The Zhiwhis ZWS-C919 is a device that receives a wide range of frequencies and has a long list of features. It scores high on quantity. This review concentrates on how well it performs all those functions it has. The firmware underlying this review is v1.723.
Overview From 10000 Feet
It’s a big radio that receives frequencies from 153 kHz to 999 MHz. Identified bands are LW, MW, SW, FM, VHF, UHF, CB and Weather, but of course the frequency span covers more services than the radio calls out; for example, GMRS tunable by channel.
One stand out feature is the speaker, one of the best. The speaker is 20W, but it appears that the actual circuit only delivers 4.6.
It’s also a very complicated radio with a daunting list of settings, particularly complex in the area of antennas. It’s really difficult to put all that information together from several sections of the manual and block diagrams.
Technology
While the Si4735-D60 chip used in this unit is FM RDS capable, the feature is not implemented. It does support SSB, but my example is not well calibrated for SSB. It’s the same chip used by the XHDATA D-808 radio, which is not well calibrated on SSB in my example either. A teardown found that the audio output stage is identical to the HanRongDa HRD-A320 and that the output capacity is measured as 4.6W.
Those in the know have commented that this radio looks like it was designed by an engineer. That makes sense, and perhaps explains why it is as complicated as it is, particularly in the area of antennas, and why it’s so daunting to the end user.
What I’m starting to notice is similarities to other radios I have.
The first similarity is a tuning rate indicator that is a mark about the digit that’s being changed when a knob is turned. My HanRongDa HRD-701 has it and my Raddy RF760 too. The C919 implements it a big more transparently, switching the digit to increment by pressing the fine tuning contr0l knob. I call it “fine tuning” out of habit, but the manual more accurately describes it as the “inner knob.” The outer knob can be finer in frequency increment than then inner.
Features
This is a collection of things the radio does beyond the usual stuff.
Free Radio Service / Personal Radio Service
The UHF band covers various national personal radio services, like FRS/GMRS in the US, Mexico and Canada. A setting (see manual section 24.2) can pick a service and then the radio can tune the identified channels of that service. That’s the good news. The bandwidth of regular GMRS channels is 20 kHz, but there doesn’t seem to be any way to set it wider than 4.5 kHz. More on this in Part 2.
The best I can tell, WFM is only available on the FM broadcast band.
CB?
I expected CB to work like GMRS did, with the ability to tune by channel. When I selected CB with the UHF/VHF button, the radio tuned to 25 MHz and I picked up WWV. The radio is clueless about CB frequencies (they aren’t even in the manual). The only thing special about the CB band beyond regular shortwave is that one can pick POP, ROCK, JAZZ, CLASSIC and COUNTRY equalizer settings. 😲
Having a separate AM only band for CB that doesn’t do anything special is rather silly. Exactly what is one going to store in the 200 channel presets wasted on a 46-frequency band? Plus it doesn’t support the ability to switch to NFM. The regular SW band does all the AM/SSB CB stuff and the VHF band does the NFM CB stuff.
There is one curious thing about the CB band however, it seems more sensitive to the ear. This is borne out by the specifications that say SW is 20μV, while CB is 10dBμV. Those are different units, but when converted to the same units, CB is more sensitive.
I’ll talk about this more later, but one thing I haven’t see for many years is a variable capacitor that used to be called an “antenna trimmer.” It helps balance the antenna with the radio. The Raddy manual calls it a “tuning knob” but it does not change frequencies.
Other features:
- Squelch
- ATS with 1600 preset locations, 200 per band
- App control
- Bluetooth speaker
- Computer speaker
- MP3 player (up to 256GB cards)
- MP3 recorder
- Aux input
- Computer access to memory card vis USB
- Firmware upgradeable capable
The elephant in the room:
- No flashlight
All My Antennas
The C919 has 6 antennas and 4 antenna controls! That’s a bit daunting.
First there are two built-in ferrite loop antennas, for LW/MW, and a 98 cm telescopic whip antenna. Add to that a top mounted SMA male connector for a “walkie talkie” antenna and a jack for an external loop antenna. And on top of that there is an external antenna jack on the back.
There is an on/off switch next to the external loop, a 3-position switch (MW, SW1, SW3) external antenna switch on the back, an antenna selector button and finally an antenna tuner knob. This is on top of the internal switch that disconnects the telescopic antenna when the external antenna is plugged in.
I will add my vote to that of every reviewer that has commented on the small on/off antenna switch on the top of the radio. It is cheap, ambiguously marked and feels likely to break off.
I will admit that the whole antenna business has caused me more confusion than anything else about the radio and while I’m going to advise reading the manual, the most helpful and clarifying thing doesn’t some from the block diagram, nor from the manual description of the jacks and the controls. It comes from the manual (section 7.2) description of the display. Here’s the figure:
My approach is to flip switches that seem appropriate and then look at the display screen to see what really happened. There are my notes about those icons:
- The Loop icon can refer to the internal loop or the external loop.
- The Rod icon can refer to the telescopic antenna OR the external antenna jack on the back (which automatically disconnects the telescopic when something is plugged in).
- WT. ANT. The antenna used is the Walkie Talkie jack with the SMA connector. It’s only available for UHF/VHF frequencies, including AIR and Weather.
- INTERNAL. This is on when the internal loop antenna is used for MW/LW or in the case of UHF/VHF when the walkie talkie SMA jack is used.
- AUTO. This means that the radio electronics are making the decisions, and that the options for a low pass filter, high pass filter and low noise amplifier (LNA) are possible.
- LOCAL. This reduces the antenna signal to prevent overload. It has 2 values.
- DX. This allows the antenna to perform to its maximum
- Finger Point: this means the Antenna Tuning knob on the side of the radio might help something.
- LNA: the first low noise amplifier is on.
At this point, I suggest the viewer read section 23 of the manual, but not spending too much time on the block diagram at first. Section 23 refers the user to sections 6.6 and 6.7. And just for fun, read section 8.3.10. The figure in section 6.7.2 is wrong (see later).
A MW or shortwave antenna can be plugged into the back of the radio, but not a longwave antenna; that has to be plugged into the top (so the manual says).
I at first thought how convenient it was to have an SMA connector up top that I can just cable up to my MLA-30+ antenna; however, the manual says that connector, the “WT” antenna, only works with frequencies over 30 MHz (Manual 6.7.1) .
ElectroBananas in his monumental video on this radio points out a mistake in the manual and in the separately supplied reference card. Documentation indicates that the rotating external LW/MW antenna should either be a 3.5mm mono jack or a stereo jack where the Ring and Sleeve are ground and the tip is signal. This is an illustration from the manual (6.7.2):
ElectroBananas says that the radio shorts the ring to tip, making a mono plug useless, and this wiring chart wrong. He says that only a stereo plug will work and that the ring should not be connected. The supplied loop antenna complies with his recommendation, not what is in the manual. I verified with an ohmmeter that the Tip and Ring are shorted by the radio.
And to sweeten the pot, there are switchable low noise amplifiers, antenna attenuators, low pass and high pass filters. Some work with some antennas and some do not. The radio comes with a block diagram to help sort it out:
The block diagram is purely conceptual, since a fair amount of what goes on here happens inside the Si4735-D60 chip that incorporates the LNA, PLL synthesizer, mixer, DSP demodulation and final digital to audio conversion (DAC). The radio is controlled by an AB5301A 32-bit RISC micro controller. The particular chips involved are identified in this detailed teardown video from the ElectroBananas YouTube channel, that has its own diagram based on his analysis of the circuit board. I strongly recommend this video for the technically inclined. One major takeaway is the radio is packed with electronic antenna switches, routing the signal every which way.
The user is left with the danglins question: would reception of this signal be better if I tried a different combination of settings? So try it.
Weather
Weather band works, and weather alert scanning works the way it does on many radios, long press SCAN when on the Weather band. This disables the radio for other functions until another long press of SCAN ends the mode. I found that a long walkie talkie antenna worked on this band also. Based on some unstructured testing of the radio, I would expect the weather alert to deplete the battery within 2 days.
Nit Picking the Manual
This refers to the August 1, 2024, Raddy manual. The Zhiwhis version still has the “shuttle button” to refer to the tuning knob, but I doubt any user will be using the Zhiwhis manual when the greatly expanded Raddy version is freely available.
- “Walky-talky” should be Walkie-talkie.
- Information on wiring the external antenna for MW/LW is wrong. The TIP and RING are shorted, not the RING and GND as shown in the manual.
Power
The radio uses 2 18650 batteries. I haven’t quite figured what the problem is but I tend to leave the radio on. I went to try something tonight and the batteries were dead. I have plenty of spare 18650 batteries, none of which worked because the C919 uses flat top batteries and everything else I have uses button top. So the radio is down until the batteries charge back up.
Questions
These are questions I have and when answers are found they will be added.
- Is it possible to display the firmware version? [Yes. The simplest way is to press the gear icon on the phone app. Mine is 1.723. It can also be displayed in offline setting mode by the radio.]
- Can the radio be calibrated? [Apparently not]
- Can the thermometer display degrees Fahrenheit? [Manual says it’s fixed at Centigrade]
- Does it support Weather Alerts? [Yes. Long press SCAN in Weather Mode. Long press again to exit.]
- Can the FM step be set for Region 2 (200 kHz)? [No.]
- Can it record from Bluetooth? [No]