I bought the Zhiwhis version (ZWS-603) in April of 2022 and I learned that there had been firmware updates since my V1.6 radio to V2.4. Zhiwhis tech support told me that my older radio couldn’t be updated to the latest firmware; the circuitry had changed.
When I saw an ad for the HanRongDa K-603 version for $14.55 with shipping, I snapped one up. The original Zhiwhis version came in white or green display backlighting, mine green. I wrote about the ZWS-603 in my article: ZHIWHIS ZWS-603 Shortwave Radio Review. Refer to that article and Zhiwhis ZWS-603 vs Kaito KA29.
Amazon sells the ZWS-603 now at the end of 2025 for $24.77 ($20.06 with coupon) and the K-603 for $24.99 ($22.49 with coupon).
What’s Old
This is a MW/FM/SW radio that covers 64-108 MHz FM, 520-1710 kHz MW and 4.75 – 21.85 MHz SW. It’s also a Bluetooth speaker, USB speaker and MP3 player from MicroSD card. Further, it records from radio, Bluetooth, AUX and an internal microphone.
What’s new?
The first obvious change is the USB port, now USB-C instead of the older USB Mini. The next is the firmware version, the new radio with V2.4. The K-603 comes with two manuals, one a fold-out “Function Schematic” showing the buttons and what they do in 6 languages, and an English “Instruction Manual” of 27 pages plus a table of contents. My early ZWS-603 manual was only 14 pages with smaller pages and smaller print. I believe the older radio came with a carry pouch, but not the new one.
Radiomuseum points to a new PCB assembly K603BT-W-2024.1.8. To my ear, the volume is a little louder for the same setting on the new model.
One difference I discovered in the menu system is its timeout. If nothing is pressed on the main menu display, the old version after 5 seconds of inactivity switches to the Auto Power setting (sleep timer), and if that is ignored it eventually exits the menu. In V2.4 12 seconds of inactivity exits the menu. Auto Power is a separate menu item in both versions.
The radio has + / – buttons labeled “Volume.” Under V1.6, pressing a volume button cycles through stored station memory; a long press is required to change volume. Under V2.4 a press changes the volume and a long press changes the volume faster, a welcome change.
There appears to be some differences even between the V2.4 editions; for example, the ZWS-603 manual says the supported languages are Spanish, English and Japanese, while the K-603 supports Chinese, English and Japanese. The manuals are distinct between the HanRongDa and Zhiwhis versions, even though both are labeled with V2.4. The ZWS-603 manual calls the MENU button “MEMU” and the K-603 manual confuses the fast-forward symbol with the play/pause symbol symbol in the text. Both manuals incorrectly state that the USB cable is a Micro type, and that the “Bluetooth version” is “5.0GHz.” The HanRongDa manual is the only one showing TF card play of .WAV files.
One curious thing is that there is no conventional tuning in the sense of a tuning knob with steps. Tuning is either ATS (auto tune and store), search for the next station or direct frequency entry with the number keys. Direct frequency entry allows 100 kHz step, 9/10 kHz step on MW (menu setting) and 5 kHz on SW.
In a side-by-side comparison on an empty channel, 6030 kHz, there was a sputtering sound, on both, I assume noise from the display.
Broken
I tried a 16 GB MicroSD card in the K-603 that I have used with other media players. It was not recognized by the radio, while it worked fine with the older ZWS-603. Another smaller card worked OK in the K-603. Left and right stereo channels played from MP3 are reversed on both radios.