I got lucky with mine... I paid $125 Canadian on sale on Amazon. I did the ground jumper on it and set the PA Bias in the settings and it works very well. I have gotten great signal reports up to 7000km away. I had zero expectations it was going to even turn on let alone receive and transmit. I have it with me in a case in my truck so I can do portable anytime. I teamed it up with the cheap ATU-100 auto tuner.

STOP BUYING CHINESE JUNK..... BUY DL2MAN'S VERSION... NO HE CAN NOT BE RE-SOLD...STOP BUYING CHINESE RADIOS...

That header you soldered the capacitor to is the Arduino style ISP connector for upgrading the software (edit: but it sounds like you found out later it's not the right place to solder the cap)

He should get a mic so we can hear him!

Thank you Tom for a very good video. I fixed the grounding issue with a piece of copper wire from the bnc to the chassi screws, and it made a big difference - no more static instability and also better (clearer) on receive.

Tom, Thanks for the research and information. I dont expect this unit to perform like a Icom IC-705 or an Elecraft Kx3 but for the money (fixed income here) and for a portable QRP CW rig it should work OK. Did the grounding thing and added the 100K resistor and the TX audio did improve however the cap on the header reduced the power output to 1 watt or less. This was bought from Ebay as an new but open box unit with no internal battery. I think it is the latest rev board. I would like to replace the encoder as it jumps when you press it in as if you turned it one notch up or down. would you know the part number or where I can get a better replacement? Thanks again for taking the time to share your information with us less gifted but radio afflicted hams.

thanks for the video. I have now bought 4 of these radio and tried to get them to work with no luck. I am only decent at software so the firmware update sadly didn't help. At least I was able to send them back for a refund. Now i am close to my wits end with what to do to improve this. I am not an electronics engineer, i'm an IT guy so i can't do much. As for the original creator I would love to support him but his version is lacking a lot of the stuff that the chinese sellers have added to it. The thick metal case, the integrated battery and most importantly no soldering or hardware work to speak off. This is where i think a lot of the ham projects / products out there are lacking. They are built to the old school mindset of the operator can soldering, has eletronics experiences, understandings how these things work internally so they release small kits which are hard for an average non eletronics person to use. Then Chinese sellers see these products, see the gap in the market so they take the existing designs and sell them cheaply en masse. The advantage here is that you get more people in the hobby and hopefully help to reduce the age of your average operator Unfortunately, the problem here seems to be miscommunication / mindset. If we got together with aliexpress seller and directly approved a handful of them to manufacture ready made hardware which has been quality controlled and approved then we could all win.

I have a USDX white buttons it works great as a receiver you know AM and SSB but the SSB transmit audio quality is unintelligible. I've tried changing microphones, modifying the PA bias min, max, noise gate, TX drive and still SSB transmit is unintelligible. I've read that updating the firmware to the latest version helps SSB transmit audio quality so I ordered the Arduino Uno and the cables... we'll see if the transmit audio quality improves. I may have to program the SDR radio myself to make the transmit audio quality sound good, other comments underneath this video indicate that the SSB transmit signal is not true SSB or that changes in the circuitry are emulated in the SDR....well I'm going to look at the firmware code....i think you can modify the digital filter design coefficients and the like....oh one last thing...the output amplifier is Class E meaning that it attempts to reconstruct the output RF signal using switching, sort of like how switching power supplies construct DC output by filtering the output of a square wave.

Would you please show, with better light, the fix you did on the speaker jack on the rear panel? I would like to do that as well but need a clearer picture. Are they just jumpers from one side to the other? Also, is there another value of capacitor I can use for the processor fix? I can't find any 47nf disc ceramic caps anywhere, not even DigiKey. Thanks, Tom. Doug VE7DRF

Thank You Tom! Awesome videos!! 👍👍👍

I bought one of these a couple weeks ago, and I made sure to buy it on Amazon instead of any of the dealers on AliExpress. It cost me a little more this way (I paid $132 from Amazon), but I'm glad I did, because now I can RETURN it. The radio I got is basically deaf - it can hear noise, but nothing else. Not WWV, not ANYTHING on 20 or 40 meters. And no, I'm not going to spend 40 hours on trying to make it work, because I am convinced that both the uSDX+ AND Manuel's (tr)uSDX are junk. Not just bad construction (although this may be worse on the uSDX+), but by design. I actually bought the (tr)uSDX first, from the approved vendor on Amazon, but apparently I didn't read enough reviews first, because i was disappointed in its performance. Guido, who wrote the firmware for all of these radios,, started off by modifying a QRP Labs QCX transceiver, which is a CW-only radio. He replaced most of the components in the receiver circuit that were doing an image-rejecting detector, which includes among other things, several op-amps and associated resistors and caps to shift the phase of the demodulated signal so that the undesired image signal gets canceled. This Guido replaced with code, doing the phase shift in the firmware. But he went way further than that, cleverly finding a way to produce SSB modulation without adding a lot of circuitry - again, he does this in software. I won't go into detail, but he takes the mic input, which goes through that phase shift network, and does a little more math on it to convert it from an I/Q signal to separate phase and amplitude signals. The phase he deals with by doing real-time small adjustments to the frequency of the Si5351A synthesizer chip, and the amplitude he fed to a transistor that was being used on the QCX radio to amplitude-modulate the keyer signal so that the rise and fall times of the RF aren't so sharp that they cause unpleasant key clicks. Which apparently worked all right, BUT, after some testing, he determined that the amplitude modulation isn't completely necessary - if you disconnect it, you get what sounds like highly-compressed audio, because that's pretty much what it is. And then he doubled-down on this, claiming that disabling the amplitude modulation actually improves the readability of your signal when it's down in the noise. Which of course is true, but it's not something I want to have disabled all of the time. Well, too bad, because he actually removed that circuit from the (tr)uSDX design. It LOOKS like he may be doing a slight amount of amplitude modulation by changing the DC bias on the FET gates (that circuit that you showed that had the missing 100 kohm resistor), but it's not nearly as effective. I even read one review that says that unlike TRUE single-sideband, where you only produce RF when you are talking, this radio puts out the same amount of power whether you're talking or not! I found this unacceptable, but I thought that maybe I could just add that proper modulation circuit back to the radio, and modify the code to make it work like it did in the earlier versions. So I looked on Manuel's forum to see if I could get the source code so I could fiddle with it and make it more like REAL SSB. I found a post where someone had asked essentially what I was going to ask, but he asked instead if he could use the source code from the uSDX project on the (tr)uSDX. Manuel chewed him out, accusing him of "software rape". Literally. I wrote to Manual, telling him how inappropriate this was, and also that I have no use for the firmware if I can't modify it for my own purposes. This IS amateur radio we're talking about, not commercial radios. But no, he chewed me out as well. So I thought, okay fine: I'll buy one of those Chinese uSDX radios, because at least then I would have the amplitude modulator circuit. Well, that turned out not to be the case; the design that got ripped off and built by several different Chinese manufacturers uses a later version that also does not have the amplitude modulator. And besides, as I mentioned at the start, the receiver is pretty much useless as well. So here I am with two useless radios, but at least one of them (the uSDX+) I can return. The (tr)uSDX I bought in kit form, and at least it works, but I'm probably never going to use it because I WON'T use it in its present form because what it produces is not SSB, but more importantly, I can't modify the code to make it work with a proper modulator because Manuel believes it's HIS radio, not mine. Not at all happy, and now I'm working on re-designing the whole rig because it's such a hack job to begin with. That is, starting over from scratch using a microcontroller that's up to the task.

rest easy you most probably did not blow it up. there is a problem in the design. You have a better shot of winning the lottery than getting one that is good and not need to be McGyvered

Are there mar mod for this... I can to tx on 6675 MHZ ????

Tom's Workshop, Here is a link to a video you may or may not have seen yet, I found it very informative of the USDX design... kzbin.info/www/bejne/i6eYqZqOa7Kth7c Thank You...

Mars mod for this...

I just got my usdx+ and it has no reception on all bands. I am using long wire antenna. Compared with tecsun pl330 and the same antenna, reception is very good on this little reciever. Has someone had this issue? I did a fix with connecting the ground to the case only. Did not solder the resistor and capacitor yet.

Sometimes an added amplifier will have spurious signals, these unwanted spurs being to sent to a tuned antenna, and that can create high SWR..

I bought on sometime ago, and promptly forgot it ! Decided I needed a small tuner, and luckily, or not (?) remembered where I left it ! Plugged it into a charger, and so far nothing ? Thought it might at least light up, but nothing so far ! Waiting for the Two hour charge cycle as described here, fingers crossed ! Are the only indicators for charging, when you switch the unit on ? I scanned the QR code on a card that came with it, but says in it's no longer available ? So Zero instructions, etc. ! Any help appreciated ! Thanks in advance !

I have one of those Rigs it came with no Arial can you tell me where I can get one love your Vidios

Yes, I can see were you coming from. The Chinese copy only good designs. It is the enthusiasm of people having a problem and doing research and development and come up with a new product. A good engineer needs this ability of having fun in understanding things and a child like attitude to improve it. Ones in the process you can't stop, you have to go on. Unfortunately in our world everything gets messured in the equivalent of a value of money. A good engineer is not necessary a good salesman. I can understand, I am also an engineer. Can I raise a question? The radio amateur is more and more a consumer. There is a whole industry trying to sell stuff to hams. This is a very sad development. For many years every radio amateur was a developer and researcher. Today he is a consumer with the industry getting more and more power over hams. We are on a point now where you buy a "black box" without documentation. You buy it like a can of beverage and recycle it after use.

Так этот шунт нужно будет удалить?

I heard the Baofeng Microphone works on this radio. Is it a better mic as far as audio quality?

Dis the microphone capacitor mod, but used a female header so I can remove it. For the antenna socket grounding I used adhesive copper tape.

Politics and credit mongering are alive and well in a hobby intended to share openly....build your own and settle the argumant!

I ordered the PA50+ online, and they sent me one of these. Granted it was a great price, and now I know why. The one I got does look different than the one you have shown. They have added 3 large resistors to the board, 2 of them are 420 ohm, one is 120 ohm, so I wonder if they have tried to fix the input VSWR issue. I couldn't get a chance to test it as once I applied power, the power light came on for a brief microsecond, then something in the amp shorted out, so I started a return.

Hi. I take today the usdx+ v2 and the amplifier. I want use with atu-100 like you but not tuning. Needs 10w and up. When i use the ldg z100 tuning (i listen rele and green led show tuning) but the bridge say 7-8:1. Any idea?

i have bought the usdx+ V2 and the ogs-50 and i have the at-100 tuner. on the usdx I connect the ogs-50 and then the tuner. correctly? how can i tune without transmit 50 watts to tuner? can i add a switch to the amp to turn it off when tuning?

Hi & thanks Tom, If I understand correctly the maker or designer of the amp did not allow the input side on the amp to appear as a 50 ohm load to the source radio, correct? Because I did not open the case yet I just want to be clear about where I connect the pair of parallel resistors. I saw the proper location on the relay so I am good on that. I believe you said for the other the ground tab of the two BNC connectors, correct? I guess the two connectors share a common ground tab, but as long as the connection is made to what the connectors ground to should be fine, correct? Also, how critical are the 200 ohm in parallel =100 ohm 6 watt resistor assembly values? I'll probably have to order them anyway since 3 watt resistors are not typically in my build box and I am wondering if it was just a workable value you had and perhaps there is an even better selection. Thanks again....

I bought one too. I also like it. I was aware of it not having reflected power protection, so I am only using it on a resonate 40 meter inverted V in NVIS configuration that also has very low SWR on the 15 meter band. At the moment I am using it with either a bitX-40 or early ubitX. Each does not have adjustable power so I power the transceivers with 9 volts at 2 amps max that allows the rigs to output about 0.8 watts of signal which combined with the amp becomes about 28 to 30 watts. So far no issues. I suspect but don't want to push my luck that my low input allows for a little bit worse than 1.5 SWR for maximum SWR. The only thing I noticed is the relay that switches from receive to transmit has a lag of about 200 miliseconds. I only use SSB so to avoid being initially cut off I tap the mic or otherwise spoof the start of audio. I will take a look at your SWR protection video.... 73 from kc2wvb

Great video Tom on making the usdx a better radio. I know you didn't want to get into the firmware update, probably because of added issues after updating it. Is it worth to doing a firmware update or just leaving it the way it is? If so, which firmware update do you recommend? Thanks, Martin.

It was open source. No violation. Also you bought a second version of this radio which was known to be bad. The original company had stopped making these. You should have done your homework before buying it. I own two of the original versions of this radio and have worked all over the world with fine audio reports.

The toroids for the 15m and 10m filters should yellow core.

Great job Tom you safe my amplifier jejejejej thanks

Hi sir. How are you can i ask about two meter linear what is best tube type or mosfet thanks 73

Dont you just talk, it can't help,, instead do some conserning to. Its uses, on how to bypass or tune the SWR..

Nice one Tom. Will look out for one at that price.

Mine never worked right. I have no interest in fixing it. I ordered something that should work better and not break so easy.

Спасибо Том! Очень полезные советы!) Удачи 73)

Open source is not intellectual piracy

i just got one of these, after watching your video i decided to tear it apart and lo and behold i'm also missing that resistor! I've only ever done through hole soldering so i guess it's time to learn smd. I haven't noticed any issues with grounding like you mentioned although mine is in the same anodized case. i might still do what you did just in case and ground the sleeve to a screw. the one problem i've noticed so far is that when in cw mode, my sdr dongle picks up tones from the uSDX. Both devices are sharing a single antenna and i'm not sure if that is causing abnormal behaviour but since i have yet to get my technicians license i'm quite nervous about accidentally transmitting. i guess the only thing to do is run some tests with an oscilloscope and see if it's acting up and then consider returning it and getting the trusdx if i can't resolve the issue.

Do you know what watt rating the SMD resistor should be that goes under the speaker? 73

I have one of these, but didn't realize it was a clone until I had purchased it. It is basically ok for what I paid, but if I had it to do over again, I would buy the real thing. In fact, I probably will purchase one of his soon. Manual is a great guy and deserves the money. Thanks for your time invested. BTW, do you have the firmware link?

Pleased that you found the 4.00d firmware useful. C24 is on the MOSI line, which is the microphone ADC input, so yes it is the RFI filter, given that the external microphone lead is unshielded and acts as an antenna. It is also the data input for programming so C24 distorts the data and easily bricks the atmega. uSDX was an open project with many contributors, the license does not prevent commercial use, (tr)usdx was a version where the uSDX design was used but modified, and the firmware closed. The (tr)usdx kit was sold and currently licence keys are provided, as far as I understand, to several "approved" Chinese makers, so take what you've been told with a large pinch of commercial self interest lol

Keep the vids coming Tom! I really appreciate your support on this rig! I added your improvements, and it has made a difference. I’ve had a lot of fun so far, making many cw and ssb contacts at very low power. I think the best I’ve seen, is 3.5w on 40m and maybe 20m. I love to tinker, but need a little direction. Thanks again!

So I did the mod and it sure made a real difference in the swr presented to the radio. So far I only tested with an usdx and the reports were bad, to say it mildly. I dont think the usdx is anywhere near a finished product, and thus it does not like this amp it seems. I could test the PA with my 817, but the risk and the pain involved in renewing finals on the sweet little Yaesu makes me a bit reluctant to mate these two. Maybe I am overcautious... I dont have deep experience with practical electronics but is there any way this amp could be put to work? Any bands with less unwanted emissions? 10-15-20 meters maybe ? Simple filters?

I've just seen the uSDX_ATU for sale for 185, which is the transceiver and atu all in one. I wonder how long before they add an amp?🤔

Great video Tom. Lots of true words spoken. I bought one of these and it arrived last week, already I wish I had bought the tru version. I think I have the same instability problem you experienced and was putting it down to a noisy BNC connector, so at least I now have a head start. Mine seems to work well on 20 and 15 but 40 and 80 have some sort of problem on receive that sounds like the recovered audio is being restricted by around 75%. I will start pulling it to bits soon and if I find a solution will post. I am intending to buy another, but for sure it will be a Tru sdx this time. Thanks again. Subscribed. 73s Shane. G7EWL

Funny thing, I got mine yesterday. I did some quick test on dummy load and quess what - mine produces 90-95W from circa 6W input. Any ideas? Regards

Appreciate the video! However, I set up several jigs with two samples of this amplifier, and loaded it with both tuned antenna and dummy loads, and measured the VSWR on the exciter (a (tr)usdx) on all bands, with the OGS either powered on or off. Worst case was on 80 meters, and was approximately 1.5. Best measurement was on 11 meters (no surprise). I could not repeat your observation. Can you display the actual test setup you used? Also, I would be very uncomfortable using this amplifier without some filtering. It is sending large spikes at the second harmonic, on all frequencies measured, making it unacceptable as an out of the box amplifier, even for 11 meter operation. Wonder if the manufacturer has something to do with the problem: different stores in China have wildly different pieces with the same name. Not doubting your findings! Just want to know what accounts for your findings. Again, thanks for all you do.

Tks for the tip, but I think I heard two resistors and I see four resistors, is there another modification ?