Exploring the ATS-Mini: A Pocket-Sized Receiver with Big Aspirations

A recent Reddit post sparked my curiosity about an ultra-compact, budget-friendly radio known as the ATS-Mini—also referred to by its technical title, the V3 AMNVOLT Mini SI4732 DSP Radio Receiver. It's quite a mouthful, but its description is certainly accurate.

I purchased the unit from AliExpress for just USD 23.71, and despite its modest price tag, it claims support for a wide range of frequencies:

• FM: 64–108 MHz with RDS

• LW: 153–500 kHz

• MW: 520–1710 kHz

• SW: 1730–30,000 kHz

FM reception was surprisingly good - with RDS PI and text

SI4732: A Familiar Core

The heart of the receiver is the SI4732 DSP chip, commonly found in many low-cost radios, including the Tecsun PL-990 and XHDATA D-808. These retail for around USD 300 and USD 100, respectively—making the ATS-Mini a notable bargain.

Despite its compact dimensions (80×34×19 mm, 58 grams including battery), the device is packed with functionality. It includes an ESP32 microcontroller with Bluetooth and Wi-Fi capabilities—features rarely seen in radios of this size and cost.

Community Impressions and Durability Concerns

The online reaction has been mixed. While some users report their units failing shortly after purchase, others praise the device’s capabilities when it works properly. As with many community-developed hardware projects, quality control varies, but the enthusiasm is unmistakable.

Real-World Testing at KONG HQ

As with all new receivers I get my hands on, I first measure sensitivity. Using one of my longwire antennas, I compared it to the SDRPlay RSPdx and found it performed admirably—receiving similar signals with only some differences in audio quality.

It also handled adjacent-channel interference fairly well. Encouraged, I brought out my signal generator to push the device further.

Small...Smaller...Mini!

Technical Performance

• Sensitivity: Surprisingly strong, measured at around −100 dBm (~2 µV) for most of the frequency range.

• Low-frequency sensitivity roll-off: Present, but expected in this price bracket.

• FM sensitivity: Not formally measured, but reception of weak Finnish FM stations was comparable to more expensive gear

• Strong signal handling is somewhat on the poor side: Saturation began at −47 dBm (S9+30) and became total at −27 dBm (S9+50); roughly 20 dB behind more robust receivers. I used a method where I set up a feed from a signal generator 200 kHz away from the tuned frequency for this test.

Alternative layout, emphasizing signal levels

Features and Functional Highlights

Despite limitations in signal handling, audio quality and durability, the ATS-Mini offers:

• Multiple reception modes including SSB. Yet, Synchronous AM is missing.

• RDS support for FM

• SMA antenna input, 3.5mm audio output, and USB-C charging

• Wi-Fi connectivity with support for access point mode

• Flexible firmware with multiple UI themes

• EIBI database support (still hit-or-miss for me)

The radio has no bandstop or bandpass filtering, making it effectively “wide open” and susceptible to overload in strong-signal environments.

Open-Source Ecosystem

What sets this receiver apart is the thriving community behind it. Developers and enthusiasts—many from GitHub—are actively enhancing both hardware and firmware:

• Enclosure and stand designs via downloadable CAD files

• A variety of tuning knobs

• Documentation for mods and firmware updates

• A growing library of shared knowledge and experimentation

While the user interface and jargon can feel daunting at first, this is part of what makes the project special: it's not just a product, but a collaborative effort.

Open for hardware mods! Not by this guy though... I've seen videos of people doing modifications with a soldering iron. Amazing.

Final Thoughts

Though it lacks the versatility of an SDR with wideband sampling, the ATS-Mini excels at what it sets out to do. It’s a simple, effective, and surprisingly capable receiver, ideal for travel or experimentation—just remember to bring a proper antenna.

For a device that costs less than a dinner out, its value is driven not just by the hardware itself, but by the passionate community improving it every day. It is a part of the radio hobby I haven't paid much attention to. And while the ATS-Mini is not the solution for hard-core MW DX-ers like myself, it will surely have a market.

Can Switching Power Supplies Be Quiet?

Over the years, there has been considerable discussion among DX-ers surrounding switching power supplies, particularly due to their tendency to generate radio frequency interference (RFI) affecting radio reception. German DX-er Werner Karn prompted me to revisit a manufacturer I had previously tested, after sharing on the Perseus reflector that his Perseus22 was being powered noise-free by a medical-grade 9V supply from Mean Well.

I had, in fact, evaluated Mean Well supplies many years ago during my quest for a suitable solution for my KiwiSDRs. While they performed reasonably well, they weren’t entirely noise-free, which led me to the tongue-in-cheek conclusion that “they meant well” but hadn’t quite hit the mark. It turns out, however, that Mean Well offers supplies in varying grades of quality. The one I had tried was an “industrial grade” GST-type unit, whereas Werner had opted for a “medical grade” GSM-type 9V model.

This piqued my interest, so I ordered a selection of 5V, 12V, and 19V models—the latter intended to replace a rather noisy PSU for a Dell micro desktop PC, affecting the lower shortwave bands. I’ve now tested all of them, and there's no sign of RFI whatsoever.

From what I can observe—literally, judging by pre- and post-test waterfall displays—none of the units produces any detectable noise across the frequencies we care about, i.e. 0–30 MHz, and especially MW.

They all look alike, so I had to add a bit of extra voltage info...

It’s my view that manufacturers of DC-powered devices tend to favour low-cost power supplies to keep expenses down, especially since end-users rarely pay attention to such details. Even reputable makers of commercial-grade routers like Teltonika adopt this approach. Yet quality supplies needn't cost the earth. A 4A, 9VDC medical-grade PSU suitable for the Perseus22 sells for around €20 each, roughly 1% of the radio’s retail price, and significantly less when purchased in bulk.

I’m not suggesting Mean Well is the sole producer of low-noise switching power supplies. I simply lack the time or resources to comprehensively survey that market. Still, the medical-grade GSM-type units I’ve acquired are as quiet as a traditional linear power supply.

Just a heads-up if you’re planning to order one (or several): the default DC connector is a 2.1 mm barrel plug (2.1×5.5 mm). They also offer adaptors for various other connectors at very fair prices—usually under €0.50. Also note that you’ll need a separate mains cable with a C7 connector—commonly known as a “figure 8” or “shotgun” plug. The plug converter guide looks like the image below.

See link above for better resolution

Mean Well is a Taiwanese firm. That may be of interest if you take geopolitical factors into account when making purchase decisions—I know I do. Yet, the actual product is made in China. So, there you go.