Portable antennas: a review of the Par Electronics EF-SWL

Last August and part of September, I traveled through the US with the CommRadio CR-1 and a couple of portable antennas: the Par Electronics EF-SWL and  NASA PA-30. I had the opportunity to try both in the field, and took notes as I used them. Following is a short review of the Par Electronics EF-SWL.

The EF-SWL ready to deploy.

The EF-SWL ready to deploy.

Par Electronics EF-SWL 

At the Dayton Hamvention last year, I had the pleasure of speaking with representatives of the North Carolina-based LNR Precision Inc. LNR is a mom-and-pop company with a focus on providing antennas, keys, and transceivers for the ham radio and shortwave listener markets.  Indeed I have several SWL friends who use on a daily basis an antenna this company manufactures and retails: the Par Electronics EF-SWL. LNR asked if I would consider reviewing their antenna, and since I was planning a road trip with radios in tow–the perfect opportunity to test such an antenna–I agreed.

The Par Electronics EF-SWL is an end-fed shortwave antenna designed for 1-30 MHz reception. It’s a receive only-antenna–perfect for the SWL. The radiator is 45 feet of #14 black polyethylene coated Flex-Weave wire. When I first used the EF-SWL, I noted the quality of its construction: no doubt it can withstand many deployments in all weather conditions–and it’s manufactured here in the US.

With a 45′ radiator, the EF-SWL needs a little space, but offers more gain than the other portable antenna I packed, the NASA PA-30 (look for its review in the near future). I put the EF-SWL to use in New Mexico where several large trees were readily available. I hooked the EF-SWL up to the CommRadio CR-1 and simply hung the end of the radiator as high as I could in a nearby tree. Though not a picture-perfect installation, it nonetheless certainly did the trick! I didn’t bother with a ground connection as I wasn’t in an area with much radio noise (RFI).

In the past, when setting up portable ham radio and shortwave listening, I’ve typically built my own antenna either for the specific meter band I hoped to use, or brought along a portable antenna tuner. It was quite nice having an antenna designed to be resonant on the broadcast bands.


Though I didn’t do this, I did noticed that the EF-SWL’s radiator is attached via a stainless stud–Par Electronics did this so you can remove the radiator and replace it with a different wire length. With the stock 45′ radiator, I still find the EF-SWL quite portable, especially when compared with most of the portable amateur radio antennas I use, which tend to take a dipole or delta loop configuration.

After returning from my trip, I decided to hook up the EF-SWL at my home base for longer-term evaluation. These past months I’ve had it on the air as an auxiliary antenna, and I’ve been impressed with its performance. In truth, it’s not in an optimal location hanging off the corner of my house, but I think this may actually represent with some accuracy the installation most SWLs will likewise be able to provide–in other words, placement that must factor in antenna restrictions or limited space. Of course, for any permanent installation, you will need to ground the EF-SWL for lower noise reception.

And yet, even in these suboptimal conditions, the antenna performs remarkably well.

As with any exterior antenna, of course, take precautions against lightening if you live in an area with thunder storms. If nothing else, at least disconnect the antenna when not in use.

Moving forward, I will plan to relocate the EF-SWL to a more ideal permanent location and most likely purchase another to keep in my antenna bag. I hope to use this antenna in a DXpedition I’ve planned later this year.

The EF-SWL retails for $75 US directly from LNR Pecision or $72 US from Universal Radio.

Note that LNR also sells a number of QRP field-portable transceivers: the LD-5, FX-4a and Mountain TopperClick here for more details.

Chrome Remote Desktop: another application choice


In response to my post about SWLing in a hospital waiting room via TeamViewer, Stephen Cooper comments:

“Google Chrome Remote Desktop also works well for this.

[Click here to download]

Allows me to listen to my Elad when I am in work. Although it doesn’t transfer sound on Android (not sure about iPad) which isnt that good if you haven’t got a PC/Mac to use to login to home.”

Thanks for the suggestion, Stephen!

Shortwave listening in a hospital lobby


This morning, at 6:00 am, I had to take a friend to the hospital for a scheduled (minor) operation.

The hospital waiting room is spartan for a projected three hour wait, but the complimentary wi-fi Internet is quite speedy. I had planned to catch up on a movie or two via Netflix, but the hospital blocks video streaming.

Fortunately, I just noticed that the hospital does not block TeamViewer–my remote PC application of choice.

Remote listening

I just logged into my home PC and launched both the Elad FDM-S2 and WinRadio Excabur SDR applications–fortunately, I discovered that the Excalibur was hooked up to an external antenna.

Not only does TeamViewer allow me to control a software defined radio, but it actually streams the receiver audio from my PC. With my inexpensive in-ear Sony headphones, the sound isolation and audio fidelity are quite good for a compressed audio stream. Indeed, other than a one second delay in response, the user experience is nearly as good as being home.

I should note that I could also use the TeamViewer app on my iPhone, but 4G reception in the hospital is very poor and controlling an SDR from a small touch screen is less than desirable (though works in a pinch–no pun intended).

I’m currently tuned and listening to Radio Australia, Radio Mali and the Voice of Korea.

The 31 meter band seems to be wide open at this morning. At this point, I don’t think I care if my friend’s out-patient procedure takes a while longer!

Radio Australia: SWLing in the Colorado Rockies

Sony-ICF-SW7600GR-RA-CO I’m in Keystone, Colorado at about 9,300′ (2,835 M) above sea level; mornings are crisp and chilly (38F/3C), but that doesn’t stop me from putting on a jacket, heading to the balcony and listening to Radio Australia on 9,580 kHz. Despite flaky solar conditions (flaky, frankly, is an understatement) I managed to snag RA Wednesday morning (13:58 UTC) on my Sony ICF-SW7600GR. There was a little fading, and a little local noise, but overall signal quality was quite good.

gnav_logoThis recording starts a couple of minutes before the top of the hour; you’ll hear the TOTH news brief and then triple ja brilliant show dedicated to new Australian music.

Click here to download the recording as an MP3, or simply listen via the embedded player below:

Listening to WWV at the source: Fort Collins, Colorado, USA

MysterySW-site-LTIf you haven’t already guessed it: yes, the mystery broadcast site I posted on Thursday was WWV/WWVB in Fort Collins, Colorado. Well done, responders!  Specifically, the photo shows the southern antennas of WWVB as I departed the site on Thursday, August 28, 2014; for those of you who got that detail, extra credit–!

I’d like to thank the staff at WWV/WWVB for allowing me to visit the site for the better part of the day. WWV is not officially open to tours, so this was a particular honor for me. And this was an especially fun pilgrimage, as WWV was most likely the first shortwave broadcast I ever heard:  as I’ve previously noted, when I was a kid my father used to set his watch to WWV every Sunday morning.  Now I’ve seen firsthand where that famous tock, tock (and accompanying characteristic tones) originate.

When I return home from my extended travels, I’ll sort through the photos I took at WWV and WWVB, and post them here on the SWLing Post.

Recording WWV

In the meantime, I have a few recordings to share with those who are interested in this mecca of chronology.  Before leaving WWV, I pulled out my Tecsun PL-380 and my Zoom H2N digital recorder, and recorded all the WWV broadcast frequencies. I captured their 2.5, 5, 10, 15, 20 and even their recently reactivated 25 MHz signals.

I made these recordings in the conference room at WWVB broadcast house. As you can imagine, it was simply not at all necessary to extend the telescopic antenna. In fact, the signal was so strong, you’ll hear a slight amount of distortion in the voice audio.


Below, you can listen to the recordings of each frequency via the embedded player (click on the title to download the audio). Enjoy!

WWV on 2.5 MHz

WWV on 5 MHz

WWV on 10 MHz

WWV on 15 MHz (includes top of the hour station ID)

WWV on 20 MHz

Up to this point, I used the Tecsun PL-380, but quickly realized that the ‘380 wouldn’t tune to 25 MHz. A quick look at the back of the radio revealed that the ‘380 only tunes up to 21.950 MHz (!). Believe it or not, I’d never noticed this limitation of the PL-380, likely since I rarely tune above 21 MHz for broadcast listening.  Learn something new every day…But I couldn’t fail to complete my recordings.



So what did I do? I turned to Matthew Deutch, Chief Engineer at WWV and WWVB, who kindly allowed me to use their Sangean ATS-505 to make the final recording:

WWV on 25 MHz (includes Atlantic and Pacific weather)

London Shortwave refines his tablet-based portable SDR

IMG_0248 (1)

One of the great things about the SWLing Post is that readers share their varied–and highly creative–methods of playing radio.  A few weeks ago, SWLing Post reader, London Shortwave, shared his portable SDR set-up with us; he uses this outdoors to mitigate London’s heavy radio interference. Dennis Walter, president of Germany-based Bonito, commented, and later posted an alternative portable SDR solution using the Bonito RadioJet IF receiver.

Below, London Shortwave shares a guest post (also viewable on his blog) which describes in detail his design for his portable SDR around the FunCube Dongle Pro+ and an 8″ Windows tablet, and explains how effectively it works for him. This post includes recordings and a video; it’s an excellent tutorial:


This article is a follow up to the submission I made to the SWLing Post a little while ago. In short, the idea was to combine the FunCube Dongle Pro+ USB-based software defined radio (SDR) with an 8″ Windows tablet running SDR# to have a portable, on-the-go SDR solution.

The original inspiration

The original inspiration

Tablet radio interference

At the outset, I thought that all that was necessary was a tablet (I chose Toshiba Encore 8″), the FunCube dongle itself and just some antenna wire. This turned out to be a naive assumption because the tablet’s USB interface injected enormous amounts of radio frequency interference (RFI) into the SDR, making listening on some shortwave frequencies essentially impossible. Just to be sure that I wasn’t being plagued by a defect of my chosen tablet model, I tried out the same set-up on a Dell Venue 8, with identical results.

To deal with the issue of tablet-generated RFI, I bought a galvanic USB isolator, which, in essence, is a box that breaks the electrical connection between the USB dongle and the tablet’s USB interface while allowing USB data to pass through in both directions.

Heros Technology galvanic USB isolator

Heros Technology galvanic USB isolator

Additional power for the SDR


The isolator resolved the RFI issue completely, but created another problem altogether: the device specifications state that the isolator’s power output is restricted to 100mA at 5V. This is sufficient for USB devices that are self-powered but not for the FunCube dongle that draws all of its power from the USB port to which it is connected.

USB Y cable

USB Y cable

One way to supply extra power to a USB device is to use a “Y-cable”. Such cables have one extra USB plug that can be attached to a source of additional power (for example, a USB power bank). This solution is commonly used to connect power-hungry items, such as large hard disks, to low-power, portable computing devices (laptops and tablets). Having bought this cable, my next step was to find/improvise a battery that meets the USB power specifications (5V, 500mA).

Yet more interference

My first thought was to use the mobile USB power bank that I use to charge my iPhone while on the go. After all, it already has a USB port and supplies power with the right voltage. Once again, my expectations were confounded and RFI reared its ugly head! The power bank radiates significant interference into the circuit because it uses a switching regulator to maintain steady voltage. Luckily, I came across Gomadic’s portable AA battery pack with regulated 5V output that emits way less interference than any of the other USB batteries I tried (my intermediate solution used 4 rechargeable AA batteries and a makeshift USB connector, and although this resulted in zero additional interference I decided that it’s not safe to supply the SDR with unregulated voltage that doesn’t match the rest of the circuit). I used the handy passthrough USB voltmeter I bought in Maplin to check that Gomadic’s nice-looking gadget does indeed give out 5V as advertised.

So, what can one do with the remaining RFI from the additional power supply? It turns out that it can be mitigated quite effectively by inserting a balun (item 10 on Figure 2) between the SDR and the antenna wire (item 12). The balun is connected to the SDR with a coaxial cable (the “feed line”, item 11). Additionally, ferrite choke rings (item 9) attached to the feed line help reduce this RFI further: winding the feed line through the choke rings several times is sufficient. However, neither the balun nor the chokes are effective enough to replace the USB isolator! It appears they only help with the noise generated by the power supply, which is relatively minor anyway.

 Cost vs Portability

When SWLing Post published the details of my intermediate solution, Dennis Walter – one of the engineers behind Bonito RadioJet – popped up in the comments section and suggested that my setup is too tedious, as it involves lots of cables, and that his SDR is superior in terms of portability and the supplied software. While I haven’t had the chance to evaluate RadioJet, I pointed out that the cost of his radio is significantly higher than that of all of my components put together. I also mentioned that the free SDR# software I use is superb: it sounds excellent and offers a number of features that many software packages and conventional radios don’t have. So, having finalised my design, I thought that it might be time to tally up the cost and listen to the results.

Below is the full component list:

1) Toshiba Encore 8″ tablet $194

2) On The Go USB host cable for Toshiba’s micro USB connector: $7

3) Heros Technology USB Isolator: $125

4) USB Y cable with two males + 1 female plugs: $8

5) Gomadic Portable AA Battery Pack with regulated 5V output: $20

6) Gomadic female USB connector tip: $6

7) FunCube Dongle Pro+: $208

8) USB volt-meter (optional): $33

9) 2 ferrite choke rings: $10

10) Wellbrook HF Balun: $50

11) Feedline cables $7

12) 6 metres of thick copper antenna wire: $8

Adding up the prices of items 2 – 12 (and excluding the optional voltmeter) brings the total cost to  $449 vs. Bonito RadioJet’s $689. For the price difference you can throw in the Toshiba tablet at $194 and still have some change, enough to buy a carrier bag and perhaps even a nice pair of headphones!

Figure 1. Radio components

Figure 1. Radio components

Figure 2. Antenna components

Figure 2. Antenna components

In terms of portability, the entire setup fits nicely into an 11″ laptop carrier bag.

Figure 3. Packing the components into an 11" carrier bag

Figure 3. Packing the components into an 11″ carrier bag

Figure 4. Ready to go

Figure 4. Ready to go

Setting things up in the field is not particularly cumbersome, either:

Figure 5. Portable SDR setup in action in a local park

Figure 5. Portable SDR setup in action in a local park

As for the results, listen to the below snippets and be the judge. The only thing I will say is that none of my other portable radios have ever given me this kind of performance, not even with the long wire antenna attached:

And while we’re at it, here’s a demo video:

Portable SDR on Toshiba Encore 8″ Tablet from London Shortwave on Vimeo.

At one point I wanted to build an enclosure to house the FunCube dongle, the power supply and the USB isolator in a single tidy unit, but I no longer see the need. It’s easy to pack all of those items into the carrier bag and also they are all useful individually: the USB isolator can be paired with other SDRs, and I recently discovered a neat additional use for the Gomadic battery pack.

Well, that brings me to the end of this post. I hope my design will inspire you to come up with your own portable SDR system, and that you will share your results with me in the comments section. Happy listening!


SWLing in New Mexico: Radio Australia


This morning, I was very happy to tune to Saturday Night Country on Radio Australia (9,580 kHz). RA’s signal was booming into Taos, New Mexico, where my travels have taken me this Saturday morning.

It was a welcome relief to hear RA; the shortwave bands have been in terrible shape the past three days or so. The ionosphere has been so disturbed that the only broadcasters I’ve been able to hear have been Radio Havana Cuba and a few domestic religious broadcasters.

I hope to take the CommRadio CR-1 out later today and perhaps test a couple of outdoor antennas…Stay tuned!