Tag Archives: PK Loop C-LOOP-HDSW6-18

Indoor shortwave antenna options to pair with a new SDR

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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.

And simple, inexpensive portable amplified shortwave antennas? I’ve expressed my opinions about them before. They amplify the RFI as effectively as they do 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)

Magnetic loop antennas are a popular topic here on the SWLing Post for a reason: they’re one of the best frontline tools for fighting urban noise. (Here’s a great tutorial/presentation [PDF] describing how mag loop antennas work.)

The compact Bonito Mega Loop FX

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

The PK Loop

The most affordable and portable mag loop antenna I own is the PK Loop.  I have the more compact PK Loop C-LOOP-HDSW6-18 (6 – 8 MHz), but Guy Atkins also touts the slightly larger Ham Loop which he finds tunes beyond the advertised 3.5 – 14.5 MHz range.

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.

Click here to check out PK Loop offerings on eBay.

W6LVP Loops

The W6LVP Loop Antenna

To my knowledge, the W6LVP is one of the most affordable larger diameter amplified wideband mag loop antennas. We’ve published positive reviews of this antenna in the past.

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 loops are manufactured in the UK and have been on the market for a very long time. Their re-engineered Active Inoor Loop Antenna LA5030 would serve you well. At £240.00 (roughly $330 US) plus shipping, it’s one of the most affordable in the Wellbrook line, but over a $250 budget.

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 have the RF Pro-1B and am very impressed, but it’s overkiil for your application (and twice the price of the W6LVP loop).

Fighting urban noise

Even if you build or purchase a magnetic loop antenna, you still need to eliminate as much RFI as you can on your own.

A couple years ago, our friend London Shortwave wrote a brilliant guest post about fighting urban noise. Read through his piece and try to implement as much of his advice as you can.

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!

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A follow-up review of the PK Loop C-LOOP-HDSW6-18 antenna

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In 2016, I purchased portable shortwave magnetic loop antenna designed and built by Paul Karlstrand in Australia. I posted a “preliminary” review of this antenna in 2016 and since then have taken this loop on many travels.

SWling Post contributor, Ron, recently noted that Jay Allen reviewed one of Paul’s inductively-coupled mediumwave magnetic loop antennas. Jay gave it good marks on performance as it compares favorably with the Grundig AN-200, Select-A-Tenna M, and Terk Advantage AM–even having a performance edge due to it’s larger loop diameter. (Note that Paul makes a number of loop sizes–click here to download PDF of catalog.)

In Canada last summer, I used the PK Loop on a number of field radio listening sessions.

But what really sets the PK Loop apart from its competitors is its durability. PK’s Loops are built to be incredibly rugged. I routinely throw my PK Loop antenna in bags/packs and–unlike most of my other radio components–never worry about how it’s padded or protected. There’s little to damage unless you’re intentionally abusive to this antenna. My Grundig AN-200 antenna, on the other extreme, has exposed coated wires around its loop that I’m constantly concerned about harming in transit.

Following up…

Ron’s message reminded me that I never followed up after posting a preliminary review of the PK Loop C-LOOP-HDSW6-18 in 2016.

Shortly after publishing the review, 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.

My Elecraft KX2 connected to an external random wire antenna.

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.

A late evening listening session on the condo balcony.

Last summer, I also spent two months in a condo near Québec City. The condo was dense with RFI–the PK Loop made the experience much more bearable.  The loop couldn’t completely eliminate all of the persistent wideband noise, of course, but it did reduce noise to a level that I could enjoy some of my favorites like RRI, VOG, VOT, REE, WRMI, RNZI and even weaker stations in North America like the BBC and DW.

Even the shortwave version of the PK Loop can null out QRM to some degree by rotating the loop perpendicular to noise. I became quite adept at this by the end of our stay.

Summary

Since I purchased the PK Loop, it’s been a constant travel companion and I highly recommend it. I don’t believe you’ll find a more durable or effective portable mag loop antenna on the market.

PK Loops are built by Paul Karlstrand in Australia who has a stellar reputation with his customers. For those of us living outside Australia, there will be additional shipping costs, but they’re negligible and Paul has been exporting these loops for many, many years. I believe I received my loop within a couple of weeks of ordering it.

Click here to view a PDF catalog of Paul’s loops and products.

As an added convenience, Paul also has an eBay store where he sells the following antennas:

This year, I plan to purchase PK’s largest mediumwave loop, the model HDXLTAM that boasts a 20″ diameter. Please comment if you have experience with this loop or any of Paul’s loops!

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SWLing on the coast with the Elecraft KX2 and PK Loop

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Since I purchased the Elecraft KX2 last year, I find I do almost as much SWLing with it as I do ham radio activity. The KX2 is actually a brilliant shortwave broadcast receiver–check out these audio samples. It’s incredibly sensitive, selective and outperforms all of my portables. It’s also a joy to operate, once you learn your way around the controls.

I’ve been at the South Carolina coast all week on an active family vacation. What little time I’ve had to play radio, I’ve used the KX2/PK Loop combo.

The KX2 pairs well with the PK Loop (C-LOOP-HDSW6-18) antenna and both can easily fit in one small pack. The combo limits me to the shortwave bands, but that’s okay since I always carry an Ultralight DX receiver like the Tecsun PL-310ET, Sony SRF-39FP or CC Skywave should I decide to hit the mediumwaves.

I can set up the KX2 and PK Loop on a small table or foot stool with room to spare. I typically use a pair of headphones with the KX2 since its built-in speaker leaves much to be desired (but is better than the KX3’s internal speaker, in my opinion). With headphones, you can also take advantage of the “delay” audio effect which makes broadcasts sound much wider that the 5 kHz maximum bandwidth.

Another favorite travel receiver is the CommRadio CR-1a. Like the KX2, it’s compact, has a built-in battery and (unlike the KX2) can even be charged from a standard USB source.

I still manage to take the KX2 on travels more often than the CR-1a simply because I always have the option to put on my ham radio hat and do field/portable operation should I choose.

But CommRadio is cooking up a new radio: I’m watching the new CommRadio CTX-10 with interest since it might also serve both of these radio purposes!

The CommRadio CTX-10 QRP transceiver

I will review the CTX-10 when it’s on the market.

On a side note: since I own both the KX2 and KX3, I’m planning to purchase the KXPA100 100 watt amplifier for the shack next year. At $749 for the ATU-less kit version, it’s a hefty sum–indeed–enough to purchase another 100 watt transceiver like the Icom IC-7200.  But in the end, I’m so please with both radios I think it’s worth the investment.  Thankfully, the KXPA100 was not included in the Elecraft Black Friday sale. I did not need that temptation.

Post readers: Any others take a compact general coverage transceiver on travels? What model do you prefer?  Please comment!

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Escaping the noise while traveling

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A Sony SW100, a PK Loop, and a pint of L’Écurieux brown ale. Lovely trio!

If you’re a regular Post reader, you’re probably aware that I enjoy a relatively RFI-free environment at my rural mountain home. RFI-free living is something of a luxury, even though our rural location also equates to appallingly slow Internet service.

But unfortunately, when I travel, I usually find that I’ve traded my RFI-free atmosphere for the chaos of noise-ridden bands. If you’ve ever stayed at a modern hotel and tried to tune to anything on mediumwave or shortwave, you’ll know just what I mean.

We’ve spent this summer, like last, near Québec City, Canada.  Near this fairly large city, I’ve been greeted by more than enough RFI to make up for the lack of RFI most of the year.

I attribute the atrocious RFI to the number of light dimmers the developers put in this condo complex and the proximity to a field of noisy electrical poles. Of course, all of the unregulated power supplies in the area don’t help, either. It’s a jungle of noise.

The PK Loop

Last year, I purchased a PK Loop portable HF loop antenna (about $150 on eBay)–specifically with hotels and this very condo in mind. I must say, it has been a welcome travel companion on this trip.

The Elecraft KX2 and PK Loop

While the PK Loop seems to pair well with my Sony SW100, I also love using it with my Elecraft KX2 for SWLing.

Sadly, the PK Loop doesn’t provide the noise mitigation of a large wideband mag loop antenna–like a Wellbrook or Pixel Loop–but it does lend itself to excellent portability and takes the edge off the noise.

While it’s easy to do my radio listening in the condo from a comfy chair, in reality, it limits what I can receive in a serious way. The 31 meter band, for example, is so heavily submerged in RFI that only the strongest stations can punch through (for example, Voice of Greece, Radio Romania International, WRMI, WBCQ, Radio Havana Cuba, China Radio International).

So, what can I do?

Hit the field, of course!

That’s right. Taking a page from the books of SWLing Post contributors London Shortwave and Clint Gouveia, I realize I can simply leave the RFI behind and seek a sound, radio quiet spot for SWLing/DXing!

My listening post last year–during the BBC Midwinter broadcast–in the parking lot of St-Anne-de-Beaupré basilica.

Over the past two months, I’ve taken time to escape the RFI and do a few live listening sessions and spectrum recordings in the field. I’ve always got my SDRplay RSP, Elecraft KX2, and Sony ICG-SW100 at the ready. In terms of wire antennas, I’ve deployed my NASA PA30 and even my QRP Trail-Friendly EFT, with good results.

Listening to the 2017 BBC Antarctic Midwinter Broadcast from the back of my vehicle in Saint-Anne-de-Beaupré, Québec, Canada.

I’ve also been experimenting with the homebrew Miniwhip antenna that SWLing Post contributor, Steve Yothment, provided earlier this year, based on the design used by the U Twente WebSDR. As Guy Atkins recently demonstrated, miniwhip designs do require some distance from sources of RFI, however.

The field is your friend…

Just a friendly reminder that if you live in an RFI-dense environment, you can certainly design a system to help mitigate RFI at home. After all, home is where you likely spend the bulk of your free time.

View of the Saint Lawrence River from my back-of-the-minivan listening post.

But, again, the easiest way to substantially increase your chances of snagging DX stations is to simply hit the field.

Join me in giving it a try. Find an RFI-free location with access to a couple of trees to hang a simple wire antenna–say, in a park, at the side of a rural road, on a friend’s farm…and if you find the listening good, make it your radio get-away. You’ll likely find that your portable shortwave radio can outperform your at-home tabletop receiver simply by removing yourself and your radio from the noisy environ of indoors.

When you first start doing radio in the field, it might feel a bit awkward–especially if you’re taking more than a portable shortwave along for the ride–but you’ll soon enjoy the fresh air ambiance and maybe even prefer it to indoors.  Even if you’re in a public setting where curious passers-by may want to know what you’re doing, as they undoubtedly will…When questions arise, take a (brief!) moment to educate your questioner(s) about the fascinating and nearly-forgotten world of shortwave radio––maybe you’ll inspire others to listen in, too.

And trust me: once you’ve been to the field a few times, you’ll start to look forward to playing radio in the great–and noise-free–outdoors!

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Catch the 2017 BBC Antarctic Midwinter Broadcast?

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Listening to the 2017 BBC Antarctic Midwinter Broadcast from the back of my vehicle in Saint-Anne-de-Beaupré, Québec, Canada.

Yesterday afternoon, I packed up the Sony ICF-SW100, Audiomax SRW-710S and Elecraft KX2 portables in search of a quite spot to listen to the BBC World Service Antarctic Midwinter Broadcast. I also packed my PK Loop and NASA PA 30 antennas.

I’m traveling in Canada again and staying in an RFI-dense condo. There was no way I’d hear the broadcast through the noise, so I searched for a field location.

I discovered a quiet spot to park on the banks of the Saint Lawrence River in Sainte-Anne-de-Beaupré, Québec, Canada.

The location was almost ideal: it was RFI quiet compared to other spots I checked and I had access to a tree where I could hang the NASA PA 30 wire antenna.

View of the Saint Lawrence River from my back-of-the-minivan listening post.

Once I arrived, with little time to spare, I deployed the NASA PA 30 and connected it to my Elecraft KX2 transceiver. I then connected the Sony ICF-SW100 to the PK Loop antenna.

Since the KX2 is the most sensitive receiver in my travel arsenal–and even has built-in noise blanking, variable DSP noise reduction, and variable filter width–I used it as the source for my recording.

I checked audio levels by tuning the KX2 to the Voice of Greece on 9420–VOG was blowtorch strength.

None of the frequencies used for the Midwinter broadcast were ideal for my location and time of day (after all, these broadcasts target Antarctica!) but last year I did successfully receive the 41 meter band broadcast.

My fingers were crossed as the broadcast time approached (17:30 local/21:30 UTC).

A few seconds before the half hour, I heard the AM carrier light up on 7,360 kHz (ASCENSION). Very good sign! The broadcast audio followed a few seconds later and was weak, but intelligible. I would give the signal an overall SINPO of 35343.

I couldn’t receive a thing on the 6035 kHz (DHABAYYA) and only an extremely faint signal on 5985 kHz (WOOFFERTON).

The Elecraft KX2/NASA PA 30 combo did prove to be the most effective receiver/antenna pair.

I forgot to do two things in advance, however: to turn off the KX2’s key beeps (which would have been audible in the recording had I adjusted receiver settings) and to set my Zoom H2N to record in WAV format. Oh well…

I was very pleased with the results, all things considered.

The Sony ICF-SW100/PK Loop combo was also quite effective. The signal was a little weaker and less stable than the KX2, but I was still very pleased overall. Here’s a short video–note that I have the sync lock engaged:

Click here to view on YouTube.

The PK Loop was positioned on a folding trail seat close to the ground. After experimenting, I found that loop height had little impact on overall reception, so I opted to keep it closer for accessibility.

The PK Loop antenna.

Very impressive reception of weak DX for such a small portable a compact loop antenna. In the end, the SW100 is a phenomenal little DX machine!

I brought the Audiomax SRW-710S along as well. Since it has a built-in digital recording feature, I had hoped it might provide an additional recording of the broadcast.

Sadly, it fell short.

No matter how I positioned the receiver, nor what antenna it was connected to, the SRW-710S simply couldn’t cope with the weak signal, QRN and overall band conditions. The noise floor was high and the signal (when audible) very unstable. It was like listening to a battle between the receiver’s internal noise and the target signal.

The $20 Audiomax simply can’t compare to benchmark receivers like the ICF-SW100 and Elecraft KX2. Still, it’s an acceptable little radio for recording stronger shortwave, mediumwave and FM signals. I completely agree with Troy Riedel’s assessment.

Another Midwinter broadcast for the books!

It’s always a treat to enjoy the BBC Antarctic Midwinter Broadcast live, knowing that the BAS crew, wintering over in Antarctica, are enjoying it at the same time!

That, in a nutshell, is the magic of shortwave radio.

Please share your recordings!

I’ve already received a healthy number of recordings from SWLing Post readers!  Thank you so much!

If you have a recording of the 2017 Midwinter Broadcast that you’d like to submit, please do so by Sunday. I’m participating in Field Day and attending an airshow this weekend, but plan to publish a post with all of the recordings and your photos early next week.

Please send your recordings with any notes and photos to my email address which can be found on the Contact page. If you submit a video, please upload it to YouTube or Vimeo and simply send me the link. Thank you!

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A preliminary review of the PK Loop C-LOOP-HDSW6-18

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eecraft-kx3-pk-loop

The Elecraft KX3 and the PK Loop C-LOOP-HDSW6-18

Over the past year, a number of SWLing Post readers have asked me to review the PK Loop portable magnetic loop antenna produced by Paul Karlstrand in Australia.

I finally caved in and purchased one.

I ordered the shortwave version of the loop, the  C-LOOP-HDSW6-18 in early November and received it about one week later.

sony-sw100-pk-loop

The Sony SW100 tuned to WBCQ.

I was first introduced to this antenna by SWLing Post contributor, Mark Fahey, who brought it to the SWL Fest and our 2015 PARI DXpedition.

Mark has taken his PK Loops (both the shortwave and mediumwave models) on his numerous travels around the world. He finds that they’re relatively effective portable antennas in RFI-dense environments like hotels and guest houses. They’re better at mitigating RFI than, say, portable wire antennas or telescopic whips.

Mark hooks up his portable SDR to the PK Loop and makes spectrum recordings (wideband recordings)–from, say, his hotel room in Kuala Lumpur–then takes the recording back home to listen and tune at his leisure via his laptop or tablet PC.  While I’ve certainly made spectrum recordings while travelling in the past, the appeal of such a portable loop antenna is what finally caused me to pull the trigger.

Overview

pk-loop

The PK Loop is a small loop antenna–measuring about 12″ in diameter. It’s encased in UV-stabilized PVC conduit and the matching box also seems to be made of PVC. It feels very durable and can, no doubt, even survive the wildest of luggage handling.

The PK Loop has an attached battery 9V battery holder, but can actually be powered by any 9-18 volt DC supply. Current consumption is less than 15 mA. On the matching box, you’ll find a tuning knob, a BNC connector, DC power in port and a HI/LOW gain switch. My loop shipped with a 2 meter BNC-BNC Cable, 3.5mm adapter, and DC Power lead to open ends.

Operation

Operating the loop is very simple:

  1. Power the antenna with a 9V battery or other DC source
  2. Chose either the high or low gain setting
  3. Place it on a stable surface (height from the ground is not a critical issue, but you should avoid placing it next to noisy electronics or mobile phones)
  4. Connect the PK Loop to your receiver’s antenna jack with the supplied cable
  5. Turn on your receiver to the desired meter band, then adjust the loop’s tuning knob until you hear the signal level peak
  6. Start listening, keeping in mind that as you tune around the band you may need to adjust the loop’s tuning knob for maximum gain

Loop antennas, in general, are fairly narrow-band and–unlike a Wellbrook or Pixel Loop–manual adjustments need to be made with the tuning knob to match the PK Loop as you scan across bands.

Still, I see why Mark favors the PK Loop for spectrum recordings: the bandwidth is wide enough that if I tune the loop to the middle of the 31 meter band, for example, it does a fine job covering the entire band.

On the air

pk-loop-kx2-sw100

My free time has been very limited since receiving the PK Loop earlier this month, but over Thanksgiving holiday, I took it to my family’s home that has relatively high RFI levels.

The following are a couple of videos I made with my Moto X smartphone. I’ll be the first to admit that these are not the best videos–I had no tripod and the Moto’s microphone leaves much to be desired–but I think you’ll still get the idea of how well the PK Loop works.

With the Sony SW100

Click here to watch on YouTube.

With the Elecraft KX2

Click here to watch on YouTube.

So far, I’m very pleased with the PK Loop. It does seem to mitigate noise better than other portable antennas I’ve used in the past and certainly improves my SW100’s reception. It makes SWLing with the Elecraft KX2 or KX3 easy and convenient.

One word of caution: if you use the PK Loop with a transceiver like the KX2, please turn off the ATU, and set the power level to 0W before using. The PK Loop is receive-only and will not handle any RF power.

Note that with the SW100, I have only used the PK Loop’s low gain setting. I’m a little nervous about overloading the SW100, so do not plan to use the high gain setting. The Elecraft KX2 seems happy to handle either gain setting: I imagine this will be the case with most general coverage transceivers and tabletop receivers.

More to come!

In a couple of weeks, I’ll be staying in a hotel room (likely with inoperable windows and heavy RFI) so I will attempt to put the loop through its paces and compare it with my radio’s built-in antenna.  Stay tuned!

UPDATE: Click here to read my follow-up review.

Post readers: have you used the PK Loop or other similar portable/travel antennas? Please comment!

Click here to view PK’s Loop antennas on Paul Karlstrand’s website.

Paul also sells his antennas and ships internationally on eBay–click here to view the selection.

pks-loops

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