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I planned to do some testing of my top-of-the line Zhiwhis ZWS-C919 and discovered that FM stopped working. I tried the usual reset steps to no avail. Other bands worked, but FM was dead silent. I bought the radio in October of 2025, so it’s still under the 12 month manufacturer warranty.

Around noon today, February 27, 2026, I sent Zhiwhis an email:

Subject: Warranty Support

I purchased your ZWS-C919 through Amazon.com on October 6, 2025 (Order *************) and have used it occasionally. Today I found that the FM band is no longer working; when the FM band is selected there is no sound at all. AM, SW, Weather and CB have sound, but not FM. Here is what I tried:

• Tried other bands: worked OK
• Verified that the Volume control was set to 30 (and was not flashing)
• Tried the RESET under the power-off options
• Removed the batteries from the radio for 1 minute and reinstalled
• Tried multiple strong FM stations

If the radio is on the FM band when I turn it on, then signal strength graph is shown on the display but no sound. If I switch to another band and then back FM, there are SNR values shown, but the graph does not move.

Please indicate whether this can be remedied by the user, or provide a replacement.

Note: When the volume is flashing, the radio is muted. On other bands, pressing the >|| button turns mute on and off. On FM the mute button does nothing and the display doesn’t switch to flashing state.

I think the Chinese New Year celebrations are over. I’ll update when something happens.

Update:

Taking the batteries out for almost a whole day didn’t help.

The mute button works on other bands — muting the receiver and flashing the volume display, but on FM it does neither. That rules out a problem with the physical button. The radio is app controlled, so I thought I would try controlling the radio with the app. The >|| button on the app doesn’t do anything for radio on any band; however when that button is pressed on the radio a mute indicator on the app flashes, at least it did at first. Now the radio >||button doesn’t do anything on any band except wake up the display and turn on the backlight.

The C919 has a MicroSD card slot and can record radio. Using the app I was able to tune an FM station, record it, and then play back the recorded sound.

I had failed to mention that there no sound on LW either. After a couple of days, sound on MW stopped too. So LW, MW and FM are now silent. SW, CW and the VHF bands still work.

1. February 27, 2026 — Initial report to customer service
2. March 7, 2026 — Still no reply from Zhiwhis. Changed my Amazon review from 2 to 1 star.
3. March 11, 2026 — Received reply, suggesting I update the firmware. Attached was firmware file for V1.910 and a 38-page manual.
4. March 11, 2026 — Changed my Amazon review back to 2 stars.

Firmware update

I had considered a firmware update prior to the the failure, but the only update was available from Raddy, not the brand of mine. The Raddy material emphasizes that firmware updates should not be done unless there’s a need to do it (“If it isn’t broken, don’t fix it,” they wrote), because of the risk of bricking the device. But now the radio is broken.

Radio firmware updates usually take one of two paths, either putting the firmware on a Micro USB card and letting the radio find and install it, or a more complex process using an updater on a computer connected to the USB port emulating a serial device. Zhiwhis didn’t tell me how, but Raddy does.

This update process uses the card, so I freshly formatted the MicroSD card as FAT32 and copied the ZWS-C919.upd file to it. The update process involves turning the radio on and “playing” the file as if it were a music selection. The radio flashes “00:00” for a second and then “UPd” for a few seconds more. The radio reset to default settings and the version display now shows “1 – 910”.

Is the problem fixed? For now, yes. Now I just have to find the instructions for disabling that Morse code sound every time the device is powered.

I recently bought and reviewed a portable SDR, a no-name clone of a Deepelec Malachite DeepSDR 101. While I didn’t like the radio, I liked the concept. It has the spectrum display where I can see nearby stations and compare signal strength, waterfall display, and high resolution tuning (1 Hz). My review explains how this didn’t work out in practice on the version I bought.

Genuine radios of this genre have firmware updates and improve over time. The one I bought wasn’t genuine; software is primitive, firmware upgrades don’t work, plus the hardware (MCU, RAM, filtering) are bottom of the line, and documentation is sparse.

There are, however, better, legit, licensed portable SDRs that have features like quick access to settings through the touch screen, separate knobs for volume and tuning, noise limiters, working AGC, filtering, firmware upgrades and less overload. When I looked toward buying something better, I had sticker shock, finding radical price inconsistencies, for example two Amazon sellers with one more than double the price of the other.

What You See Is What You Get

First, obviously, it is an SDR with a spectrum display of 192 kHz and a waterfall. Frequency is displayed to a precision of 1 Hz

Most radios have settings buried in menus or underneath buttons. That’s not the case here. There are only two functions off the main screen and they are a numeric keypad for entering the frequency and one for entering the date and time. There are no hidden options or settings. Perhaps that is why the Quick Start Guide just details the display and the connectors on the sides.

Surprise

The earliest projected delivery date was a week from today, but there it was in my mailbox. It arrived in a plain cardboard box that opened up to reveal:

After weather delays, my shiny new red Sunflash RD-666 receiver / music player is finally in my hands. I bought it at TEMU for $14.73, delivered. Woo hoo!

This is a semi-blind experiment, to try something new after bypassing the new Tecsun PL-520 and MLite-880 SDR. The price from Banggood is $72.99 including shipping, plus tax. They’re also available on Amazon for (gasp) $150 plus tax.

There’s been quite a stir with questions on social media about a new radio model from Tecsun, the PL-520. At first glance, it looks like a PL-330 with rounder corners, gray instead of black.