What you see is a circuit board, a battery (lower left) and the speaker lower right.
The story starts with how weak the speaker sounds. I thought some earphones might help but they didn’t; in fact, I could barely hear anything on earphones. Perhaps an obvious flaw in the earphone jack could be found. Opening the radio proved an adventure. One can see a rather substantial screw pillar on the lower right; this is coming from the back of the radio. Three screws came out with some effort, but the 4th screw just spun around with no effort. It turns out that the screw head was broken off (not by me), leaving the rest of a very long screw holding both parts of the case firmly together. The only solution that worked was to use a fine-tipped soldering iron to heat the screw enough to melt the plastic to release it.
Remarkably, the radio still works as you see it in the photo. The phone jack is soldered onto the board and leaves nothing obvious to inspect. I asked a question about fixing the earphone jack on the Si47XX for Radio Experimenters Facebook group, and got this reply:
Bluetooth transmitter and Bluetooth speaker is the simplist
If you look closely at my photo, there is the phrase “WiFi + BT Model” and an antenna is etched onto the board above the chip, leaving the question 0pen whether it’s already capable of Bluetooth or not [Update: it does not. The audio signal is not connected to the Bluetooth input.] . I put on V1.01 of the G8PTN software where I specify ESP32-S3, the chipset I have. The photo also indicates that the chip has 16 MB of flash memory (some have less).
A bit more research on Reddit finds others complaining about the audio level of the earphone jack, so it’s not just mine. In fact, the included Quick Start Manual doesn’t call this 3.5mm hole in the side of the case an earphone jack, but rather an “external speaker” jack.
I have a Bluetooth speaker (Sony SRS-XB20) that conveniently has a 3.5mm input jack, too. Here’s the result:
That Sony speaker is not something I would try to put in a pants pocket, but I have another option, a Tecsun Q3; it has a Line In jack, plus a record capability. In the comparison that follows, the Q3 is connected first and the Si4732 Mini internal speaker is second:
I’ve enjoyed the Q3 as a recording accessory. It can be purchased on eBay from Anon-CO for $27.99 plus $110 shipping from Hong Kong (tariffs).
The one drawback to the two solutions preceding is the lack of stereo. I can think of a couple of approaches. One would be to use two radios with Line In capability and a splitter cable to get stereo. The blurry black radio behind the Q3 in the video above happens to be a Zhiwhis ZWS-603 that has just such an input, and a pretty decent speaker (check out the video).
An alternate approach is to just hook up something stereo to it, which I did.
The obvious drawback is the reduction in portability.
I must say, I’m liking this radio a lot more now that I have a good speaker on it and have a user interface that doesn’t fight me (firmware update).
My happiest discovery relates to tuning. The radio has 20 Bands, listed below:
| Band | Range (kHz) |
|---|---|
| Band | Range kHz |
| MW1 | 159-1720 |
| MW2 | 531-1701 |
| MW2 | 1700-3500 |
| 80M | 3500-4000 |
| SW1 | 4000-5500 |
| SW2 | 5500-6500 |
| 40M | 6500-7300 |
| SW3 | 7200-8000 |
| SW4 | 9000-11000 |
| SW5 | 11100-13000 |
| SW6 | 13000-14000 |
| 20M | 14000-15000 |
| SW7 | 15000-17000 |
| SW8 | 17000-18000 |
| 15M | 20000-21400 |
| SW9 | 21400-22800 |
| CB | 26000-28000 |
| 10M | 28000-30000 |
| ALL | 150-30000 |
| VHF | 64-108 MHz |
One super feature of the ALL band is its ability to streamline frequency tuning with minimal dial twirling. For example, to quickly reach CHU at 14.670 MHz, you can:
- Set the BAND to ALL and the STEP to 1 MHz, then turn the dial to 14 MHz.
- Change the STEP to 100 kHz and adjust to 14.600 MHz.
- Finally, set the STEP to 10 kHz and fine-tune to 14.670 MHz.
This method lets you efficiently reach a target frequency without excessive dial turning. 
[applause emoji] Testing suggests that the radio has to be in AM mode for the 1 MHz step to be available.
Antenna
One early conclusion is: lose the donut. That antenna is not very sensitive. I ordered a SMA-base telescopic antenna to replace it (some versions of the radio include a telescopic). I have a 30″ halfwave dipole antenna that came with my RTL-SDR V3 for use on FM and of course there is the 4o-foot long wire outdoors.
FM
The FM band extends all the way down to 64 MHz. I found reception good. I tried the band scans after the telescopic antenna arrived. MW was abysmal as expected (and no better with the donut). FM was about average. (Scroll down to the line with a blank brand.)
FM step can be set to a number of values, including the North American standard of 200 kHz — very convenient for band scanning. Be sure the radio is tuned to a real frequency before setting the step so it lands on the correct values as you tune.
FM provides RDS data on the display, although it seemed limited and sometimes distorted because of the small text area available.
Shortwave
The MLA-30+ active loop antenna is conveniently terminated with an SMA connector, that hooked up smoothly. WWV was still strong at 15 MHz still at 9:45 PM local time. CFRX, 6070 kHz, Toronto, 400 miles from here had a decent signal. I dropped down to 7200 kHz to listen to some ham radio traffic and give SSB a whirl. It worked OK in my brief test. USB and LSB are selections under the Mode menu. Once selected, I went to the set menu to set the STEP to 10 kHz. Fine adjustment to the signal is how clarifies SSB; there is no BFO adjustment.
This firmware’s user interface makes sense and I was able to tune SSB without a manual.
Calibration
It has an SSB calibration feature, an offset in 10 Hz increments to add or subtract from the BFO frequency. I only tried it briefly on the pirate radio station on 6950U (Wolverine Radio?). I see how it works, but the program content was music and I find SSB tuning on music next to impossible. CHU in Canada operates using USB, providing three reliable signals. While the carrier is “reinserted” to make CHU AM compatible, it is an SSB signal. SSB calibration has to be done on each band. Calibration on the ALL band and SW3 resulted in a +630 calibration number (or +620 maybe). I’ll try it on 3330 (MW2-2) and 14670 (20M) when those signals are available. The calibration on my Tecsun PL-990 seems to be spot on, so I could use that to find stations with their frequencies.
MW
MW worked and I got plenty of stations in the evening. There is no mini ferrite MW antenna inside the radio. You have to supply an external antenna and the MLA 30+ handled that requirement. MW is a bit confusing in that there is an MW1 band and TWO MW2 bands. MW1 seems to be set up for what I would call LW, dropping down to 150 kHz. The first MW2 band seems to be the North American broadcast band, defaulting to 10 kHz step, although that can be changed. The second MW2 band starts off at 1700 kHz and ends at 3500 kHz.
Like my ATS25 max-Decoder, this is more of a tinkerer’s radio. Firmware updates are a normal part of product usage. The SI4732 Pocket Mini is small enough to put in a pocket, but in practice one needs to carry around some sort of antenna and an external speaker and for pleasant listening.
Improvement
Of course, now that I have my radio, an “improved” version version has come out. It has greater sensitivity due to a high-impedance antenna modification, an amplifier upgrade that makes the earphone jack output louder, and reduced hiss overall. It also has a silver knob. Here’s a video from OM0ET about the new version (he changed his knob):
I found one on AliExpress but they estimated delivery in mid-July.
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