Category Archives: Accessories

Martin builds a simple ferrite rod to inductively couple radios to his external mediumwave antenna

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Many thanks to SWLing Post contributor, Martin Tobisch, who shares the following guest post and videos from his home in Malta:

New AM Signal Coupler

Many AM medium wave listeners are looking for solutions to improve the reception performance of their radios.

After many attempts, which I don’t want to entertain anyone with, a coupler was created that feeds the external antenna directly into the ferrite antenna. I use my 66 foot long wire antenna on 50 ohm RG-58 cable, but other antennas will have similar success.

The clips available on YouTube speak for themselves:

https://youtu.be/FIylJk3F9Xk?si=Kp7SowdUXI5i5QAV

https://youtu.be/RHAla9jPoi8?si=VoG3w274k08Ul8Q4

 

Experiments with smaller ferrites and antenna rods met with no success. It is important that the coupler still works even at a distance from the ferrite antenna and without precise alignment.

With tube radios it easily bridges the distance from the housing to the ferrite rod Antenna
The finished coupler consists of 6 NiZn ferrite cores, which are connected with glue to form a rod. 8 turns of wire are wound over this and soldered to an RG-58 cable. Some electrical isolation tape and ready. So far I’ve just put it in a box. Of course there are finer solutions and it should be protected against shock. Ferrite cores are notoriously brittle.

Here is a link to the ferrites used (purchased at AliExpress).

Advantages: Advantages to what? Nothing comparable exists.

So there are advantages to feeding via an antenna socket. The signal coupler is also good for radios without an antenna socket. But in case of using an antenna socket, common mode wave interference picked up in the house goes unlimited into the radio. Due to the magnetic coupling to the ferrite antenna, common mode waves are completely suppressed. They do not create a magnetic field in the coupler.

No changes are necessary in the radio

The biggest advantage is, that you can listen to distant stations loud and clear, which previously only produced a quiet scratching noise.

I very much welcome reports of experiences.

[email protected]

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Guest Post: Here Come the Lithiums

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Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following:

Power Play – Here Come the Lithiums

by Bob Colegrove

I have belonged to several radio-oriented user groups in recent years and can’t help noticing how often the subject of batteries comes up.  It’s almost a sub-hobby within the hobby.  There are a couple of reasons for this, first is the unending quest for the ultimate cost-effective, everlasting battery, and second, it’s a rare opportunity for most of us to tinker in an increasingly complex world of technology.

Lithium batteries offer a sustainable voltage output well into their discharge cycle and can deliver a higher rate of current than alkaline batteries.  They are somewhat lighter in weight than alkaline batteries – 2.5 oz. versus 5 oz. for D-cells.

Considering the fast pace of technology, lithium batteries have been with us for a comparatively long time, this in the form of cell phone and camera power, not to mention a host of electric appliances.  Most of these batteries have limited purpose, that is they have been developed and packaged for just a few applications, thus resulting in an incredible variety of sizes and shapes, and no doubt a host of frustrations due to obsolescence.  It’s somewhat reminiscent of the early days of transistor radios which ran on a wide array of zinc-carbon batteries.

Perhaps I have been asleep at the wheel, but it has only come to my attention recently that lithium chemistry has begun to backfill the standard battery sizes we have long been familiar with, namely AAA, AA, C, D, and even the PP3 standard 9 volt.

I have been running along quite successfully for more than 10 years on AA NiMH technology on several portable radios.  Although these run at a slightly lower cell voltage of 1.25 Vdc, the one-for-one substitution of these for alkaline chemistry has seldom been a problem in terms of performance.  In most cases, newer radios are provided with an alkaline/NiMH-NiCad setting to compensate for the difference in voltage.  Even the venerable Sony ICF SW7600GR, for which alkaline batteries are assumed, seems to operate equally well either way.

My problem has always been the larger power consumers running on D-cells – the Sony ICF 2010 and Grundig Satellit 800 to cite two examples.  A fresh set of NiMH batteries put the 2010 on the cusp of poor performance.  Lithium batteries having a sustainable single-cell voltage of 1.5 Vdc now provide a possible alternative to a steady diet of costly alkaline cells.  Even more attractive, some are equipped with a USB-C connector and can be recharged without a dedicated charger.

In the figure above, a set of four lithium D cells are connected simultaneously through a 4-lead USB-C harness and USB charger (not shown).  Many of the brands include the harness with a set of batteries.  I have added a USB multimeter, which I find very useful to monitor the progress of the charge, but this is not necessary.  This particular meter can also show accumulated capacity.  However, it should be noted that, unless batteries are charged one at a time, charging rate and capacity will show the total values for the number of batteries being charged.  I would also recommend that the USB charger be rated at least 3 amps.  In the figure below, one of the USB-C leads is connected at the top of the battery.  The built-in LED flashes during charge and remains on when the charge is complete.

Cost is an equally important consideration.  There is a lot of hype in the marketing department about how many times these batteries can be recharged.  The key compound preposition here is “up to,” and as long as they use those words, they can make the number anything they want to.  That said, it simply won’t take more than a few cycles for the cost-benefit cusp to be reached in favor of lithium batteries.

I am just getting started with this.  Although the batteries came highly recommended for the portable radio application, I can make no judgment at this time as to their ultimate quality or convenience.  It just seems like the next logical way to go.

There are some things to remember when choosing lithium batteries.  Not all lithium batteries are rechargeable, particularly smaller sizes.  Some do not come with the built-in USB-C charging jack, so a separate charger intended for lithium batteries will be required.  D size batteries are also available at 3.6 Vdc/cell.  There may be other options, so watch out.  Be sure to thoroughly check the features of any batteries you consider.

I would close by warning that lithium batteries come with safety caveats regarding their transport, handling, use, charging, and disposal.  These precautions are all well stated in the literature, which should be followed with an abundance of caution.  Of note is the fact that not all chargers support lithium batteries, and their capability should be checked as well.

Click here to check out these Lithium D Cells on Amazon.com (SWLing Post affiliate link), or explore other brands.

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High Noon: Belka MW shootout part 2, with a review of the AFA200C active MW ferrite antenna

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High Noon: Belka MW shootout part 2, with a review of the AFA200C active MW ferrite antenna

by 13dka

When I reviewed the updated Belka (gen3, 2022) for its MW/LW performance in October last year, I just wanted to know if it’s any good with just the whip antenna and used the XHDATA D-808 as a reference radio because it’s a Jay Allen 2.5-star average performer on MW and my expectations were not high for MW reception on a short whip.  To my surprise that average bar turned out way too low for the Belka!

That was sure asking for a comparison with the most sensitive MW radio I have and gave me hope to use the Belka for ultra-portable MW DXing on the move.  The omnidirectional whip doesn’t allow me to null out unwanted co-channel interference though, therefore I wanted to find a reasonably sized loopstick antenna to pair with the Belka.  Continue reading →

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Bob’s Bespoke “Rack of Radios”

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Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following:

A Rack of Radios

by Bob Colegrove

You simply cannot have enough radios – a principle I learned a long time ago.  The difficulty occurs when it comes to storing them and yet having them at the ready when necessity calls.  Turns out several of my portables fall within a dimensional range that they can be conveniently stored in a rack on the table.

I would like to say I made a project out of this choosing a fine hard wood for construction, carefully routing each divider into a finely milled slot, tastefully finishing the whole thing off with appropriate stain and varnish, and perhaps lining each slot with felt of finest virgin wool.  However, never having been one to let form triumph over function, instead, I found a couple empty cracker boxes of the right dimensions, made a few cuts with a hobby knife, and applied some hot glue.  Whalla!

Wait a minute.  Is that an unused slot at the end?  Hmm!

I love it, Bob!

I mean, you know those cracker boxes just wanted to become a custom radio rack–! I say save the fine wood working to build the shelf upon which you’ll place your bespoke cracker box radio rack. 

Thank you!

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A Review of Two Medium Wave Signal Boosters

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By Jock Elliott, KB2GOM

It was the survey that Thomas, our Maximum Leader, conducted that got me to thinking about this.

The survey revealed that portable radios were used 38.6% of the time by SWLing Post readers as their “daily driver.” I like portable radios, too, and use them frequently. Hold that thought for a moment.

I also like medium wave DXing (content DXing, really, I enjoy tuning around for unusual programs) because, as Gary DeBock once put it: “It’s a target-rich environment.” With that in mind, I was exploring the CCrane website and found a couple of items – the Terk AM Advantage and the Twin Coil Ferrite® AM Antenna Signal Booster that looked like they might help portable radio listeners who want to pull in medium-wave signals better. I asked the CCrane folks if they would like to review both products, and they sent them to me without charge.

Bottom line: they both work for boosting reception of medium-wave signals.

The Terk AM Advantage is a nine-inch tunable loop encased in plastic, and it requires no power supply. Simply place it near your portable receiver and just the dial to the desired frequency, and you could get up to a 20 dB gain in the signal you want to hear. The loop of the Terk AM Advantage inductively couples with the ferrite antenna inside your portable radio, although the unit comes with a direct wire connector that can be used with some radios.

I tried the Terk AM Advantage with my CCrane Skywave SSB on an AM that was coming in with a lot of static at my location. Without the AM Advantage, I had 3 bars of signal strength. As soon as I placed the AM Advantage close to the Skywave and adjusted the tuning knob, the signal strength increase to 5 bars, and the audio was much easier to hear with less noise.

With my Tecsun PL-880, which has a numerical signal strength meter, signal strength was 11 without the AM Advantage, but with the AM Advantage, signal strength increased to 14, and it was much easier to hear. The Terk AM Advantage definitely provides a modest boost in signal strength and clarity, is easy to use, and requires no batteries or external power supply.

The Twin Coil Ferrite® AM Antenna Signal Booster is more complicated. It consists of an antenna element that measures 8.5″ W x 2.5″ H x 1.25″D, a tuner unit that measures 3.25″ W x 4.25″ H x 1.25″ D, a small ferrite stick, and some patch cords. It comes with an AC adaptor and can also be powered by a 9-volt battery. For radios with external antenna connectors, package also includes a RCA female patch cord to two bare wire ends.

Set up is pretty easy: connect the tuner unit to the antenna element with a patch cord; connect the tune to the ferrite stick with another patch, and provide power through either the AC adaptor or 9-volt battery. (I used a battery).

Here are C.Crane’s directions for how to use The Twin Coil Ferrite® AM Antenna Signal Booster with a portable radio:

  • Place the Tuner Control in a comfortable location relative to your radio. Place the Antenna Element a few feet away. If the Antenna Element is placed too close to the radio, it will cause noise on your radio.
  • Place the Ferrite Stick on top of the radio near the center. Placement will vary depending on where the internal AM antenna of the radio is located.
  • For testing purposes, tune your radio to any weak AM station. It is important that the station be weak so you can clearly detect the improvement in reception.
  • Rotate the Fine Tune control, it will click on and the red LED indicator light will come on. Turn the Coarse Tune control knob slowly and you will likely notice a change in reception at some point on the dial. Adjust the control knob until you notice the most improvement on your signal. Now you can use the Fine Tune control for further refinement.
  • Move the Ferrite Stick around the radio to find the position that affects the signal the most. This position is the “sweet spot”, or the best position. Again, adjust the Fine Tune on the Tuner Control for the best reception possible. (I used rubber band to hold the Ferrite Stick in place, but the unit comes with some double-stick foam tape to hold it in place.)
  • Now you can orientate the Antenna Element for best reception. In most cases, the Antenna Element does not have to be adjusted again. When radio noise is a problem, try rotating the Antenna Element in the direction which reduces noise to a minimum.

And The Twin Coil Ferrite® AM Antenna Signal Booster works like crazy! With same station on my CCrane Skywave SSB, it boosted signal strength from 3 bars to full scale. With my Tecsun PL-880, it increased signal strength from 11 to 38.

In my view, although The Twin Coil Ferrite® AM Antenna Signal Booster costs twice as much as the Terk AM Advantage and is more complicated to use, it is more than twice as effective in boosting medium-wave signals.

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Frans add a Decca manual antenna tuner to his urban listening post

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Many thanks to SWLing Post contributor, Frans Goddijn, who writes:

Hi Thomas:

I bought a vintage antenna tuner, one that does not need a power source, very basic just a box with some beautiful coils and nice big variable capacitors and it works for the big magnetic loop antenna here.

I have four GRAHN loop antennas which each have their box with dials to fine tune the signal but the big loop didn’t have that yet.

The tuner works well, filters out some noise but I must say the iCOM radio also managed to select good signal from the loop with its own tuner system and the DSP noise filter at the speaker end of the system further clears up the voice sounds.

Video:

Best regards,

Frans

The internals of manual antenna tuners are simply hypnotizing, aren’t they? You’ve a beautifully-built tuner there that is functional and will outlive us all!

Thank you for sharing!

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