The radio nobody wanted Kaide KK-MP903

I sold about 80 radios on eBay, but there were just a few that nobody wanted. I went through those to see if there was anything worth saving from storage. One radio looked like it might be worth further study, a Kaide KK-MP903.

Kaide KK-MP903 AM/FM/Shortwave radio / MP3 player

It’s a remarkably simple radio, with only 4 buttons, a volume wheel and a tuning wheel, but it is an 11 band radio, clock, alarm, calendar and MP3 player. The radio uses 2 AA batteries and has an earphone jack and a jack for an external 3V power supply. The antenna extends to 17.5″ and swivels allowing it to be vertical when the radio is on its kickstand, a fob on the end of the carrying strap.

It has AM (MW), FM, FM1 (70-88 MHz) and 8 shortwave bands from 5.95 – 21.85 MHz. The chart later on shows discrete ranges for the bands, but in practice, there are no gaps between bands; coverage is continuous. Tuning is digital. Repeatedly pressing the FM button switches between the FM and FM1 band. Repeatedly pressing the SW button sets the tuning to the start the next shortwave band.

Inserting a micro SD/TF card in the slot in the side converts it to an MP3 player. The same 3 radio operation buttons work as MP3 player controls, with function labels on the top of the radio.

This description was found on the internet, translated by Google from simplified Chinese:

The performance improvement brought by DSP technology to this radio section product: digital filtering, strong selectivity, no tandem; full-band frequency tracking and locking technology, no image and frequency drift phenomenon in short-wave reception; digital processing technology makes the sensitivity comprehensively improved, There are many receiving stations; built-in digital power amplifier, high power, low distortion; FM stereo output.


Also at the same site these specifications:

  1. Frequency coverage
    FM: 87 -1 -108 +1 MHz 
    MW : 520 -60 – 1710 +60 kHz
    SW1: 5.95 – 6.20MHz 
    SW2: 7.10 – 7.30MHz 
    SW3: 9.50 – 9.90MHz 
    SW4: 11.65 – 12.05MHz 
    SW5: 13.60 – 13.80MHz
    SW6: 15.10 – 15.60MHz 
    SW7: 17.50 – 17.90MHz ( Shortwave frequency coverage is not narrower than the above requirements ) 
  2. Noise limiting sensitivity 
    FM : 30 Noise Limit Sensitivity 10 dBu 
    MW : 26 Noise Limit Sensitivity 70 dBu 
    SW : 26 Noise Limit Sensitivity 35 dBu 
  3. Signal-to-Noise Ratio 
    FM: 98 MHz    ≥ 50 dB 
    AM : 1000 kHz  ≥ 40 dB 
  4. Selective MW: 1000 kHz   +/- 9 kHz  ≥ 40 dB 
  5. FM stereo separation: ≥25 dB 
  6. Maximum current consumption: ≤ 180 mA 
  7. Maximum output power: ≥100 mW, maximum distortion ≤ 20 % 
  8. Size: 124*77*21mm

A brief test using just the whip antenna picked up many stations on shortwave. Here’s Radio Romania International on 7420 kHz on June 5 at 0010 UTC heard in central Virginia.

Kaide KK-MP903 AM/FM/Shortwave/MP3

The functions of the 4 buttons were easy to discover. There are basically 3 sets of functions, when the radio is off (clock, calendar, alarm functions with dates and time selected with the tuning wheel), when the radio is on (band selection), and when the radio is on and a micro SC/TF card is inserted (next track, play/pause, previous track). Counterclockwise rotation of the tuning knob increases frequency.

The small speaker does not produce rich sound on radio, nor is there any significant bass response even with good earphones. Sound is much better playing MP3 files.

The display is large and easy to read. In radio mode, the band is displayed along with the time and frequency. There is also a stereo indicator for FM. When the radio is first turned on, a button is pressed, or the tuning wheel turned, the display is illuminated with a pleasant orange glow. When the radio is off the radio displays the date and time. In MP3 mode, the radio displays the time of day, the track number and the elapsed time played in the current recording. It does not play files in the WMA format.

My only puzzle is how (if possible) to set the AM tuning step to 10 kHz instead of 9. I’ve found virtually nothing about this radio on the internet. I probably bought it on eBay a dozen years ago. One Chinese exporter still sells it for $25 (one presumes it’s legit).

Posted in Radio, Technology | Tagged , , | Leave a comment

Zhiwhis ZWS-603 vs Kaito KA29

Two radios with similar function, but significant differences

The Kaito KA29 received a lot of attention by reviewers when it became available in August of 2014, but I only got mine today. The Zhiwhis ZWS-603 is much newer, from December of 2021.

Kaito KA29 AM/FM/Shortwave radio MP3 player front view.
Kaito KA29 ( photo)
Zhiwhis ZWS--603 AM/FM/Shortwave radio, MP3 player, Bluetooth speaker
Zhiwhis ZWS-603 ( photo)

There are some striking similarities in the radios, inviting a comparison. At the most basic level, both units are AM/FM/Shortwave radios that add the capability to be used as external speakers, to play music files from TF/SD and record from radio or from the microphone. Both use the same BL-5C rechargeable battery format. Both have a graphic equalizer and fall into the “ultralight” radio category. The ZWS-603 goes for $25.77 on Amazon, compared to $34.99 for the KA29.

Examples of similarity include a power button that requires a long press, a button immediately below it that locks the other keys and a mute button. And check out the similarity in what happens when you turn them off:

Photos showing "GoodBye" and "Bye Bye!" exit screens.

Here is the display when music is playing:

Images showing similarities in the radio display when playing audio files.
Audio play menu (ZWS-603 on top)

Both are supposed to be usable as computer speakers, the Zhiwhis via Bluetooth and the Kaito with a USB cable; however I couldn’t get the Kaito to work as a USB speaker with Windows 10.

Both radios have a a music equalizer for different styles of music (pop, rock, jazz, classical, bass and normal) when playing from media (not for the radio, darn it). Both display music lyrics from .LRC files when playing a music file with the same base file name. Both support browsing music files from their directories and selecting them by name — a major advantage.

Both radios have a button to mute the speaker when playing radio. It’s a speaker mute button on the Kaito and a Play/Pause button on the Zhiwhis.

The obligatory feature matrix

Manual16 pages 32 pages
Frequency coverage (MHz)FM 64-108
MW .520-1.710
9/10 kHz step
SW 4.75-21.85
FM 64-108
MW .520-1.710
9/10 kHz step
SW 3 – 23
Shortwave bands8 with continuous tuning12 with gaps between bands
MusicMP3, WMA, LyricsMP3, WMA, WAV, Lyrics
ClockNoYes / Alarm
Sleep timerYesYes
Play computer audio
Access/copy files
C0mputer audio gives error
Access/copy files
Firmware VersionV1.08 (12/24/2015)V1.6
Media supported32G Micro SD/TF32G Micro SD/TF
USB 2.0 Flash
Tone control7 Equalizer categories for music play only7 Equalizer categories for music play only
22 Languages (including
English, Chinese, Korean
Arabic, Russian, Japanese)
Weight w/battery167 g (measured)186 g
Size120 x 79 x 25 mm131 x 76 x 27 mm
KickstandPlug in
MemoriesFM 80
MW 60
SW 300
1000 (per box). Manual says FM 440, AM 132, SW 928.
RecordingFrom Bluetooth
Zhiwhis ZWS-603 – Kaito KA29 comparison

The elephant in the room

There is one thing that I hate about the ZWS-603. While its bright green display is eminently readable, the labeling on the buttons is the most difficult to read of any radio I have ever encountered and virtually impossible to use except in bright lighting. The key captions are tiny and they’re grayish white on black. It’s darn frustrating. I don’t recall having problems with other radios; I can read the Tecsun PL-330 key labels OK. The Kaito has big bold black captions on shiny silver buttons. Outdoors, they would both be fine.

One negative with both radios is that they do not timestamp the audio recordings. The Zhiwhis has no clock and couldn’t be expected to save the time, but the Kaito has a clock and doesn’t use it.

The Kaito manual says it can be used as a computer speaker over USB, and Windows 10 recognizes the audio device as an AC309N voice recorder, but gives an error when one tries to use it.

Screenshot showing Kaito radio listed by Windows as an audio device: Speakers (AC309N)

Some differences of note

The most obvious difference is that the Kaito has a knob for tuning–buttons only for the Zhiwhis.

Both have labeled volume up and down buttons; however, only the Kaito buttons work by pressing them while using the radio. The Zhiwhis “Volume” buttons advance through the preset radio memories, and only do volume by press-holding them (except when playing music).

The Kaito adds a text-reader function. Files with the extension of .txt on media are displayed on the screen. Here’s a sample:

Photo of Kaito KA29 displaying a text file.
Text reader on KA29 display

Another significant plus for the Kaito is its support for a USB 2.0 flash drive.

While I wouldn’t describe either as HiFi, the Zhiwhis with its more powerful 3W speaker and bass port is richer in sound and can be turned up louder without distortion.

I mentioned that the Kaito has a clock. One nice feature is the alarm, which can be set to ring once, or daily or on specific days; for example, you could set the radio to alarm just on Tuesdays and Fridays. One can either use an alarm tone or the last radio station listened to.


Oh yeah, these are radios. So I started with a strong shortwave station (WRMI) and both radios received it well, but there was a marked difference in selectivity between them. Strong stations could be solidly heard on frequency and +/- 5 kHz on either side, with occasional bleed +/- 10 kHz for the Zhiwhis, while the two 5 kHz side frequencies were noticeably degraded and the +/- 10 was completely missing on the Kaito.

As I said before, the Zhiwhis speaker is notably better than the Kaito, but with quality earbuds, it’s reversed. Bass shines on the Kaito and the Zhiwhis has weak bass and a very noticeable high frequency hiss on shortwave (perhaps because of the wide bandwidth). I think one would get tired of the Zhiwhis listening to shortwave on headphones.

The KA29 manual describes continuous shortwave coverage between 3.00 and 23.00 MHz, but there are gaps that simply cannot be tuned, not by direct entry, scanning nor the tuning knob. 19.305 – 21.155 is one such inaccessible range. Shortwave is divided into 12 bands that can be accessed through repeated pressing of the SW button.

  • 1: 3 – 3.6
  • 2: 3.7 – 4.2
  • 3: 4.5 – 5.7
  • 4: 5.8 – 6.4
  • 5: 6.9 – 7.6
  • 6: 9.2 – 10.1
  • 7: 11.4 – 12.3
  • 8: 13.4 – 14.1
  • 9: 14.9 – 16.0
  • 10: 17.3 – 18.1
  • 11: 18.7 – 19.3
  • 12: 21.2 – 23.0

Notice that the bands do not overlap, so many frequencies on the Kaito are omitted. Tuning, by key or the knob, is within band only. When reaching the end of the band, the radio wraps around back to the beginning, rather than advancing to the next band. Switching to the next band with the SW button takes about 1.5 seconds.

Direct frequency entry works on both radios by keying the frequency and pressing a key. The key is the Play/Pause key on the Zhiwhis and the labeled band key (AM/FM/SW) on the Kaito.

I was pleased with the Kaito because it didn’t “chuff, chuff, chuff” when I turned the tuning knob. It mutes the radio when tuning. This advantage is offset by the fact that it takes about a second for the station to appear after stepping to the next frequency.

There are several things I have noted that I think could be fixed in firmware. The Operation Manual I received with the radio has listed “Firmware Upgrade” listed in the table of contents, but it does not appear in the manual itself; however, the manual I found online (see references at end) has the procedure. Kaito told me in an email that there are no update for this radio.

The ZWS-603 is almost identical (based on button layout and manual) to the Retekess VT115 from 2016, the only difference being support for Bluetooth and a more powerful speaker.


Posted in Radio, Technology | Tagged , , | 2 Comments

Radio nostalgia

Here’s my nostalgia photo from December of 1967. My “radio shack” was a bedroom closet.

My “radio shack” from December, 1967

The Eico signal generator, the Lafayette KT-340 shortwave receiver and the Heath kit IO-21 scope were all built from kits. Sort of in the center is my first shortwave radio, a Nanaola 10NT-504, 10-transistor single conversion radio that covered LW from 145-375m MW, and shortwave from 1.8 to 28 MHz in three contiguous bands. It had Vernier tuning. Great little radio.

On the wall I can recognize QSL cards from Radio Moscow, RCI, CHU, WWHV, Radio Japan, K4USA and WNYW.

In the same file box where I found the photo, I found the instruction sheet for the 10NT-504, which I’ve scanned for posterity. Also in that box was my very first radio:

Gilbert series-tuned “crystal radio” schematic and build sheet

Posted in General, Personal, Radio, Technology | Tagged , , | Leave a comment

ZHIWHIS ZWS-603 Shortwave Radio Review

The ZHIWHIS XWS-603 appears to be the same radio as the HanRongDo K-603.

Zhiwhis ZWS-603 front view
Zhiwhis ZWS-603 radio, Bluetooth speaker, MP3 player

What’s unusual about this radio

This one is not like anything I’ve used before in several ways. First, it combines a shortwave radio, an MP3 player, a sound recorder and a Bluetooth speaker.

I’ve come to expect digital displays to consist of 7-segment digits, or predefined messages or bars on the display, but the ZWS-603 is a general dot-matrix screen. This means that it can display menus and draw pictures. It can switch languages and display English, Chinese and Japanese. Also because of the dot matrix design, the radio can put up very large characters, including a very visible frequency display.

XWS-603 Screen Detail

While the display is visible, the button labels are tiny and very difficult to read except in strong light.

One feature that I have never before seen in a portable shortwave radio is a “Mute” button. Just as MP3 players have a Play/Pause button, this radio uses the same button provided for its MP3 function to mute the radio. It’s great for comparing radios.

The radio has relatively few buttons for its functionality, which means that many of the buttons serve dual functions. Multi-use buttons are not unusual, but these will take some getting used to. The volume control doubles as a “next station memory” button with a long-press to change the volume. The MP3 Next/Previous track doubles for up/down tuning in the radio, since it has no tuning knob (or knob of any kind).

In actual use, I didn’t find myself stumbling because of multiple use of a button (something that has been a problem with my Tecsun PL-330).

USB functionality

I plugged a USB cable into the radio and my Windows computer’s USB hub. Nothing happened except that the battery in the radio started charging; however, when I explicitly followed the instructions by plugging in the supplied USB cable directly into the computer, Windows installed a driver for the radio. Once that was done, two things happened. The radio became a speaker for the computer, and the TF card in the radio because accessible as a disk for the computer, where I could copy files. I’m happy to report that music files inside directories are accessible by the radio. When playing a music file, the file name is displayed. According to the advertising, it will also display lyrics for files with them. [Update: I had a defective USB cable.]

Note that the radio cannot be used when the USB cable is connected to a computer, although it can be used when connected to a dumb charger.


The ZWS-603 is also a Bluetooth speaker. Switching between MP3, auxiliary audio cable (supplied) or Bluetooth input is accomplished with a Mode button.

I was readily able to connect the radio to my Samsung TV via Bluetooth, but I had to try twice before it showed up on my Windows computer. It also paired with an iPhone.


MP3 is rather straightforward. It has a the typical controls for Next track, Previous Track and Play/Pause. It displays the file names on the screen. When plugged into the computer, songs can be copied directly to the TF/Micro SD card in the radio.

The user can pick a particular song by number, entering the number on the numeric keys. It plays well with folders. Songs can be selected by:

  • Select all songs
  • Repeat the current song
  • Repeat songs in the selected folder
  • Play random songs


This device is sold as a radio, and it is that. As it comes, the full low FM range is available and the AM step is 10 kHz. The shortwave step is 5 kHz.

I’ll say right off the bat that AM performance sucks. At midnight I could not get a single clear AM station. I could hear stations but all were very noisy. FM was good as was shortwave, not on par with my Tecsun PL-660, but still competitive.

I tried daytime reception of WWV on 15 MHz around noon local time. It was a weak signal on my PL-330, but very weak on the on the ZWS-603 (with a shorter antenna), but it does demonstrate that the radio doesn’t mute very weak signals.

The MP3 track controls double as tune up/down buttons, and long presses scan for the next station. Repeatedly pressing the SW button selects the various shortwave bands. You can also enter the frequency directly on the number keys and short press Play/Pause. Stepping is quite slow, about 1 second per frequency change.

There are memory presets: 80 on FM, 60 on MW and 300 on shortwave. Stations can be stored manually by long-pressing the 5 key (sub-labeled MEMO), the number, and pressing Play/Pause. Long pressing Play/Pause starts a memory scan with automatic storage.


Recording can come from 4 sources:

  • Live sound recording
  • Aux input jack
  • Bluetooth
  • The radio

While the recordings are stored on the TF card, they are placed in different folders on the TF/Micro SD card. FMRECORD, for example, is the folder for radio recordings (not just FM) and microphone recordings go into the MRECORD folder. I thought the microphone recordings were quite good. Recordings can be made in 3 quality levels with 128-bit sampling the default.


The ZWS-603 is not going to take the world by storm. It doesn’t have sync/SSB reception. It’s not as sensitive as the Tecsun PL-330/PL-660 radios. There’s no tone/bandwidth control. It’s memory system lacks features. It doesn’t have a clock, and hence no alarm (it does have a sleep timer). However, the wide range of record/playback capability, Bluetooth, the imminently readable display, the compact size/light weight and a very nice speaker make this $25 radio a good deal. If the button labels were easier to read, it would be a keeper.

Posted in Product Reviews, Radio, Technology | Tagged , , , | Leave a comment

Unboxing the ZHIWHIS ZWS-603

My pet peeve about “unboxing” videos is that invariably the item being unboxed was already unboxed before the video, and often not even in the box. This isn’t a video, but this series of photos is authentic, and taken as the radio was being unboxed.

The radio comes with:

  • ZWS-306 radio
  • Plush carry pouch
  • 14-page instruction sheet
  • Audio cable
  • USB cable
  • BL-5C rechargeable battery

The radio covers AM/FM and shortwave between 4.75 and 21.85 MHz.

My first reaction was that the radio was broken because every radio I’ve ever had with a digital display displays a clock after batteries are inserted, but not this one — it doesn’t have a clock. After I remembered that I just pressed the Power button. It didn’t come on. Rather than a separate lock button, this radio requires a long press to turn it on and off. Once I figured that out, the bright green display welcomed me (it actually says “welcome”).

This is my first radio with a menu interface. I was able to tune stations without consulting the instructions, but I will definitely need to read them to get much farther.

This is my first use of the WordPress gallery feature.

Posted in Radio, Technology | Tagged , , , , , | Leave a comment

Great price?

I’m completely recycling my shortwave radio inventory, selling mostly, but I bought a couple of new ones to check out.

One new one I ordered this morning was an XHDATA D-808. It’s feature rich, combining SSB with Air band and RDS. One expects a feature set like that to cost at least $80, and I wouldn’t have bought at that price, but AliExpress offered it for half that:

AliExpress listing for XHDATA D-808 radio

In the end, the order totaled $39.36 including shipping.

Just for grins, I checked eBay to see if I could have gotten a better deal. Apparently not. Here’s one offer:

eBay listing for XHDATA D-808 radio

I wondered how that “GREAT PRICE” came about; eBay says:

A Great Price badge helps eBay shoppers quickly and easily discover high quality inventory at highly competitive prices. When a Great Price badge appears with your qualified listing, your item will get buyers’ attention because they know they’ve found a great product at a great price.

There were 2 offers on eBay at that price with the “GREAT PRICE” logo, and as far as eBay is concerned, that is a great price. There were a total of 36 listings for the radio on eBay, and including shipping that $100.98 is the lowest price, but there were many much higher than that, topping off at $285!

A little reading finds that this is not a new radio, but one from late 2017, shipped to the US for a short time, but then suddenly not available here. You can read about that at the SWLing site. There are also reviews of the radio at eHam, whose readers give it between 1 and 5 stars. One big negative they report is a poor memory management system, but I rarely use that feature.

So I’m either getting a radio at an extraordinary price, or ripped off.


Well, I guess I’m sort of ripped off.

AliExpress listing for XHDATA D-808 radio

Update 2

That last was just too good to be pass up, so I ordered 2 of them to sell on eBay. As I taught my children, it it sounds too good to be true, then it’s probably not true. Both Ali Express sellers failed to ship the radios and I got refunds instead. $100.98 is more than I want to pay for a radio that’s not especially better than what I already have, so I’ll just do without.

Posted in Radio, Technology | Tagged , , | Leave a comment

Deciphering the Kchibo KK-9615

The Kchibo KK-9615 is a Chinese AM/FM/Shortwave shirt-pocket radio from a decade or so ago. It has analog tuning and a digital display with clock and alarm.

I know of no English-language manual for the Kchibo KK-9615, but through trial and error I discovered how it works. Below is a labeled photo.

Kchibo KK-9615 Radio with Labeled Buttons

Radio operation

The power switch is on the side of the radio, lower right. The tuning knob is on the side of the radio, upper right. The volume control is on the side of the radio, upper left. To tune an FM station, flip the power switch downward, extend the antenna, press the FM button (see photo), and tune the radio with the tuning knob. The large display shows “FM” and the frequency below. To tune MW (AM) press the MW/SW button and set the band selection (top of radio) to MW. The display shows “MW.” To tune shortwave, again press the MW/SW switch and use the band selector to pick the desired shortwave band; the display shows “SW.”


Alarm On/Off/View

With the radio on or off, press the Alarm Off/on button to turn the alarm on or off. A clock icon will display on the radio screen to indicate when it’s set. To display the alarm time, press the View Alarm button.

Time/Alarm setting

To set the clock or the alarm time, first turn the radio off. Press and hold the Time 1 button while pressing the Time 2 button repeatedly to set the hour. Press and hold the Time 2 button while repeatedly pressing the Time 3 button to set the clock minutes. To set the Alarm time, press and hold the View Alarm button while repeatedly pressing the Time 1 button to set alarm hour. Press and hold the View Alarm button while repeatedly pressing the Time 3 button to set the alarm minutes.

Using the Radio

The most noticeable thing about the radio is how loud it is, especially for its size. The size is quite small; I measured 113 x 72 x 21 mm. I found reception to be good for a cheap pocket radio. Here is the frequency coverage:

Kchibo KK-9615 Back Detail
Posted in Radio | Tagged , , | Leave a comment