A red radio — the Prunus J-429SW

Can you say “Big black rubber buttons” three times really fast?

The big picture

The Prunus J-429SW (sometimes called an L-238 SW) is an AM/FM/Shortwave radio with the ability to play MP3 files from a TF/Micro SD card or a USB flash drive. It can also act is a speaker when wired to another device with an AUX or earphone output. It’s powered by a BL-5C battery. The Prunus is available on Amazon for $19.99.

Prunus J-429SW (Amazon photo)

This model radio seems to be marketed to seniors, touting simplicity of operation and a highly readable display with large buttons.

Specifications

BrandPrunus
ModelJ-429SW
AM522-1710 kHz (See Note 1)
FM87-108 MHz (according to the box)
The radio actually tunes 70-108.
SW2.3 – 29.50 MHz
MP3 PlayingTF Card / USB flash
Input PowerDC 5V 500 – 1000mA
Battery 1200 mAh BL-5C (battery included)
Charging time3-5h
Playing Time5-6h (3-% Volume)
Speaker50mm 4Ω 3W
Earphone3.5mm
Dimensions31 * 126 * 73mm
Weight28g (radio) + 25g (battery)
IncludedRadio, battery, user manual, USB charging cable
Prunus J-429SW Specifications

Generally, an AM frequency range starting with 522 kHz indicates a radio intended for the European/Asian market where the frequencies are in 9 kHz multiples. Radios for the North American market start at some multiple of 10, like 520. For radios with digital tuning this is a big deal unless the radio can be switched from one configuration to the other. This radio, however, tunes in 1 kHz steps, so it doesn’t matter. Testing confirmed that AM actually works, but it is the weakest of any radio I own.

Casual use as an FM radio

It’s not unusual for an inexpensive radio to perform well on FM, and this is no exception, clearly pulling in 17 stations with the 10″ telescoping antenna. The sound is good and you can turn the speaker up very loud. So it’s fine as an FM radio.

The radio, however, has somewhat peculiar tuning in that you can’t exact tune across the band manually. The radio has 3 tuning modes:

  • Direct frequency entry – just key in the frequency and the radio will tune it.
  • Scan/Memory – Long press the “Scan” button and the radio will scan the selected band and store all the stations found in non-volatile memory. The user can then use arrow keys to select the next or previous station
  • Scan – Long press one of the arrow keys and the radio will scan forward to the next received station and stop.

Shortwave radio

I’ll probably have more to say about this, but my initial test found that the shortwave section of this radio was deaf as a post. What would you expect with a 10″ (25.4 cm) antenna? Clipping on another 20 ft. of wire helped a lot and I actually received a station in China from here in central Virginia loud and clear.

China Radio International on 17.880 MHz.

I’m an old electronics hobbyist from way back when 7-segment LED readouts were starting to be used; they made a lot of electrical noise, and apparently they still do. Particularly on the lower frequencies there is a very annoying buzzing sound when there is no strong station. The display shuts off after 1 minute if no button is pressed, and when the display goes off, the buzz goes away too.

As a speaker

Some radios like this can be used as a USB computer speaker, or even a Bluetooth speaker. This one has none of those feature. It works only via an audio cable plugged into its AUX port.

Just as a quick test, I tuned an FM talk program on a very well-regarded shortwave portable (costing a lot more), the Tecsun PL-330. I listened, and then I plugged the output into the AUX port on the Prunus, and the improvement in quality was stark.

Sound with headphones is good too. The User Manual says that the radio mutes when you unplug the headphones, but this feature does not work.

There is what appears to be a bass port on the back of the radio, but closer examination shows that the plastic is solid behind the perforated decorative grill, and no sound is heard coming out of it.

MP3

I put a TF/Micro SD card in the radio and it played MP3 files on the card. One can go directly to a particular track by entering a track number on the pad.

Big black rubber buttons

There’s no getting around the subject, the buttons are big, black and rubbery. Someone having difficulty operating or reading small buttons will find this welcome.

Conclusion

Someone looking for a shortwave radio could do better. Someone wanting an FM radio that plays MP3 files and is physically easy to operate might do well with this radio.

About Kevin

Just an old guy with opinions that I like to bounce off other people.
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