Category Archives: AM

DSP noise may come from clock and data line harmonics

In response to our review of the Sangean ATS-405–which noted DSP noises on 800 and 1600 kHz–SWLing Post reader, Steve Yothment, comments:

“Yes, modern radios usually have a micro communicating with the DSP IC through I2C communications.

The inter-IC communications includes a clock and data line. The clock for I2C is typically 400 kHz nowadays. Harmonics from this clock line are probably the source of the interference.

The manufacturer should have designed the product to ensure that this interference does not occur. It may be that they resolved it at one time but with limited manufacturing quality and component substitutions that often occur in mass production, the problem is occurring now even though it may have looked OK earlier in development. At least, that is my experience with such things. (I used to design car radios for the Panasonic Company.)

You can learn more about the I2C bus at https://en.wikipedia.org/wiki/I%C2%B2C.

Many thanks for your comments, Steve! I recall a similar metronomic sound on another DSP-based radio, but can’t remember which model. I need to dig through my reviews as I’m sure I noted this. I believe checking 400, 800 and 1600 kHz will become a standard checklist item when I review DSP-based radios.

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The Aiwa FR-C33 AM\FM\WX portable radio

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A few weeks ago, SWLing Post contributor, Ron, sent me an eBay listing for a radio with which I was not familiar: the Aiwa FR-C33.

Ron wrote:

“I know you are primarily HF but here is something rather special and unique and inexpensive:

Aiwa’s response to C-Quam in the late 90’s was “AM Wide.” Apparently all this meant was a somewhat wider Murita ceramic filter.

But…the bandwidth just matches the 10,200 cycle limit imposed on AM stations today…try a Sony SRF-42 or SRF-A1 C-Quam receiver at night on today’s band and note that they’re just too wide.

I have one of these and can tell you the build quality is great…it has a tone control and on Sony Walkman headphones stations like WSM are just flat-out unreal in sonic quality…the speaker isn’t bad, either.

A nice big ferrite bar makes it a bit of a DX machine, too.

FM is also very good; even the weather-band add-on works too.

Very much worth a go for your collection and enjoyment[.]”

Aiwa-FR-C33-Back I’ve been enjoying the FR-C33 for a few weeks now; Ron’s assessment is spot-on.

The FR-C33 produces clear audio via its internal speaker, but where it really shines is with a pair of good headphones plugged in. Though it has no “Mega Bass” feature like many radios of its era, the Aiwa produces great bass tones via a good set of “cans” (I’ve been using my Sennheiser HD 428s).

The FR-C33 has a very useful tone control with a smooth, wide spread between the full bass and treble settings.

All of the FR-C33’s controls are fluid and functional.

AM (mediumwave) reception is truly fantastic. I find that the analog tuning wheel is easy to use and there’s enough room for the needle to easily travel across the dial without skipping stations inadvertently (a problem I often find with smaller analog portables).

It really shines, however, when you can center on a local broadcaster with a quality AM signal. While the FR-C33W doesn’t receive C Quam stereo, of course, its wide AM filter offers up excellent fidelity.

FM reception is also sound. While I haven’t done a formal comparison on FM, it receives my benchmark FM stations with ease and produces great audio fidelity via headphones. Sensitivity-wise, it might lag slightly behind some of the better DSP-based radios out there, but for an inexpensive analog receiver, it must be at the lead of the pack.

Ron, I really appreciate the recommendation–thank you! The FR-C33 is a keeper for sure.

Though these don’t pop up regularily on eBay, you can search for an Aiwa FR-C33 by clicking this link.

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Winner of the Virtual Radio Challenge III

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Dennis Blanchard (K1YPP), author of Three Hundred Zeroes: Lessons of the Heart on the Appalachian Trail, recently contacted me from the road, en route to another lengthy trail in Vermont.

Before this latest hiking expedition, Dennis spent many hours pouring over the Virtual Radio Challenge III entries, looking up weights and specifications of radio gear and accessories…And the upshot? He’s chosen a winner of our Reader Challenge.

Again, in summary, a participant’s goal was to find the best and most portable radio gear to receive shortwave, AM (medium wave), FM, and NOAA weather to support a long through-hike on the Appalachian Trail, to plan each day’s hike, and to make accommodations for frequent spring and summer thunderstorms (as well as occasional spring snow or sleet)…all for a budget of $300 US. [Read full details of the Challenge by clicking here.]

This year, Universal Radio rewarded–and has already dispatched!–a brand new CountyComm GP5/SSB portable receiver to the winning entrant.

Below are Dennis’ comments, along with those of the Challenge winner.

Dennis Blanchard (K1YPP) writes:

“This photo was taken in NJ. Shortly after I took these photos, and walked down the trail about a 100 feet, a bear came over to check the table to see if I had left anything.” (Photo: K1YPP)

Dennis Blanchard operating a portable radio on the Appalachian Trail. (Photo: K1YPP)

I’ve just spent about five hours going over the entries. There are several that are very good…indeed, Challenge participants obviously put lots of thought into their entries.

It was really tough to decide, but I had to go with most practical.

Weight is a big consideration for me, and that leaves out solar panels, hand crank generators, and the like.

What most don’t realize is that the AT has a nickname: “The Long Green Tunnel.” This eliminates solar panels because there is little sun to be had, as you’re in the shade most of the time. By the time you get to camp it is usually too late in the day for any charging, and wearing a panel just doesn’t do any good because of the shade (and weight).

Not only is weight an issue, so is space in the pack…hikers need all the room they can get for food, and in the cooler weather, heavy clothes.

Anyway, out of five finalists, I would have to go with Eric McFadden (WD8RIF).

Eric’s winning entry

So, what did Eric choose? The following is Eric’s winning entry, beginning with his radio choice and following with a clear, practical explanation for it:

C.Crane CC Skywave, AM/FM/SW/Air/WX, $89.95 at Universal Radio

Sangean ANT-60 Roll-Up 23′ Antenna, $12.95 at Universal Radio

Energizer L91 Ultimate Lithium Cells, AA, 12-pack, $17.45 at Amazon

“The C.Crane Skywave is small (4.75″ x 3″ x 1.1″); light (5.5oz); power-stingy (30mA with headphones); and receives AM, FM, SW, NOAA Weather, and VHF Aviation.The Skywave runs on two AA cells, and comes with a case and CC Earbuds.

The Energizer L91 Ultimate Lithium AA cells provide 1.5v at approximately 3000m Ah, weigh 1/3 that of an alkaline AA cell, and last several times longer than an alkaline cell.

The Sangean ANT-60 would be tossed over a handy tree-limb and clipped to the Skywave’s whip antenna when the Skywave’s built-in 16″ whip isn’t quite adequate for listening to a shortwave broadcast station.

The purchase price of the Skywave, six pairs of Ultimate Lithium AA cells, and ANT-60 would be about $121 plus shipping, well under the $300 limit. The entire station should be small enough and light enough for easy carry in a backpack. If the twelve Ultimate Lithium AA cells don’t last the entire hike, enough of the budgeted $300 remains to purchase more cells (either Ultimate Lithium or alkaline, as available) along the route.”

To this sensible explanation, Eric adds:

“Being a ham radio operator, I’d want to have a ham rig along, too. While I’d love to be able to operate HF CW along the AT, my Elecraft KX3 is too large and heavy to carry that far. However, my current Yaesu FT-60R 2m/70cm HT and Diamond SRH77CA whip should travel nicely clipped to a backpack strap and would serve as a back-up receiver for NOAA Weather and be available for pedestrian-mobile QSOs (chats) and calls for help, if needed.

In order to save weight and not have to hassle with charging batteries, I’d leave the NiMH pack at home and carry the FBA-25 six-cell AA holder and stuff it with additional Energizer Ultimate Lithium cells in order to save weight.

Since the C.Crane Skywave already meets all the requirements of the Virtual Challenge, and since I already own the HT, battery holder, and antenna, I won’t consider the cost of the HT, antenna, and batteries as part of the challenge.”

About Eric’s entry, Dennis notes:

Eric’s solution is small, lightweight, and does everything needed. He speculates that he would also bring along his Yaesu FT-60R, but didn’t feel he could include it because of cost. Curious, I looked it up on Amazon; should he take it along, this addition would still keep his total well under the $300.00 limit.

This would provide Eric with two receivers, [the ability to enjoy] ham radio communications, and not much weight to haul. He includes the AA Lithiums, and I have to say that, without a doubt, these are the finest hiking batteries out there: they’re light, last forever, and are readily obtainable. I only had to change mine out once on the entire, six-month AT hike, and I was on the air a lot.

Several of the other entries were winners also great; I basically had to use a dartboard to pick a winner. Good thinkers out there, especially considering none of them have actually ever done a hike of this magnitude.

Congrats, Eric! Thanks, Dennis! And more to come…

Congratulations to Eric McFadden for such a well thought-through entry!

I must say, I don’t envy Dennis in making this selection: it was obviously a challenging process on his end, too, and I’m glad I didn’t have to make it!

Dennis informed me that he plans to post and comment on some of his favorite entries in a few weeks, once he completes this latest multi-week hike. We will, of course, post his comments along with the finalist entries.

Note that when I originally received the reader inquiry which prompted the idea behind this Reader Challenge, the CC Skywave had not yet entered the market. Yet several of you chose it as your sidekick for the Appalachian Trail; clearly, clever minds think alike. Obviously, a radio that would function well on the Appalachian Trail would also be a great radio for your BOB (“bug out bag”), go kit or emergency supplies.

Thanks again to Dennis Blanchard, our intrepid judge, thanks to Universal Radio for the great prize, and many, many thanks to all our Reader Challenge participants, who made this process even more exciting and challenging! Meanwhile, don’t worry if you didn’t win the CountyComm GP5/SSB this time; we’ll soon have another opportunity to win one of these handy rigs in a completely different–and fun!–way.

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Obtaining QSLs from AM broadcast stations?

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SWLing Post reader, Paul Grodkowski, writes:

“Just a quick question to anyone at the SWLing Post:

Is the practice of sending a reception report to a AM broadcast station in return for a QSL card still accepted in the age of the internet ?

So many stations are broadcasting online now that I wonder if they have QSL cards at all?

I just want to keep up with the times and not bother busy people at radio stations and look out of date, yet at the same time would like to confirm report of reception.

Any information would be greatly appreciated.”

Thanks for your question, Paul! I’m no expert on AM broadcast QSLing, but I’m pretty sure many mediumwave stations still respond to listener reports. Indeed, I believe there are even radio enthusiasts who act as QSL managers of larger clear channel stations (CFZM comes to mind).

Of course, one brilliant resource for all things MW DX is the National Radio Club (NRC).

Readers: Can you help answer Paul’s question? Please comment. Also, if you have some AM broadcast QSL cards, please contact me as I would love to post some.

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Update: Sangean ATS-405 review

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After publishing my initial review of the Sangean ATS-405 on July 25, I contacted Sangean and requested a sample radio for comparison purposes. Back story: there were some receiver performance issues that I suspected may have been tied to my particular ATS-405 unit. Sangean kindly dispatched another ATS-405 which I received last week. The following is an update to my initial ATS-405 review.

In truth, there were two main reasons I wanted another unit to compare to my initial review radio:

I wanted to see if the new unit showed improved performance–sensitivity, selectivity, and, specifically, noise floor–in comparison with the first review unit tested
I noted strong DSP “birdies” (noises) on 800 and 1600 kHz on the test model, while several of our readers commented that their ‘405s did not feature birdies

Shortwave sensitivity/selectivity and noise

I noted in my initial review that the initial ATS-405 had an ever-present noise, a sort of low-volume static hiss. The noise floor, while not high, certainly seemed to be higher than other comparable shortwave portables, and was most noticeable when tuned to marginal/weak stations. I suspect many listeners may not notice it unless they compare it with other portables.

Fortunately, my new review unit’s noise floor seems to be slightly lower than that of my initial review unit. [Perhaps this unit’s board is better soldered–?] The noise is still there, but can be better mitigated by judiciously using narrow filters and the three-position audio tone control.

I suspect this is a noise somewhere in the audio amplification chain, because I find it less noticeable with headphones, and more pronounced via the ATS-405’s internal speaker.

In terms of sensitivity and selectivity on the shortwave bands, I believe my new unit is identical to that of the initial review unit. That is to say, the ATS-405 is not an especially sensitive shortwave receiver, but fairly average, and thus will fit the bill for most but not for the discriminating weak-signal hunter. Frankly, even my $46 Tecsun PL-310ET does a better job of pulling in weak stations.

I’ve tried tinkering with the AGC settings and soft mute–very cool features!–in an attempt to improve sensitivity, but alas, these only help the quality and stability of the received signal.

Birdies

Immediately after opening the box of the new ATS-405 sample, I popped in a fresh set of AA batteries and tuned the Sangean to 1600 kHz AM. [If you read my initial review, I noted a strong DSP birdie on 1600 and (to a lesser degree) on 800 kHz].

At first listen, I was happy to note that the new unit lacks the wild DSP noise that overwhelmed my favorite local station on 1600 kHz.

As I listened more carefully, though, I did note a metronomic “chick” sound that was also present but partially buried in the noise on my initial ATS-405.

Below, I’ve embedded audio comparing the two receivers:

Initial review unit:

New review unit:

Listening to these samples, I realize I may have had the filter set to the middle position on the first sample and the wide setting on the second (hence, the brighter tone).

To further demonstrate the difference between the two, I made this short video; I start with my initial review unit, then switch to the new review unit provided by Sangean:

Note that this was recorded at least 100 feet from my house on the tailgate of my pickup truck. DSP birdies on 800 kHz sounded very much like the 1600 kHz sample, save the noise level on the latter is slightly lower and there are no broadcast stations in the background.

None of my other portables have digital noises or birdies on 800 and 1600 kHz.

So, the bad news: I do still hear a noticeable (and slightly annoying) internally-generated noise on the new review unit. The good news: it isn’t as objectionable as that on my initial review unit.

Summary

In short: I stand by my initial review of the Sangean ATS-405.

While the new ‘405 review sample seems to perform better than the initial ‘405 sample, I find the discrepancy somewhat marginal, especially since I spend the bulk of my time on the shortwave and mediumwave bands.

I’m not a fan of production runs where units vary so greatly from one to another, making accurate testing difficult. Therefore it’s quite possible you might receive a unit that performs better than those I tested…but unfortunately, the opposite is also true.

So, if you’re a Sangean fan, if you don’t mind the birdies on mediumwave, and if you mostly listen to strong shortwave stations, you may entertain purchasing an ATS-405. The keypad layout is almost identical to previous Sangean models.

To be clear, of course, this radio’s negatives above have been viewed under a microscope; the ATS-405 is not a “bad” receiver, it’s just not that exceptional. Other than the added mute/AGC/squelch features, when compared to its predecessors, it’s really not a better iteration.

In conclusion? For the $90 US price, I believe there are better receivers out there–such as the Tecsun PL-600 (which, as a bonus, has USB/LSB reception–and saves you $10, to boot).

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Radio Caroline and a crystal radio: “The making of a rebel”

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Radio Caroline circa 1960’s.

Many thanks to SWLing Post reader Mike, who shares a link to this story from the blog
République No.6:

Growing up in Piennes Lorraine, Radio Caroline the making of a rebel

[A]t night with my younger brother we would listen to a “pirate radio station” on a boat that would put real good music on, crusing the international waters between England and France. He burst in laughter and told me: That’s Radio Caroline“. That was it. My brother and I would listen to that station nearly every night on an old “galena radio receiver” with a huge antenna hidden in the attic built with copper wire we stole at the mine. I mean we didn’t really steal it, it was everywhere. It was the wires used by miners to connect detonators to batteries when blowing new tunnels and locals were using it for all sorts of things, like holding parts in chicken coop to tie tomato or green bean plants to stakes and could be found everywhere.

Actually at first we set the antenna in our bedroom but somehow it wasn’t long enough not to mention mom who saw it and tore it down giving her an other excuse to punish us. So we decide it to place it in the attic where no one ever went.

The most difficult part was going to the attic, there wasn’t any stairs. We had to bring a ladder to the trap leading to it. Mom was watching us like a hawk, looking for any excuses to punish us.[…]

Read the full story at République No.6.

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Tuning in to AM broadcast history and the venerable RF-2200

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Many thanks to SWLing Post contributor, Eric (WD8RIF), for sharing a link to this excellent article in the Illinois Times by James Krohe Jr. Here’s an excerpt:

Tuning in: Making a small world bigger and the big one smaller

So much of happiness, I’ve realized, depends on getting tuned in. When he was a young married, my father used to tune in the console radio in the living room of the Krohe family mansion on Manor Avenue to the live broadcasts of big-band music “from the beautiful Blue Room in the Roosevelt Hotel” in downtown New Orleans. He was able to be in two places at once thanks to WWL-AM, whose 50,000-watt clear channel signal was beamed north. For all I know, while he tapped his toe on the sofa in Springfield, Inuit couples were jitterbugging on the tundra.

For Springfield teens in the 1950s and ’60s, getting a chance to listen to what kids in bigger cities had already decided they liked was important. WCVS-AM was just crawling out of its cocoon, having crawled into it as a country station and emerging as a rock station – although in the late ’50s there wasn’t that much difference. “Rock ’n’ roll” was, in stations like WVCS that catered to mostly white markets, rockabilly and pop-ish country ballads. (Geezers will recall when Brenda Lee was, briefly and laughably, marketed as a rock artist.)

For Top 40 music, as for so many other things, if you wanted to get the really good stuff you had to go to the big city. Around here that meant WLS-AM, WCFL-AM out of Chicago (whose Ron Britain made Soupy Sales look, or rather sound, like Noel Coward), and KXOK-AM out of St. Louis. George Lucas’s American Graffiti brilliantly captured the ways that car radios, transistors, radio stations blaring over PAs in drive-ins, permeated the bubble in which teenagers then lived.

Later I learned I could hear WBZ out of Boston if I acted as the antenna on my transistor. (“Turn on, tune in, drop out” to me meant losing the signal when I lighted a smoke.) WBZ was one of the first stations with the newest 45s from Britain, which allowed us yokels to hear The Yardbirds while the records were still on their way to Midwest stations by stagecoach from Boston harbor.

Continue reading…

Krohe also mentions the virtues of the Panasonic RF-2200 which is, in my opinion, one of the best AM broadcast portable receivers ever.

Click here to read the full article at the Illinois Times website.

Side note: The Panasonic RF-2200 still has a loyal following among mediumwave DXers of the world. The RF-2200 can be found on sites like eBay (click here to search), but make sure you’re purchasing from a reputable seller and not over-paying.

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