Category Archives: How To

Android tablet SDRs?

SWLing Post reader, Philip, writes with the following question:

“I want to know if you are aware of any good shortwave receivers that can be used on an Android tablet.”

I am aware of the Android SDR application, SDR Touch (see image above), but have never used it so I can’t comment on compatibility with the various SDRs on the market. I know that SDR Touch is compatible with devices that support USB host mode–but you may need to do research to see if your Android device and potential receiver are compatible. I believe most SDR Touch users connect their device to RTL-SDR dongles.

Readers: Please comment if you have any suggestions for Philip. I’m also curious if anyone has had success pairing an Android tablet to an HF-capable SDR.

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Primary, Ion, and Polymer: a lithium battery primer

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Energizer ultimate lithium cells are designed to be a lighter, longer-life direct replacement for the AA alkaline battery.

Lithium primary, lithium ion, lithium polymer…want to know the differences between–and varied uses for–these diverse types of lithium batteries? You’re not alone…so did I.

Recently, a reader asked about the suitability of using AA Lithium batteries in a Tecsun radio. Several knowledgeable Post contributors–including Richard Langley, Ken Hansen, DL4NO, Eric Cottrell, and Mark Piaskiewicz–responded, and a discussion of the differences in various lithium cells and their chemistry followed.

I was quite intrigued by this discussion, and wanted to learn more; a bit of research ensued. The wonderful folks at Zbattery.com came to my aid, clarifying the compositions of these various batteries and enlightening me regarding their unique applications.

Following is a (nutshell) primer describing what I’ve recently gleaned from these experts on the subject of lithium batteries. First, a brief disclaimer: the scope of this article is modest, explaining briefly the roles and compositions of the most common lithium batteries used by consumers and hobbyists/enthusiasts. So, if you’d like an even more detailed discussion of batteries, please check out the Battery University website.

With that said, there are generally three types of lithium cells:

1. Primary Lithium (non-rechargeable)

Though this SAFT battery looks like a typical AA, it produces a whopping 3.6V and will certainly fry a radio that is expecting 1.5 volts from each AA cell.

Though this SAFT battery looks like a typical 1.5 V AA, it produces 3.6V and will fry most radios.

Primary Lithium batteries are single-use and should not be recharged under any circumstances. These batteries have a high charge density (i.e., a long life), and as a result, cost more per unit than other single-use (disposable) batteries, such as alkalines.

Primary lithium cells generally produce 3.6 to 3.7 volts; however, there are manufacturers (Energizer and Duracell, to name two) who have developed cell chemistry that lowers this voltage down to 1.5 volts per cell, thus creating a safe, direct replacement for the common AA alkaline battery.

Unless you are purchasing a battery with a AA form factor from Energizer or Duracell, you should double check the voltage of the battery you are purchasing. There are many manufacturers who produce a 3.6 volt primary lithium batteries that have the same dimensions, or form factor, of an AA battery (see photo right), but are used in specialty medical, military, industrial and testing applications in which voltage requirements are higher. These cannot be used interchangeably with conventional AAs, as they will cause harm to a device.

In other words, do your research when purchasing a primary lithium cell! Make sure the voltage matches what your electronic device requires–or as Post contributor, Richard Langley, puts it–“Caveat emptor!” (Buyer, beware!)

2. Lithium Ion (rechargeable)

Lithium Ion batteries are currently one of the most popular rechargeable batteries for consumer electronics on the battery market. There are a number of Lithium Ion variations with their own unique chemistries–and their own unique characteristics–but in general these have a high energy density, a modest memory effect, and exhibit only a gradual loss of charge when not in use.

Generally speaking, Li-ion batteries are not available in voltages most radios and other electronics would need, from, say, AA, AAA, C, D, and 9V alkaline. There are manufacturers who produce Li-ion varieties in a AA form factor (they look like AAs), but which produce more than double (3.6V) the peak voltage of an alkaline AA (1.5V); thus, these lithium batteries, too, can only be used in devices designed around these higher voltages–such as specialty flashlights, military, industrial, and medical equipment.

There are a number of radio manufacturers using slim Li-ion battery packs like the one in the image above.

3. Lithium Polymer (rechargeable)

Most LiPo batteries come in a “pouch” format, designed for specific applications,

Lithium Polymer (LiPo, LIP, Li-poly) are rechargeable battery packs that generally produce 3.6 – 3.8 volts when charged. LiPo packs have much of the same charge and discharge characteristics of Li-ion batteries, however, they are lighter in weight and can be designed to fit almost any shape.

LiPo batteries have a very strong following in the world of radio-controlled aircraft and cars–their feather-light weight as well as gradual discharge curve render LiPos almost ideal for these applications. LiPo packs are also used in consumer electronic, solar, and GPS applications, to name a few. LiPo pack variations are currently being considered for use in electric and hybrid vehicles.

Summary

And so, returning to our original post questioning the use of Lithium cells in reader Philip Dickinson’s Tecsun PL-606, the Tecsun representative was absolutely correct: these batteries, it turns out, are not suited for this application, as the voltage is too high for safe use in this Tecsun.

Since I didn’t have a link to the batteries Philip purchased, I assumed Philip might be referring to Energizer Ultimate Lithium AA batteries, which are direct 1.5V replacements for alkaline AA batteries (and why I use an Energizer graphic in the post).

At any rate, it appears that Philip purchased 3.6V primary lithium cells in a AA cylindrical form factor. If he does pop these AA lithiums in his PL-606, it will surely fry the radio as the voltage is more than double what this radio actually requires.

Hopefully, Philip can return these lithium cells and replace them with the Energizer or Duracell 1.5 V AA variety.

Philip, thanks for writing in with this question; learning about lithiums has been most interesting! And hopefully, this primer you’ve invoked will save other radios from harm: readers, do check your voltage requirements before you insert those lithiums.

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Jeff finds a solution for sticky preset buttons on the CC-Radio 2E

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Jeff, over at the Herculodge blog, recently posted that the preset #2 button on his C.Crane CC-Radio 2E had become so sticky, it was almost to the point of not being functional.

One of his readers suggested that he use Deoxit spray to remedy the sticky button and it worked!

Deoxit is amazing stuff and something I suggest any radio enthusiast keep handy. Years ago, I had an Icom IC-735 I thought needed a new power button;I had to press and hold the button for the power to turn on. I searched for a replacement botton for weeks. When I reached out to a friend who is an electronics technician, he suggested that I open the chassis and try spraying the button with Deoxit.

I did, and it worked beautifully.

Deoxit is not the cheapest contact cleaner around, but it is the brand I trust the most. It comes in both a spray and liquid form.

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Hamfest find: Griffin Technology PowerMate Controller

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A few weeks ago, I attended the WCARS hamfest in near Waynesville, North Carolina. I walked out of that hamfest carrying way more goods than I had intended to purchase (more on that in a future post–!).

One of the best bargains I found was a Griffin Technology NA16029 PowerMate USB Multimedia Controller. The seller is a friend; he was trying (and succeeding) to push off a lot of his gear on me. We were actually in reverse price negotiations at one point–as he kept discounting prices, I was trying to raise them.

Knowing I’m an avid SDR guy, he insisted I give this Griffin Powermate controller a go. I purchased it for $5 after I believe he had offered it for free (yes, the results of reverse negotiations).

I took the controller home assuming it would be cumbersome to interface with my SDRs–what a poor assumption I had made! It was a breeze: simply install the driver, and launch its associated application. The software makes it very easy to associate PowerMate controller actions with keystrokes and other PC functions.

There are a surprising amount of functions this simple knob performs:

Rotate clockwise and counter clockwise
Press down and rotate clockwise and counter clockwise
Press down once
Press down and hold

I set up the PowerMate to control my WinRadio Excalibur as follows:

Press and hold launches the WinRadio Excalibur application
Rotating the knob tunes up and down
Pressing down and rotating increases and decreases bandwidth
Pressing once toggles the volume mute

The PowerMate is a brilliant piece of kit!

It has enhanced my user experience with the Excalibur. Soon, I’ll set it up to work with my Elad FDM-S2, and SDRplay RSP.

The PowerMate software allows you to set up multiple configurations, so it’s easy to call up a configuration based on the SDR being used (since mine have unique hotkeys).

The good news is a new PowerMate is only about $32 via Amazon.com.

I’m quite tempted, in fact, to buy a second unit to use with my laptop and to serve as a spare.

While looking up PowerMate pricing, I noticed more complex multimedia controllers on Amazon; I’m curious if any Post readers have experience with other models.

Seems to be a very affordable way to enhance your SDR user experience.

Click here to view the PowerMate on Amazon: http://amzn.to/1MmyxkC

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A repair story: Vlado’s fix for the classic Sony ICF-SW100

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In June, I made a small leap of faith and purchased a (dead) Sony ICF-SW100 from Universal Radio (see the listing on right).

ICF-SW100-Used-NonWorking You see, for many years, I’ve dreamed about owning this wee little receiver, now a classic among tiny radios, but used ones are typically too expensive for my modest budget.

This time, seeing the ad at Universal, I spoke with Universal Radio directly to obtain more details about their defunct unit; while they simply didn’t know what was wrong with the Sony, they were able to very accurately describe its cosmetic and functional condition…I took a deep breath, and decided to take a chance on it anyhow.

In full disclosure, I have a secret weapon in my camp: my talented friend, Vlado (N3CZ), who is not only the most adept electronics engineer/technician I’ve ever known, but one who truly welcomes a challenge. The thought had occurred to me as I admired the wounded Sony, Wonder if Vlad would like to take this on–?

The answer, of course, was Yes! So I dropped the DOA Sony off at Vlad’s home last week. He disassembled the radio, only to discover that my ICF-SW100 was a victim of the (dreaded) damaged ribbon cable.

A short history of the Sony ICF-SW100 and SW100S

These radios are indeed brilliant, incredible performers for their miniscule size. Yet the first generation of ICF-SW100 radios–those produced before the fall of 1997–have a design weakness: the ribbon cables which connect the upper and lower portions of the radio’s clamshell design eventually fail. Multiple openings and closings bend and cut the cables, rendering the otherwise remarkable little radio useless.

SWLing Post contributor, Dan Robinson, recently shared his knowledge about the ICF-SW100 series. Dan notes:

SW-100 Seekers Beware

As shortwave veterans know, the classic SONY miniportables — SW-1, SW-100(S) and SW-07, represented some amazing technological achievements. SONY managed to shrink some fantastic technology into these receivers, including (with the last two in the line) — SYNC capability. The SW-07, which was the last of these receivers, still brings some high prices on Ebay.

But if you are searching for the ICF-SW-100S there are some things to consider and beware of. As everyone knows, the SW-100 suffered from the well-known ribbon-cable failure problem. SONY addressed this problem in later serial numbers, and changed the design of the radio case.

Modified SW-100s have a notch where the top cover meets the base.

There are some dishonest sellers out there who are trying to pass off older version SW-100s as modified ones. Usually, the tip-off is that the photograph in the Ebay auction will be dark or out of focus, so it’s hard to tell if the radio is the modified version or not.

It has become quite rare to find an original SONY modification kit, which includes a new top cabinet of the SW-100. And some sellers are trying to get as much as $300 for these, though they rarely sell at this level.

This repair kit was on eBay at time of posting.

ICF-SW100 modification kit found on eBay at time of posting.

It’s also becoming rare to see SW-100S radios new-in-box. I had two of these, sold one and kept the other.

If you’re after one of these marvel radios, do what everyone should do when considering items on Ebay — ask many questions about [the] cosmetic condition, accessories, serial numbers, etc.

Universal Radio, a trustworthy seller I know, had fully disclosed the model number and problems with this radio, so I knew exactly what I was buying. Dan has a very good point, though: unless you know the seller to be honest, do your research and ask questions!

The ailing ICF-SW100

Vlado discovers the faulty ribbon cable (click to enlarge)

Back to my ailing unit: Vlado delivered the news about the ribbon cable via text message, and though I was well aware that the chances were high that was the ribbon cable, I was a little bummed, to say the least, to get the formal diagnosis.

Why? As Dan mentions above, you’ll find that the SW-100S upgrade kit Sony produced in the 1990s is no longer available new; sellers typically list these kits at prices in excess of $300 US. Out of my budget.

But Vlado, ever the intrepid engineer, had no idea I would be disappointed with this news; he was just giving me this FYI via text. Indeed, he seemed entirely unfazed, as in, hey, no serious internal damage here…

Another hour passed. Then came another message from Vlad; this one simply said: “Call me.”

Oh no, I thought. But I called, and Vlado answered cheerfully, “Hello? Tom, is that you? Sorry, I can’t hear you very well because your SW100 is playing too loudly. Hang on–let me turn the volume down!”

Vlad installs the replacement ribbon cable (click to enlarge)

“What!?!” I responded, in utter disbelief.

Yes, he’d got it working! It seems that Vlad had unearthed an old DVD player in his garage that he’d kept merely for parts. He opened it up, identified a ribbon cable with the right pitch, then cut and folded the cable to fit into the SW100. Ingenious!

That’s Vlado for you!

And should I be interested in replacing this used cable with a new one–or in repairing other Sonys–Vlad directed me to eBay listings for new cables which only total about $20, shipped. Truthfully, I’m in no hurry, as this one is functioning perfectly and changing out the ribbon cable seems to have no effect on stored memories, etc. With a single affordable eBay purchase of multiple cable sets, it occurred to me that Vlad would have enough replacement cables to repair the SW100 many times over…

So I bought the cables. (This one for the narrow cable and this one for the wider one.)

My “new” Sony ICF-SW100

Needless to say, I’m very pleased with my “new” (to me) SW100. It’s a little masterpiece of receiver engineering in such a tiny package. And since the ICF-SW100 is unquestionably the smallest portable I own–and is one of the few I own with a proper line-out jack–it may very well become my go-to radio for one bag travel.

It’s in the bag: listening to the ‘SW100 before I pack it for my next trip!

Stay tuned the review…

Vlado’s radio E.R.: the doctor is in

As I’ve said, Vlad is one of the most adept repair technicians I’ve ever known. At my prompting, he’s kindly agreed to let me promote his services here on the SWLing Post. Vlad acknowledges that he “likes a challenge,” adding that he enjoys nothing more than making repairs even when”parts are scarce” and radio”surgery” is required. Moreover, his bench fees will be quite reasonable, especially considering what you receive: new life for a failing radio. So, if you’ve got an ailing rig on your hands, and don’t mind waiting for Vlad to get to it, send it to his radio emergency room, where radios (like my Sony) have life breathed back into them once again.

Long live the Sony ICF-SW100! And long live Dr. Vlado, who makes this possible with his creative (and nearly miraculous) repairs.

To contact Vlad, simply contact me with a description of your radio and its problem and I’ll put you in touch with Vlado.

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Silicon Labs DSP chip homebrew receiver

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The Silicon Labs Si4730 series DSP receiver chip powers many of the portable shortwave radios currently on the market.

Manufacturers are not the only ones implementing the chip in receiver design, however; radio enthusiasts are too.

I recently discovered this short video by a Japanese hobbyist who implemented the Si4734 in his receiver design:

While I don’t speak Japanese, the author also has a webpage of detailed design notes you might check out (click here to view). I used Google translate for a rough English translation of the page.

Have any readers made a homebrew receiver from a Silicon Labs DSP chip? If so, please comment!

Click here to download the Si4734 product information sheet.

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A three transistor homebrew shortwave radio

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(Photo source: Instructables)

SWLing Post contributor, Richard Langley, writes:

Came across this site on building a 3-transistor shortwave radio similar to the kit offered by Radio Shack years ago:

http://www.netzener.net/index.php/8-project-articles/5-3-transistor-short-wave-radio

It was featured on the Instructables site:

http://www.instructables.com/id/Three-Transistor-Short-Wave-Radio/

Very cool! Thanks for sharing this, Richard.

When I have a little time, I’ll go through my parts box and see how many of these components I already have. The author also supplies an excellent assembly manual for download and print. It would be fantastic if someone would kit up the parts list and offer it as a package. Regardless, this will make for a fun winter project!

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