Wouxun KG-UV920R volume mod

There aren’t many HAM operators yet who own the Wouxun KG-UV920R, but the first mods already surfaced. This one is might be interesting for people who want to use the radio in the shack. As is often the case with first runs of Chinese equipment, the lowest volume level isn’t really low. I didn’t regard this to be a problem for a mobile radio, and didn’t mention it in my review. Thanks to the efforts of VA3ISP Wouxun came up with a fix.

No details on the original resistor values, nor on the best replacement values, so you’ll have to figure it out yourself.

KG-UV920R Volume Mod. Click for large size.

Review Wouxun KG-UV920R

Note: this model has been replaced by the KG-UV920P.  See here and here.

The long (very long!) awaited KG-UV920R finally hit the stores. I was able to get hold of a review sample, which was kindly supplied by Bamiporto.nl. This is the European version, which means that TX frequency range is limited to EU amateur bands, e.g. 144MHz – 146MHz and 430MHz – 440MHz. After a week of clinical stuff (measurements) and a few days of real life playtime, I decided that it was time to put some things on paper, make a few pictures and dump spectrum analyzer images onto a USB stick.

What’s in a name?
There are ham operators who will only buy one brand and defend it in such a way that Apple fanatics suddenly look reasonable. Personally I don’t care much about brand names; almost every respectable brand has found a place in my shack. I admit, lately I’ve been very, very cynical about this Wouxun. Too cynical probably, but not without reasons. Communication with Wouxun stalled, initial specifications vaporized, and the final price level ended up way higher than any of us expected. Yet every radio deserves an honest review, so here we go.

Organized chaos in the shack while working on the KG-UV920R.

Wouxun KG-UV920R inside. Note the empty spaces next to the stock filters. Room for optional ones? The large empty space is presumably where the optional scrambler goes.

Look & Feel
If looks were the most important factor, I would have fallen in love instantly. This radio looks good! There are hard-to-miss signs that the engineers did some serious thinking here. The front panel is detachable and can be mounted under two different angles: slightly upwards and straight. The latter is what we’re used to and the best option when the radio is mounted under a shelf. When mounted under a car dash, the tilt option will be great. Completely separating the front panel from the actual transceiver is possible too, and a long extension cable (RJ45 on both sides) is part of the package. Front panel on top of the dash, transceiver in the boot.

There are two speakers built in, one for each VFO. Interestingly, they’re not the same size. Two external speakers can be connected at the back, and you might want to give this some thought. Depending on the stations listened to and the volume level, the internal speaker set resonated a bit at times.

When the separation kit is used, both internal and external speakers become either unusable or impractical. That’s why Wouxun added a third speaker, which is located at the back of the microphone. Switching from one speaker system to another can be done from the menu. Keeping them all working simultaneously is possible too.

The antenna connector is SO-239, which is surprising. For obvious reasons I would have preferred to see an N-connector here, but I’m pretty sure some users will love it – quite a few people seem to have eternal troubles when assembling N-connectors and revert to using PL to N adapters. Please don’t, read this instead.

Buttons & Knobs
Wouxun did their best to squeeze as much ‘direct access’ buttons on the front panel as possible. I can’t fault their arrangement, but the buttons are on the small side. This has implications for the readability of the typeface used to describe the various functions. Even with good eyes it’s hard to read what all those buttons do, so memorizing their function is a good idea. Three rotary knobs take care of frequency and audio levels.  Most functions can also be accessed from the microphone, and to prevent accidental changes a ‘lock’ switch is added.

Less bloated, better specs
Wide band receive died during the design process, which saves me a lot of time. Although many potential buyers were specifically interested in this feature, including me, there was a possible downside. Front ends in such ‘I can do it all’ radios tend to be rather poor and can turn a ham’s life into hell. A good example of a poor front end can be found in the Kenwood TMV-71, a radio which (more or less) can’t receive anything under S9 in RF polluted areas. Unfortunately I live in such an area. On the bright side: this QTH is an excellent testing ground for receivers. I could only hope that the Wouxun engineers put some work in designing a good front end. Well, they did.

Receiver
The KG-UV920R is very sensitive, no doubt about that. On 145.000MHz  the radio came to life at -128dBm, which is as good as it gets. On 435.000MHz a signal of -125dBm was needed to replace noise by a signal. Sensitivity is generally better on VHF than UHF on most radios, so no surprises here.

Selectivity is better than most of my other radios – both the Kenwood TMV-71 and Alinco DR-635 had to bow to their new master. In situations were a certain amount of splatter was normal, the Wouxun kept its head cool. Only my Yaesu FT-8900R can match this, as well as the FT-7800/7900 series. All the strong out-of band signals present here were handled surprisingly well, and enabled me to hear a distant 70cm repeater which I haven’t heard in years. Wow.

Transmitter
If you like radios with sufficient power output, the Wouxun KG-UV920R will neither disappoint nor excite you. Measurements done at 145.000 MHz and 435.000 MHz respectively.

VHF Low: 5.3 Watts, Mid: 28.0 Watts, High: 49.5 Watts
UHF Low: 4.1 Watts, Mid: 25.2 Watts, High: 34.1 Watts

TX audio is fine; listeners noted that there’s an emphasis on the higher parts of the audio spectrum. No distortion to report.

Harmonic Suppression
This is the one area where I didn’t expect to encounter problems, but did. Not as dramatic as the Baofeng UV-3R, but Wouxun should really have a look at this. They can do much better.

Second harmonic, VHF, ± 47dB down. Disappointing.

Third harmonic, VHF, ± 54dB down. Not good.

Second harmonic, UHF, ± 58dB down. OK. Third harmonic undetectable.

Other noteworthy features
– Cross-band repeat. Works as advertised, no issues.
– Compander. An interesting system which limits RX noise, and enhances TX audio (compressor) for long distance QSO’s.
– Nice FM radio.
– Scan. Finally a scan system with a sufficient scanning speed.
– Optional scrambler. Illegal for HAM use, but could be interesting in other fields of communication.

Bugs
Changing frequency or volume is done by rotary encoders instead of mechanical switches and pots. In theory this system has a lot of advantages, such as precision and lack of crackling noises caused by wear and tear. Unfortunately the encoders used in the KG-UV920R aren’t always responding properly. Sometimes they go wild when adjusting the volume, sometimes changing the frequency just doesn’t work, or works the other way around. Very annoying. After checking with Ruud from Bamiporto.nl, it seems that it’s not just a problem with my review sample. Ruud will inform Wouxun about my findings.

* Small addition: just before I  wanted to repack the radio, I noticed that there’s another problem when using the rotary encoders. When changing the frequency on one VFO, audio on the other VFO mutes for a while. No other radio I know does this.

The verdict
The good: user friendly design, excellent receiver, good audio on both RX and TX.
The bad: Harmonic suppression disappointing. Rotary encoders are unreliable.

Bottom line: this radio still needs some work. The KG-UV920R isn’t a bad radio, but for €299.00 I expect it to be as good as the competition. That’s not the case – yet. If the described problems are solved, I wouldn’t hesitate to buy one.

Wouxun KG-UV920R Alternatives

If you’re also shocked by the the feature list which imploded about as fast as the Greek economy, plus the worse-than-Venezuela’s-inflation-rate price hike of the Wouxun KG-UV920R, check Brick O’Lore’s post on the Baojie BJ-UV55 aka HYS TC-UV55. The menu system looks a bit like the one we know from the Baofeng UV-5R, and the microphone is an exact copy of the one we know from Kenwood. No x-band repeat though, not even an internal speaker, no cooling fan (hmmmm), and an SO-239 connector instead of N (hmmmmm again), but the radio is at least $100 cheaper.