Tag Archives: Guest Posts

Guest Post: Here Come the Lithiums

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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Guest Post: Review of an affordable, compact DAB+ portable radio

Many thanks to SWLing Post contributor, Mangosman, who shares the following review:


DAB+ digital audio/FM receiver and Bluetooth Audio Player with 2.4 inch LCD Display 

by Mangosman

Digital Audio Broadcasting with improved audio compression and error correction is called DAB+. I have had this radio for a few years.

Retail in Australia DAB+/FM radios are generally double the price and more. There has only been one model of DAB+/FM/AM radios which is now no longer trading.

This is a size comparison, the sound is very clear and is surprisingly good on music as well, despite having such a small speaker. Even at maximum volume there is no audible noise or distortion. The stereo program HE AAC compressed and FM and Bluetooth and is available on cabled headphones. Such a small speaker cannot produce much in the way of bass, but it is present on headphones.  Since DAB+ is a pure digital system, there is, full stereo, no noise as the radiated signal deteriorates, until the receiver mutes when error correction fails. The radio has a 400 mm long telescopic antenna.

On FM this receiver will decode Radio Data System data, I have had more sensitive FM reception.

This is the most sensitive DAB+ receiver I have owned. I am also currently also using two BUSH clock radios. I also have used older headphone radios, but push buttons and headphone sockets haven’t been very reliable.

This screen shows a full  colour album cover which can fill the screen and title. Smooth FM is the broadcaster’s name because it is simulcast in some other cities on FM and DAB+. The indicators on this screen are level of battery change, muting, stereo indicator, when decoded and the signal strength. Continue reading

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PSA: Your (new) radio’s filters may be wider than you think

AM bandwidth confusion: IF Filters today vs. yesterday

by 13dka

Whether or not a radio is a joy to listen to, or apt for difficult DX is decided to a large part by the last IF filter stage. Most radios of the past didn’t come with many IF filters to begin with, their quality varied a lot and harsh compromises had to be made in multi-purpose radios. With the advent of digital filtering and inexpensive DSP portables, we got spoiled by a rich choice of selectivity settings that came with an idiosyncrasy I had to wrap my head around first, namely a shift in how some (digital) filters are labeled now.

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RF75A Radio

Raddy RF75A Review – Pocket Radio with Interesting Bells and Whistles

Radioddity Raddy RF75A

By Robert Gulley K4PKM

The RF75A is an interesting little radio which (currently) retails on Amazon for ~$53.00 in the States. It can also be purchased via Radioddity directly for $53–if you use this referral code, you can save $15 off a $65 purchase.

Before we get into specifics, two things are worth mentioning right off:

  1. I was asked if I would be interested in reviewing this radio by our fearless shortwave listening leader, Thomas, and the copy I have was provided to me at no cost by Radioddity directly. (I have no other affiliation with them, but have recently purchased a GMRS mobile radio from them which I am looking forward to using when I finish my review of the RF75A.)
  2. This is, as you will see from the photos I am including, a pocket radio, not to be confused with a tabletop radio or a small portable radio such as the CCRadio Skywave or similar radio. I mention this because invariably there will be folks who expect tabletop or portable quality from a radio about the size of a playing card. It is not going to happen!

Having those thoughts out of the way, the quick and dirty answer as to the quality of the radio is, I am impressed. For those who have not read anything related to my past experience with radios, I have been a shortwave listener since I was about 10 years old, and now in my early sixties. So, I have seen a fair number of radios in my time (speaking as an old codger, or is that curmudgeon?) and have even moved with the times to incorporate SDRs into my radio arsenal.

Each style of radio has its place, and a pocket radio is designed to be the ultimate in portability and space savings. As light as this shirt pocket radio is, it still manages to feel reasonably solid, and of course, it could be packed into anything one was taking along for a trip.

Size Comparison with Playing Card and Cell Phone Battery

The radio measures 2.5″ x 3.5″ x 1″. Playing card and cell phone battery for comparison.

Here are some specs from the manufacturer’s website (saving you my long-winded descriptions!):

  • APP Control SW Radio: Thanks to the app intelligent remote control and Bluetooth 5.0 features, you can enjoy the convenience of RF75A. With its intuitive user interface and powerful wireless capabilities, you can easily control your radio from your devices (support iOS, Android, and HarmonyOS systems).
  • Wider Reception Range: Listen to FM, VHF, AM, SW, and WB, and stay up-to-date with your favorite radio shows and music with this powerful multi-band receiver. RF75A has a wider range of shortwave frequencies compared to the RF750.
  • Automatic Scan and Manual Storage: You can save up to 396 stations, so you can easily access your favorite stations. Experience powerful sound and crystal-clear reception with its 9.85′ wire antenna.
  • Personal Music Player: Boost your music experience with this all-in-one outdoor audio system. With Bluetooth 5.0 feature, a 3.5mm earphone socket, and a TF card socket, you can easily connect to your personal audio devices and connect to your computer as a speaker.
  • Outdoor Companion: This one-of-a-kind radio is designed to be small and lightweight, making it ideal for travel and outdoor activities. Use the flashlight and SOS for emergencies.

What’s in the box?

  • 1 x Raddy RF75A
  • 1 x Storage bag
  • 1 x Lanyard
  • 1 x Wire antenna
  • 1 x Type-C charging cable
  • 1 x Earphone

Reception

I always like to start a radio review by either listening to AM stations first, or WWV time stations for checking out shortwave reception. In this instance I started listening to AM stations in the daytime to see what I could hear on a typical day (no storms nearby, early spring, etc.).

Living in a fairly remote area I was surprised it captured as many stations as it did, making me think the ferrite bar inside must designed well for such a small radio. Evening and nighttime listening brought in many of the usual stations with which we are familiar, particularly the so-called Clear Channel stations. What was more impressive were the many small stations I was able to pick up, not only at night, but early in the morning around 8 a.m.

Ferrite Bar- Front View

Surprisingly effective Ferrite Bar

Ferrite Bar Side view

Side vide showing the magnetic wire wrap

One in particular caught my attention as I am quite certain I have never captured them before, was WHKY 1290, Hickory North Carolina. That’s a distance of about 285 miles, received in the morning. I am only about 50 miles from Cincinnati and cannot receive some of their smaller stations on any radio! Color me impressed!

Nighttime brought stations in from several thousand miles, as you would expect, yet I was likewise impressed with this little radio’s capabilities on AM.

FM

I confess to not being much of an FM listener, but I did tune around the band for FM stations to test its ability to “lock on” to signals (as indicated by a tiny red light) and to pick up stations from quite a good distance away with clarity and good sound.

This might be a good time to mention the quality of sound from the small 3 Watt(!) speaker and bass boost from the back. Again, this is not my Sangean 909 X2 with a large speaker, nor my CC Radio EP, but it has rather amazing clarity and volume capability for such a small radio. I cranked the volume up quite high with no distortion, and even though the speaker is small, the bass boost seems to round out the sound quite nicely, avoiding some of tinny sounding speakers common in such a small radio.

Weather

The radio has coverage of the NOAA weather radio stations and it surprised me with being able to receive 4-5 stations, more than I have gotten with most other radios. All but one of the signals were crystal clear, with the fifth having some noise, but still quite intelligible.

Air Band

This radio includes the air band frequencies and amateur 2-meter frequencies (30.000-199.975 MHZ). I am usually able to receive some signals, but I am quite far away from any local airports or repeaters, so my main reception is from CVG, Greater Cincinnati Airport. While the radio scans the air band frequencies, like any other radio, it is best to find local frequencies you want to hear and program them into memory so you are not wasting a lot of time scanning dead air (these are country specific). Likewise amateur repeaters or GMRS, marine, or public service channels would be best used in memory channels except when scanning for new frequencies.

SWL

Shortwave listening is very respectable, with frequency ranges between 4.750-21.850 MHz (it does not have SSB capability). Tuning can be accomplished by pressing and holding one of the directional tuning keys for about 2 seconds, a long press scans faster. A single press of either directional button will move the frequency increment based on the band/mode chosen.

The radio also features something I have come to really like: a pause button which works not only in music mode, but also when receiving regular radio signals, activated by a quick press of the power button. The frequency is held while pause is active, and then releasing the pause with a second quick press of the power button resumes with all your setting still active.

When comparing this with another radio it was particularly useful instead of having to turn the volume down like most radios. This feature is also nice for answering a call or other interruption, and you resume right where you left off.

Sound Effects, TF Card, Audio in, Bluetooth Usage and other Errata

I have not covered these features as they do not impact radio reception, but I mention them just for completeness. All of these features are available and can be read about in the user’s manual. I will mention the flashlight feature and the emergency siren features, as these are useful for portable operation. The light is quite bright, and the siren will hurt your ears if you trip it accidentally, especially more than once. Ask me how I know!

There is a sleep timer as well as an alarm clock function, with the sleep timer adjustable by default starting at 90 minutes. Most buttons have multiple functions depending on the mode employed, so reading the manual is important for some of these features. I was able to get up and running without reading the manual initially, but some features were functional only in certain modes, so eventually you will need the manual which can be downloaded from the Radioddity site.

The App

A bit of a novelty in this size and type of radio is the Apple/Android app available to control radio functions remotely through Bluetooth connectivity. I have to say, on Android at least, the app is beautiful and I wish more apps used such a clear color scheme and large controls. Your mileage may vary based on your preferences, but I like it!

Phone App on Android

The free Phone app on an Android phone. I like the crisp, clear layout and colors, and the intuitive design.

As to function, the app gives you more information than the radio screen, such as the Bandwidth, SNR, received signal strength and the volume setting in one display. As a side note, the radio can still be adjusted at the radio, and then changes are reflected in the app almost instantaneously.

Of course, the main use for the app is to operate remotely, and the controls are easy to use, including, most importantly, direct keyboard entry of frequencies! This is always the biggest drawback to small radios without a keypad. There are instructions for using the app, but for the most part the app is laid out so well you can control the radio pretty much intuitively.

Negatives –

Yep, there are a few. When tuning with a single press each time there is some soft muting – fortunately it does not last long, but it is there. The buttons also make a clicking sound, not too loud, but it is there. If something like that annoys you, be aware all the buttons make a mechanical click.

I have noticed on several occasions that the band/mode button may stick slightly and take you past where you want to go. Not a big problem, but it does happen now and again. Of course, this could just be my unit.

Also, naturally, the buttons are small. And while I did not have much of an issue even with fairly large fingers, there were times when I pressed the desired button but also hit the one below it. Not a problem for me, but again, if you have very large fingers you may find the radio a bit tricky to navigate in some places. (This only happened on the front buttons for me, the tuning buttons are adequately spaced for most anyone I think.)

The telescoping antenna is probably the weakest point on the radio – similar to most radios, really. It is thin and could be bent easily. I had no difficulties, but I always took care to raise it gently and watched where I was moving the radio around. Then again, I do that will all my radios with telescoping antennas. Just a heads-up to be careful.

Concluding Thoughts

I like this little radio, and will probably keep it in my car for those times when I might want to listen to the radio out and about, check the NOAA weather forecast, use the flashlight, or (hopefully never need) to use the siren. The battery seems to last a long time on a charge when using the radio – I cannot speak to the MP3 drain or a prolonged flashlight/siren drain, but under normal use it seems excellent. It uses a USB-C connection like my phone, so charging is not an issue for me. It will almost fully charge in an hour; the instructions say 2 hours.

Pocket radios certainly have their niche, and I think this one does quite well in that role. If you are in the market for such a radio, I think you will be pleased, especially for the price and the addition of the free remote-control app. 73!

Click here to check out the Raddy RF75A at Radioddity.

Click here to check it out on Amazon.com (affiliate link).

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Guest Post: Listening to LRA 36

Many thanks to SWLing Post contributor, TomL, who shares the following guest post:


Listening to LRA 36

by TomL

I finally had time to go outdoors to listen to LRA 36, Antarctica.  People were gushing about how well it is being received.  My location was a park across the street from the Forest Preserve I usually go to (the Forest Preserves are shutdown and gates locked after sundown).  Even though it was after sunset, this Park has no gate or chain to prevent people from parking there.  In the dark, I setup the trusty amplified Loop-on-Ground antenna, SDR, and laptop.  Solar Flux Index about 179, K index 2.

Started recording and, NOTHING! ARRGH.  But I had just heard it at home in the noise!?!?  Waited about two minutes and all of a sudden music started playing in the middle of a song.  S6 – S7 strength with lots of fading.  Very cool.  20 minutes later, went off the air.  Then 10 minutes later, came back on again in the middle of another song.  They must be tweaking the transmitter.  This feels like the 10 kW transmitter; no way could a 1.5 kW be this loud over 12000 kilometers!  Also, an advantage with IQ recording of a spectrum is I could tune into it later.  Good thing because between their tweaking the transmitter, my SDR, and the crazy propagation, I had to tune to 15475.983 kHz in order to get the USB signal perfectly in pitch.

For your listening enjoyment if you have not had a chance to hear it clearly, I have uploaded both recordings to archive.org where you can listen as long as you want.  Worth listening to, playing music of Argentina music bands.  Happy Listening!  Here is the link to Archive.org and the audio files are also embedded below:

LRA 36 at 00:30 UTC on 05 March 2023:

LRA 36 at 01:00 UTC on 05 March 2023:

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Paolo’s review of the Eton Elite Satellit

Many thanks to SWLing Post contributor, Paolo Viappiani, who shares the following guest post:


ETON Elite Satellit: an expensive flop 

by Paolo Viappiani, Italy 

Introduction 

After various and sometimes conflicting announcements that have created strong expectations in radio listening enthusiasts, ETON has recently launched on the extra-European market (basically in the United States) what should have been its “top of the range” portable, the Elite Satellit model . Aesthetically (and also functionally) inspired by the previous E1 model, the new portable radio should have been free from the defects of its predecessor, in particular as regards the “sticky” coating of the plastic case but also with respect to other technical drawbacks repeatedly reported by users (display contrast and shading, etc.).

The new Elite Satellit was announced to look practically identical to the E1 model and to use the same cabinet, but with various additions and improvements: RDS, FM-HD reception, Air Band, etc. A frequency resolution of 10 Hz in the shortwave bands, a PBT (Pass-Band Tuning) facility, a large LCD display with the possibility of changing its background color were also provided.

It is therefore obvious that its release was highly anticipated, and the resulting expectation gave rise to numerous pre-orders of the radio in the United States, where the main distributor was (and still is) the well-known Universal Radio company owned by Fred Osterman [1].

Unfortunately, the initial boom in sales of the ETON Elite Satellit was followed by many return requests due to the poor performances of the radio and the numerous defects encountered by users, also reported in a lot of videos and negative reviews on the Internet [2].

Fred Osterman himself, disappointed by the performance of a radio that he should have sold as an excellent portable, began to test the individual devices in his own laboratory and to return to ETON all the units that did not meet the declared specs (basically the vast majority of those received for sale) [3]. All this caused great confusion at ETON, which was forced to somehow remedy its errors (mainly due both to a very approximate alignment of the circuits and to an almost non-existent final quality control).

Unfortunately, despite the precautions adopted “hastily” by ETON, most of the “overhauled” devices that were returned to Universal Radio continued not to comply with the specifications, so that Fred Osterman, who is a good technician and a very honest dealer, decided to cancel most of the orders received and to sell the very few radios found to be in good working order within the United States only, (see again note [3]). I myself placed an order from Universal Radio for an ETON Elite Satellit on August 8, 2022 (Order ID: #8992932, retail price $599.99 plus shipping and import customs duties), but Fred was forced to “drastically cut” the orders received and to cancel mine too, due to the impossibility of satisfying the many customers on this side of the pond. However, my desire to have an example of the ETON Elite Satellit in my hands, in order to be able to see, test and judge the new radio it was really great, and great was also the wish to realize if the many negative impressions circulating on the web were or were not justified and true.

So I decided to look for other ways to buy the “latest cry” of ETON. The opportunity presented itself to me, almost unexpectedly, by visiting the American site of Amazon [4].

The purchase and the arrival of the radio; my first impressions 

I therefore ordered an ETON Elite Satellit portable radio on the Amazon.com website on January 17, 2023 at the price of $698.16 (including shipping and customs duties). I report in Figure 1 the screenshot concerning my order #113-3575479-2262609 which, as it appears, was delivered to me on January 23, 2023, after only five days; this demonstrates the truthfulness of my statements.

Figure 1: A Screenshot of my Amazon.com order dated January 17, 2023.

The shipment was delivered to me by UPS courier in the usual Amazon packaging in a plastic bag (Figure 2).

Figure 2: The UPS label and the Amazon plastic bag.

Inside the envelope was a cardboard box containing the radio, in understandably less than perfect conditions (Figure 3).

Figure 3: The cardboard box of the ETON Elite Satellit.

Figure 4: The contents of the radio box.

Once the package was opened, the contents of the box looked like in Figure 4: two shock-absorbing spacers held the device in position (inserted in a plastic bag) and its AC power supply (into a white box, and obviously with a 117V input voltage). There was also the “User Guide” in a paper version and a “mini-guide” to listening to short waves; completely absent was the CD that used to be enclosed in the box of the previous E1 version of the radio.

Continuing with the operations, I came across a sort of brown plastic cover intended for the protection of three sides of the radio (front, top and back) which can be held in position by some magnets and is provided with two circular holes in correspondence with the tuning knobs and volume of the radio (Figure 5).

Figure 5: The ETON Elite Satellit radio and its “case” (?)

I omit to make comments on this “protection”; I only say that in my opinion it is useless (and ugly too) and I believe that the gentlemen of ETON could have wasted their energies otherwise; but maybe someone likes it too…

Figures 6 and 7 show the front and back of the portable radio as soon as it has been removed from the protective plastic bag. Note the almost identical appearance of the cases of the Elite Satellit and of the previous E1 model.

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Loop-On-Ground Antenna Part 3: Tom’s low-noise, low-profile, portable antenna evolves

Loop on Ground Antenna Part 3

(using multiconductor wire)

by TomL

It dawned on me recently, perhaps due to sloppy thinking or unintended distractions, that I never wrote about my modified Loop on Ground (LoG) receive antenna that I use at parks and such.  For over a year now, I have been using 3-conductor rotor wire bought cheap at the local hardware store and have wired the conductors in series.  Grayhat (Andrew) was the inspiration when he decided to create a folded dipole along the side of his house.

The usual construction of a LoG antenna for shortwave is a single wire of about 60 feet in circumference in order to not go above one wavelength for 20 meter band usage.  If you recall, going above one wavelength will start creating weird lobes in the reception pattern.  See – Loop-On-Ground Antenna Part 2.

However, I did not like this 19 foot diameter wire on the ground in public parks just waiting to be tripped over.  Like, the time when a horse got loose from its owners and almost tripped over my 60 foot wire.  I don’t think I would have liked the resulting lawsuit!

So out of fearful necessity I took some leftover RCA 3-conductor rotor wire, about 29 feet of it, and wired a loop with the conductors in series.  This gives about 81 feet of total conductive length.  But since it is folded onto itself, there is an undetermined loss of resonant length.  Callum (M0MCX) of DXCommander fame has experimented and found folded dipoles need three times more length in the folded section to reach resonance, so my loop is probably around 69 feet (electrically).  See – Fold the end of a Dipole Back – What’s Happening?.

In the picture below, the black wire with Ring Terminal at the bottom goes all the way around to the other side, soldered to the green wire, which goes around and is soldered to the red wire, which goes around to the Ring Terminal at the top, plus tie-wraps to hold the wires together.

The next picture is how the Wellbrook Medium Aperture preamplifier is connected to the loop with BNC cable that goes to the 12V power injector.  I have had this Wellbrook unit for maybe 6+years with no signs of problems.  WARNING – do NOT use the Wellbrook preamplifier in the presence of high powered RF energy like your Amateur Radio antenna pumped with 1000 watts from a  linear amplifier; the Wellbrook premap might just overload and get damaged!  I did use this loop and preamplifier at last year’s 2022 ARRL Field Day and was able to get away with it because we were only using 100 watts per station.  Listening to the 9pm 3916-net trivia group was fun but I still needed to keep it away from the transmitting antennas. Continue reading

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