article interesting. There are embedded reception videos below and text links for all, which will take you directly to the relevant video on the Oxford Shortwave Log YouTube channel. Thank you for reading/watching/listening and I wish you all excellent DX!
Clint Gouveia is the author of this post and a regular contributor to the SWLing Post. Clint actively publishes videos of his shortwave radio excursions on his YouTube channel: Oxford Shortwave Log. Clint is based in Oxfordshire, England.
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