Tag Archives: Matt Blaze

The “Signal Sweeper”: How to build a portable Wellbrook loop antenna

Many thanks to SWLing Post contributor, Matt Blaze, for the following guest post:


The “Signal Sweeper”, a portable Wellbrook antenna setup

by Matt Blaze

Here’s a very simple construction project that’s really improved my travel shortwave and mediumwave listening experience.

When I go somewhere interesting (whether a day trip on my bike or a longer excursion to an exotic locale), the two things I’m sure to want with me are my camera gear and at least one good receiver. Fortunately, there are plenty of good quality shortwave receivers to choose from these days; the hard part is packing a suitably portable antenna that can do justice to the signals wherever it is I’m going.

I’ve long had a Wellbrook antenna on my roof at home. These wide-band amplified loops famously enjoy a reputation for excellent intermod and noise rejection, as well as an almost magical ability to pull in signals comparable to much larger traditional HF and MF receive antennas. A portable Wellbrook – something I could pack in my luggage that performs as well as the one on my roof, would be just ideal.

Fortunately, Wellbrook sells a “flex” version of their antenna intended for just this application, the model FLX1530LN. It’s essentially just the amplifier of their fixed-mount antennas, equipped with a pair of BNC connectors for you to attach a user-supplied ring of coaxial cable that serves as the antenna loop. This way, you don’t need to travel with the awkwardly large 1 meter diameter ring of aluminum tubing that makes up the normal Wellbrook. You can just bring a compact spool of coaxial cable and configure a loop out of it when you arrive at your destination.

The tricky part is how to actually form a stable loop out of coaxial cable without needing lot of unwieldy supporting hardware. In particularly, I wanted something that could be set up on a camera tripod to be freestanding and easily rotated wherever I happened to find myself wanting to play radio. The key would be finding or making some kind of mostly non-metalic support for the coaxial loop that could be folded down or collapsed to fit in my baggage or backpack for travel.

And then I found it: a humble 3-section telescoping broom handle sold on Amazon for about $15 that’s exactly the right size: the “O-Cedar Easywring Spin Mop Telescopic Replacement Handle“. It collapses to 22 inches (just short enough to fit in my suitcase), and extends to 48 inches (comfortably long enough for a one meter diameter loop).

Normally, a wire loop would need both vertical and horizontal supports in a cross configuration, but by using a reasonably stiff coaxial cable, I figured I could get away with just using the broom handle vertically. I found that LMR400 (the basic kind, not the “Ultraflex” version) holds its shape quite well in a one meter loop supported this way.

At this point, it was just a matter of the details of attaching and mounting everything together into a portable package.

A one meter diameter loop, which is the ideal size for the Wellbrook amp, can be made from 3.14 meters of cable (ask your middle-school math teacher). That’s about 10 feet for Americans like me. High precision is not required here, so I just cut 10 feet of LMR400.

The next step is to attach the middle of the cable to the top of the broom handle. The O-Cedar handle has a loop at the end for hanging it on a hook in your broom closet. It happens to be just the right diameter for LMR400, but not with BNC connectors attached. So you’ll have to thread the cable through before you crimp or solder on the with connectors. (See photo above). I used the Times Microwave crimp-on BNC connectors, which I had some extras of lying around. I also put some shrink wrap on the cable at either side of the broom loop, just to keep it from slipping out and becoming unbalanced, but that was probably unnecessary.

Now I needed a way to to attach the Wellbrook amplifier to the other end of the handle, as well as some way of mounting the whole thing to a camera tripod. My first thought involved a lot of duct tape. But I wanted something more permanent and reusable.

The key is something called an “L-Plate”, which is a piece of hardware intended to allow you to mount a camera to a tripod in either “landscape” or “portrait” mode. It’s basically two tripod dovetail mounts attached at a 90 degree angle. I used one that was in my junk box, but you can buy them new or used on eBay. I also needed a clamp to attach the L-plate to the broom handle. I used the Novoflex MiniClamp 26, which I got from B&H Photo. The clamp attaches to the inside of the L-plate with a captive screw. (See photos)

Next, I attached the amplifier to the other side of the L-plate using an ordinary screw-on hose clamp. Easy enough, and surprisingly sturdy.

And that’s it. To assemble the antenna, just extend the broom handle to about one meter, allowing for a roughly one meter diameter loop that’s as round as you can make it with the amplifier at the bottom. Then clamp the L-plate to the bottom of the handle so that the handle is just above the base of the plate, and attach to the tripod. (See the photos).

The Wellbrook is powered over the feedline with a 12VDC bias-T injector. So you need a clean source of 12 volts. I use a cheap Talent Cell battery pack (available on Amazon in various capacities). These actually deliver 11.1 VDC (3x 3.7V), rather than the 12V the Wellbrook calls for, but it works fine in practice. I can also use the same pack to power the radio and digital audio recorder.

In the photos, you can see the finished antenna setup on my roof, with my permanent base Wellbrook on the rotor in the background. The performance of the two antennas is quite comparable.

(Note that there’s an eBay seller that makes a somewhat similar travel loop. The performance is quite good under normal conditions, but it is a bit more subject to MW overload when near a transmitter site. So I prefer the Wellbrook, which is much less susceptible to overload, I’ve found.)

My usual complete travel setup is either a Reuter RDR Pocket C2 radio or a Sangean ATX-909X (recently upgraded to the X2 model). Both these radios work well with the Wellbrook. I use a Sound Devices Mixpre 3 to record airchecks in the field. In the photos, I’m on a rooftop DXpedition listening to Toronto traffic and weather from CFRX on 6070 kHz on a warm later winter afternoon.

The whole setup breaks down for travel pretty easily, and fits easily in my suitcase, backpack, or bike bag (see photos). I usually bring a larger tripod than this if I’m also taking my camera.

The Wellbrook setup has really made bringing a receiver into the field a lot easier and less uncertain. There’s no worry about finding trees or other supports for wires, and packing and unpacking is quick and easy. Have fun!

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Transmitters stuck in time

Sometimes we radio enthusiasts discover odd things on the air.

We’re listeners and we notice things.

A few days ago our friendy, Matt Blaze, tweeted this:

Yep, for eight years a DDOT TIS (Traffic Information System) transmitter has been broadcasting the same repeating message and few have noticed.

You can read Matt’s whole Twitter chain here.

Matt has also kindly shared an audio recording of this transmitter. He notes that the reception “was weak but readable” from his home:

What’s more, Matt’s tweet was picked up by The Drive and turned into a post, thus exposing our radio geekery to the populos at large. Many thanks to the numerous SWLing Post readers who shared a link to the article.

I have to assume someone from the DDOT was paying attention too because Matt posted that as of March 3rd, it appears the transmitter has been taken off the air:

This reminded me of another transmitter stuck in time that I thought David Goren once mentioned. I checked with him and he confirmed:

Yes, there’s a transmitter somewhere on MW in NYC that has been broadcasting: “this is a functional test of the text-to-speech capability of the [VR or BR 2000] software package”. They’ve probably been on at least 10 years.

Many thanks to David for sharing the following recording:

Have you ever heard a forgotten transmitter? Please comment with details!

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Matt’s Monster Mediumwave Radio Selectivity Shootout!

Many thanks to SWLing Post contributor, Matt Blaze (WB2SRI), for sharing another brilliant audio comparison featuring benchmark portable radios:


Medium wave selectivity shootout

by Matt Blaze

I did another monster medium wave portable receiver comparison, this time with the aim of comparing receivers’ ability to deal with weak signals in the presence of strong adjacent channels.

Once again, I went up to the roof with eight MW portables with built-in antennas and recorded them simultaneously along with my “reference signal”, from an Icom R-9500 with an active loop on the roof. As before, I recorded a narrated stereo mix with the Icom on the left and the rotation of radios for a minute or two each on the right, but have “solo” tracks available for the full time for each radio. The nine receivers in the lineup this time included:

  • Icom R-9500 (with amplified Wellbrook loop antenna on roof)
  • Potomac Instruments FIM-41 Field Intensity Meter (my personal favorite)
  • Panasonic RF-2200
  • Sony IC-EX5MK2
  • C.Crane Radio 2E
  • Sangean PR-D4W
  • Sangean ATS-909X
  • Tecsun PL-990X
  • XHDATA D-808

I recorded two signals, one at night and one during the day.

Nighttime Signals

The first was at night: WWL New Orleans on 870 KHz. This signal is usually weak to medium strength here, but is a challenge for two reasons: first, it shares the frequency with Cuba’s Radio Reloj, and it is squeezed between two much higher strength signals: Toronto’s CJBC on 860, and NYC’s WCBS on 880. So you need a decent receiver and careful antenna orientation to receive it well here. That said, everything did pretty well, though you can see that some radios did better than others.

The mix

Solo tracks

Icom IC-R9500

Potomac Instruments FIM-41 Field Intensity Meter

Panasonic RF-2200

Sony IC-EX5MK2

C.Crane Radio 2E

Sangean PR-D4W

Sangean ATS-909X

Tecsun PL-990X

XHDATA D-808

Daytime Signals

The second signal was during the day and was MUCH more marginal: WRJR Claremont, VA on 670 KHz. This was real challenge for any receiver and antenna. The signal was weak, and overshadowed by WCBM Baltimore on 680, a 50KW daytimer that is very strong here. (I’m not 100% sure that we were actually listening to WRJR – I never got an ID, but the station format and signal bearing was right). We can really hear some differences between the radios here.

The mix

Solo tracks

Icom IC-R9500

Potomac Instruments FIM-41 Field Intensity Meter

Panasonic RF-2200

Sony IC-EX5MK2

C.Crane Radio 2E

Sangean PR-D4W

Sangean ATS-909X

Tecsun PL-990X

XHDATA D-808

Everything (except the Icom) was powered by batteries and used the internal MW wave antenna, oriented for best reception by ear (not just maximizing signal strength, but also nulling any interference). The loop for the Icom was similarly oriented for best intelligibility.

For audio nerds: The recording setup involved a lot of gear, but made it fairly easy to manage capturing so many inputs at once. The portable radios were all connected to a Sound Devices 788T recorder, with levels controlled by a CL-9 linear mixing board control surface. This both recorded the solo tracks for the portables as well as providing a rotating mix signal for each receiver that was sent to the next recorder in the chain, a Sound Devices 833. The 833 received the mix audio from the 788T, which went directly to the right channel. The left channel on the 833 got audio from a Lectrosonics 822 digital wireless receiver, which had the feed from the Icom R-9500 in the shack (via a Lectrosonics DBu transmitter). The center channel on the 833 for narration of the mix, which I did with a Coles 4104B noise-canceling ribbon mic. This let me record fairly clean audio in spite of a fairly noisy environment with some wind.

All the radio tracks were recorded directly off the radios’ audio line outputs, or, if no line out was available, from the speaker/headphone jack through a “direct box” interface. I tried to make the levels as close to equal as I could, but varied band conditions and different receiver AGC characteristics made it difficult to be completely consistent.

Making the recordings was pretty easy once it was set up, but it did involve a turning a lot of knobs and moving faders in real time. I must have looked like some kind of mad scientist DJ to my neighbors, some of whom looked at me oddly from their own roofs.

Happy Thanksgiving weekend!


Thank you, Matt, for another brilliant audio comparison! I appreciate the attention and care you put into setting up and performing these comparisons–not an easy task to say the least. That Potomac Instruments FIM-41 is an impressive machine!

By the way, I consider it a badge of honor when the neighbors look at me as if I’m a mad scientist. I’m willing to bet this wasn’t your first time! 🙂

Post readers: If you like this audio comparison, please check out Matt’s previous posts as well:

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Matt’s Marathon MediumWave Matchup

Many thanks to SWLing Post contributor, Matt Blaze (WB2SRI), who shares the following guest post:


Matt’s Marathon MediumWave Matchup

by Matt Blaze

Here’s another simultaneous receiver comparison, this time of ten portable medium wave receivers plus the Icom IC-R9500 (as a “reference receiver”). Previously, I used the same antenna for all the comparisons, but since these are portable receivers, I wanted to compare their performance using their built-in antennas. I did two comparisons, both of moderate to weak signals, one in the evening of a DX signal and the other in the daytime of a regional station.

The receivers were the Potomac Instruments FIM-41 (a “field intensity meter”), the Panasonic RF-2200, the Nordmende GlobeTraveler Exec (a beautiful German SW portable from 1968), the Sony ICF-EX5MK2, the CCrane Radio 2E, the Sangean ATS-909X, the Sangean D4W, the new Tecsun PL-990X, the XHDATA D-808, and finally the CountyComm GP5-SSB, plus the Icom IC-R9500.

All the receivers were recorded simultaneously. The radios (except the Icom R9500) were on the roof of my building and oriented for best reception (signal/noise) and kept sufficiently away from each other and other metal objects to avoid interference, The R9500 was in the shack and used a Wellbrook loop on the roof, also oriented for best signal/noise. I took the audio from the Line Out if one was available and from the headphone jack (via a “direct box” level converter) if not. I tried to match the audio levels reasonably closely, but different ACG characteristics made it difficult to be completely consistent across all the receivers throughout the sessions.

As in previous comparisons, for each session I’ve got a narrated stereo mix with the R9500 on the left channel and each receiver, for a minute or so one after the other on the right channel. You definitely want to use headphones to listen to these so you easily tell the left from the right radio. I’ve also provided mono “solo” recordings of each receiver for the full 15 minute-ish sessions so you can hear a receiver you’re interested in in detail.

Sound Devices 688 Multitrack Recorder

The recordings were made with a Sound Devices 688 recorder/mixer (which can record 12 simultaneous channels of audio). The portable radios were hardwired to the recorder, and the 9500 (which was downstairs) was connected via a Lectrosonics digital radio link. (Everything except the R9500 was on battery power to avoid mutual interference and ground loops, etc). The narration used a Coles noise canceling ribbon mic. Everything was done in a single take per session – there was NO postproduction editing – so I apologize for a few glitches and awkward moments.

You can see a “class photo” of the setup below, although the position and orientation of the radios was different during the actual recordings.

KCJJ

The first recording was at night, where we tuned to 1630 KCJJ in Iowa City, IA. This is effectively a 1KW clear channel; other than a few TIS stations, there’s not much else there on the east coast, and the signal is reliably weak to moderate but readable here on the east coast.

Narrated L/R stereo comparison:

Individual solo tracks:

CCrane Radio 2E

Sangean D4W

XHDATA D-808

Sony ICF-EX5MK2

Potomac Instruments FIM-41

CountyComm GP5-SSB

Nordmende GlobeTraveler Exec

Tecsun PL-990X

Icom IC-R9500

Panasonic RF-2200

Sangean ATS-909X


WSVA

The next recording was made during the day, of WSVA, a regional station in Harrisonburg, VA running 5KW in the daytime. Their signal is also reliably weak-moderate but readable here.

Narrated L/R stereo comparison:

Individual solo tracks (receiver should be obvious from the file name):

CCrane Radio 2E

Sangean D4W

XHDATA D-808

Sony ICF-EX5MK2

Potomac Instruments FIM-41

CountyComm GP5-SSB

Nordmende GlobeTraveler Exec

Tecsun PL-990X

Icom IC-R9500

Panasonic RF-2200

Sangean ATS-909X

Hope your readers find it useful!

-matt


An absolutely amazing job again, Matt! Thank you so much for taking the time to put this comparison together and sharing it here on the SWLing Post.  

Click here to check out all of Matt’s receiver audio comparisons.

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Matt’s mediumwave audio comparison of the C.Crane Radio 2E and the Potomac Instruments FIM-41

Many thanks to SWLing Post contributor, Matt Blaze, who writes:

I did another head-to-head receiver comparison, this time of two MW BCB AM portables: The C.Crane Radio 2/e vs. the Potomac Instruments FIM-41 field intensity meter.

The latter is not intended as a receiver, but rather a test instrument, but it turns out to be the among most sensitive MW receivers I’ve ever used. So I thought it would be interesting to compare its performance with that of a well-regarded modern portable.

Audio Comparison:

Our two contenders with comparable portable radios: the GE Super Radio, Panasonic RF-2200, and Sony ICF-EX5MK2.

Another brilliant audio comparison, Matt! Thank you so much for taking the time to put this together! I actually believe audio comparisons, as you’ve set them up, are a fantastic way of sharing A/B comparisons.

Click here to check out all of Matt’s receiver audio comparisons.

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Matt compares the Tecsun PL-990 and Sangean ATS-909X sharing an external antenna

Many thanks to SWLing Post contributor, Matt Blaze, who shares the following comparison of the new Tecsun PL-990x and the original Sangean ATS-909X communications receivers.

Like Matt’s recent comparison of the Tecsun PL-990x to the Icom IC-R9500, this review is in audio form and brilliantly narrated by Matt. I highly recommend listening with headphones or, at least, an audio device with separate left/right channels as his comparison takes advantage of this.

Enjoy:

Yet another superb presentation, Matt! Thank you so much for taking the time to make these audio comparison tests.

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Matt compares the Tecsun PL-990 to the Icom IC-R9500 on an external antenna and the results are surprising

Many thanks to SWLing Post contributor, Matt Blaze, who shares the following comparison of the new Tecsun PL-990x and the benchmark Icom IC-R9500 communications receiver.

Matt’s excellent comparison  is in audio form. I highly recommend listening with headphones or, at least, an audio device with separate left/right channels as his comparison takes advantage of this.

I love not only how he set up this comparison with both radios sharing an identical antenna, but his evaluation also explores how well the PL-990 handles a proper external antenna via its external antenna jack.

Click below to listen to Matt’s piece, or right click here to download the audio:

Thanks for sharing this, Matt. You’ve inspired me to do similar narrated audio comparisons!

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