Talking about this Chinese ham radio transceiver requires a veritable flurry of acronyms: HF, SSB, QRP, and SDR to start with. [Paul] does a nice job of unboxing the rig and checking it out. The radio is a clone of a German project and provides a low-power radio with a rechargeable battery. You can see his video about the gear below.
SSB is an odd choice for low power operation, although we wonder if you couldn’t feed digital data in using a mode like PSK31 that has good performance at low power. There are several variations of the radio available and they cost generally less than $200 — sometimes quite a bit less.
There isn’t much on the front of the radio. There are a few buttons, a rotary encoder, and an LCD along with a speaker and microphone built-in. There are ports for power to run the radio if you want to not use the battery and a separate port for battery charging. There are also ports for a key, external microphone and speakers, and audio connections that look like they’d work for digital modes. According to commenters, the radio doesn’t have an internal charging circuit, so you have to be careful what you plug into the charging port.
Looking inside, the radio looks surprisingly well made. Towards the end of the video, you can see the radio make some contacts, too. Looks like fun. This is a bit pricey for [Dan Maloney’s] $50 Ham series, but not by much. You might borrow an antenna idea from him, at least. If you prefer something more analog, grab seven transistors and build this SSB transceiver.
nice, but i need digital too.
TNC2 or(and) usb for linux raspbery pi zero etc.
Mine broke down soon as it arrived. Had to send it back to get a full refund. Don’t bother.
These radios are cheap, howevet thay do tespond to CAT control, and work with FlDigi, FTS8, and JS8.
How please?
I would like to internalize the data modem with a compact display on the Chinese unit and integrate the components from this site from the original designer.
Thanks. Andrew Nz
This is very sad to see. The chinese “uSDX” is bad knock-off of community-developed uSDX transceiver, mainly knock-off of “uSDX Sandwich” developed by Manuel DL2MAN. His design is under 50 EUR btw.
It’s sad to see how Chinese copies have gained fame and the original, developed by the authors who did the main work, remains in the background.
See http://www.dl2man.de and https://groups.io/g/ucx
Hi, thanks for the links. The price is really nice and I’m tempted to buy one to support the developer although I don’t have a HAM license and I’d be interested only in receiving the entire HF spectrum in all analog modes.
Another “toy” I’m considering is the Belka-DX receiver which got stellar reviews around, but costs more, although still at a very reasonable price given the features: https://belrig.by/belka%20dx%20with%20speaker%20EN
Interesting. I wonder how clean the output is? Inadequate filtering has been a problem in some Chinese transmitters (Baofeng, I’m looking at you here)
buy woxun, this firm are better but still cheapest
in my opinion TNC (APRS etc) will be great
There are several chinese rip-offs of the uSDX project. I don’t know for sure if this applies to all of them, but spurious emissions are awfully high from some of them.
The reason is that when the Chinese copied Manuel’s original design, they used different PA transistors but copied the filter values. And since filters are essential in a Class-E amplifier, the result is poor amplifier efficiency and strong spurious emissions.
Unwanted harmonics appear to be a problem at 20 MHz and higher frequencies, as demonstrated by DL2MAN (the creator of this design, that this is a copy of) :
https://youtu.be/Q1bTomgTMhQ
It looks like the output is clean enough on the 80m and 40m bands.
The issue seems to be the use of cheaper transistors in the Class D amplifier stage, that are less suitable for the higher frequencies.
Yes, true. It does need more filtering on 15 meters on up (down?). But one must admit, this is a clever design.
This is indeed a nifty radio. However, it’s totally ripped off DL2MAN’s uSDX design, with no credit (and bad component selection: the radio is supposed to be highly efficient, however the cloners didn’t use the right final transistor and efficiency drops to around 50%).
The actual kit costs around $50 when assembled, so I’ll let you imagine the margin those cloners get…
Here’s the original design: https://dl2man.de/
They used the IRF510. That’s the transistor used in the BitX. It has a lot of history with QRP rigs.
True, it does (I’m also using it on my “Puzzle” project, shameless plug here: https://hackaday.io/project/20067-puzzle-radio-building-blocks ).
But If I’m not mistaken, the uSDX has been tuned specifically for the IRLML2060. Simply replacing it with an IRF510 won’t yield the same efficiency…
The IRLML2060 is $0.46 in onesies from Digikey. It had to be a supply rather than cost issue! In any case, thanks to Mano for the heads-up on the original designer’s website. I’ll be buying from him, since the Chinese effort seems to have several shortcomings.
Sad that ppl don’t even want to pay $50 for the original kit. I think it is relatively cheap compared to commercial available products. Wonder if the open source movement is going to be a thing of the past when those cheap clones keep popping up. Just shaking my head, good times with all info to learn about electronics will be over soon. Hope I’m wrong.
Exactly right. The uSDX uses a class E power amplifier that is modulated using innovative software to generate the output waveform, and like all class E amplifers, the output matching network must be designed for a specific output device (refer to many publications from N. Sokol, D. Cripe and others). Some cloners substituted an IRF510 which has very different characteristics that prevent it from operating class E above about 10 MHz without even attempting to redesign the output network. As a result the efficiency and power output are far less with their substitute “launch tubes” (as the eBay description called them). The uSDX project is a fascinating example of how to obtain amazing results from an 8 bit MCU and minimalist hardware, but “buyer beware” should absolutely apply. The ucx@groups.io discussion group is the best place to learn about the design and history as all these issues have been discussed at great length.
Waiting for these radios to add a wireless control/data interface (WiFi or BLE). Like the HG-UV98 but more comprehensive.
If it’s a clone of an open source design then it can’t be that hard to add such a feature. Maybe after doing so you can get your writeup posted here on HaD!
Oh, hey, I should have watched the video before posting. There’s a UART connection. How about a little dongle to plug into that. Piece of cake!
You have to be careful when adding digital to these simple voice qrp transmitter designs. Digital modes are usually 100% duty cycle where voice is much less. You might have to cut back the power in order to not overheat it.
OTOH, you might not need much power for weak signal modes so it is do-able, just watch the temp on the finals.
Not sure why you think SSB is an odd choice. Not only is it the standard voice mode for hams, you can run most digital modes over it via computer sound card…
“Because other modes will get out better”.
Ten-Tec started as a QRP company, with CW, but within a few years had SSB transceivers.
There’s that Yaesu rig, up to 432MHz, that’s QRP.
Wow, that’s quite a battery!
I’m glad to see these getting cheaper. I’m too broke to try out HF otherwise.
QUESTION FOR ALL OF YOU FELLOW HAMS:
Speaking of the proliferation of kits, and other low price transceivers – I WANT TO FIND A VERY AFFORDABLE 2 METER CW RIG. I WOULD EVEN SETTLE FOR A LITTLE AVAILABLE QRP’er THAT COULD EASILY BE MODIFIED TO OPERATE ON CW. (Not MCW.)
I have been a 2 meter fan since way back when I was a young sailor in the USN. A fellow sailor was kind enough to get me started in ham radio, and helped me choose a Heathkit 2 meter regenerative xcvr as my first rig. It was lovingly called a lunch box. Since that more than humble beginning, I have been interested in 2 meters, and, since then, I have been a fan of CW. No, the lunch box was not capable of CW, just AM, but I banged out CW every day for the Navy, and came to love it. well, since I got back into ham radio about a decade ago, I have always wanted to combine my loves for CW and 2 meters. Sure, I have found a couple ancient, or crazy expensive newer rigs that are capable of it, but I want to find a very affordable 2 meter CW rig. Like I say, I would even settle for a little QRP’er rig that I could easily modify. Of course, you say, “Don’t waste your time, nobody is on CW on 2 meters to talk to.” Well, that’s true, but here is the idea. If I could find a cheap little rig, I would even be willing to give a few away to hams in my area, just to seed the idea… I live in an area of big hills, located between Seattle and Mount Rainier, and surrounded by a bunch of towns, so there is no shortage of hams around me. I don’t currently have a 2 Meter rig of any kind, and I am holding out on getting one until I find that cheepie that I can use to seed the idea of 2 meter CW.
IF YOU HAVE ANY IDEAS TO HELP ME ON THIS QUEST, I WOULD BE VERY GRATEFUL FOR HEARING THEM!!!
THANKS, BILL W, N7TIT
Build it. There’s 70 years of 2M transmitters described in the magazines, from tube to transistor. Once you have a transmitter, adding CW is easy.
But you’ll need a receiver. The usual route used to be a converter into a shortwave receiver, make sure it does CW.
People would take commercial FM transmitter strips and add a key jack. Sime even did it with 2M FM transistor rigs.
You’ll need a suitable crystal, maybe build a VFO VXO.
Choices are extremely.limited until you look at all that’s come before.
the G-QRP club certainly has a few 2m CW qrp rigs in their archive of sprat magazines, I think you can order a copy of their entire archive on a USB stick from the gqrp website http://www.gqrp.com/
Why is HaD pimping a ripped off radio? Isn’t this DL2MAN’s design?
please take this article down, you are portraying a chinese rip off that stole guido and manuel’s work in a positive light. If you want to feature something feature the amazing work Guido and Manuel have done. reach out to them, they would be glad to assist with an article i think.
It’s really sad to see, How the chinese have blantantly copied Maneul & Guido work.
https://itshamradio.com/usdx-forked-out-to-trusdx/
https://itshamradio.com/top-6-reasons-to-avoid-chinese-usdr/
I think updating the article with this new information would be appropriate!