| KA4DQJ |
Rating:  |
2024-07-09 | |
| Works with conditions. |
Time Owned: 3 to 6 months. |
I remember when the USDX V1.0 came out. Judging from what other hams were saying about this rig I passed. Then, the USDX+ (plus) V3.0 "white button" upgrade came out which some said actually worked. Always a sucker for a new toy - especially a cheap one - I picked one up from Amazon. I even spent the extra $20 for the wall-wart battery charger. The "All-Mode, All-Band" transceiver covers 80 to 10 meters except no except for 12-meters. It is also only a SSB/CW radio. The AM and FM selections appear in the menu, but don't appear to actually do anything.
When the USDX+ arrived I learned that the seller was selling chargers for an non-chargeable item... there's was no battery in the thing. Not the rig's fault but something a potential buyer wants to be aware of. The battery is said to be proprietary and isn't inexpensive. Bad too is that not a scrap of paper came with the rig. There are no instructions on how to use the thing, no manual, not even so much as a schematic. But, a battery isn't a must - the radio runs off 12v external power too.
Users report that if you set the drive and bias too high it's likely to blow the final transistors in short order. Other than the final transistors (covered below) there's nothing outside the MENU that the user can change. There's not a single hardware adjustment on the rig's single board. Most of the space is taken by the low-pass filter hardware. I've also looked high and low for a user's manual or schematic. Nada.
The rig's final amplifier consists of three parallel-wired BS170 FETS. Also parallel-wired with the finals are two vacant spaces; one for an SMT final, and one for a T220 device. I experimented with adding IRF530s and P16NF06 FETS parallel to the stock BS-170s but found no increase in RF output.
On setting the drive and bias without blowing the finals. I set the MIN bias to "0" and the MAX at "190" (MAX will go up to 255). I started at 100 and increased the bias in steps of 10 until further increases produced no higher RF 'output. That occurred at 200, so I backed down a step to 190 and left it. So far so good and I've thrashed it pretty hard at this setting. Key down CW output on 40m is exactly 4-watts. I wonder if the max setting is different for each rig? One ham on YouTube suggested a MAX of only 130, but he also sets the MIN bias at 20 whereas I use 0. The DRIVE goes from 0 to 8 and I use "5" although it's been reported that anything higher than 4 can cause audio distortion. Again, the setting could be rig-specific but 5 works for me.
So that's my updated take on this little transceiver. The USDX is said to be the "cheapest, all-mode, 8-band" rig currently on the market.
ADDENDUM JULY 9, 2024
I had to answer the front door for a pizza delivery and accidentally laid a cell phone down on the straight key. By the time I got back... you guessed it, the three BS-170 PA MOSFETS had resigned permanently.
Adding an IRF530 into its pad doesn't seem to affect RF output when it's parallel with the BS-170's, but with the BS-170's removed the big IRF530 goes to town on the RF output.
Unfortunately I forgot to lower the PA drive in the menu and the current draw burned out some circuit board traces in three spots. So I repaired those and tried again using the IRF530 - with the PA Drive turned way out I adjusted the drive for 5w key down in CW mode and will try that for a while. The only thing that might get too warm is the IRF530 itself which I think should use some sort of heat sink. |
|
| VE5EDE |
Rating: |
2024-05-26 | |
| Smallest Bundle of Joy Yet |
Time Owned: 6 to 12 months. |
Operating Manual and Data sites:
https://groups.io/g/usdx-users/message/123
https://github.com/TekMaker/uSDX-QRP-Transceiver/blob/main/uSDR%20Manual_V1.0.pdf
Having spent many years operating where there was limited electrical power, this one caught my eye. Over the years I've become addicted to QRP because I can talk to the world on a battery. Previous rigs I've employed include an HW-8 which I completed myself in 1981, an Argonaut 509, a YouKits HB-1B, a Pixie and several home engineered projects. Anyone who has experience in QRP knows SSB is a masochistic proposition, but hey, sometimes it works quite well. Otherwise CW is the way to go.
Mine is the uSDX+ from AliExpress and included a rechargable battery and a wall wart for Europe, easily adapted.
It's easy to spot the appliance operators here, because they expect to switch on a radio and get a QSL card. The uSDX+ is anything but that. It actually requires reading, research and sharing of infoirmation. This is an experimenter's radio, and likely will draw in kitbuilders and homebrewers alike while instantly shutting the rest out as they blame the radio for their own impatience and failure. Please don't fire it up and just start transmitting. Check on all settings, start slow and work your way up carefully. It's a 4 watt radio, not a QRO rig.
Alas, the originators of this kit have fallen into 21st century internet behaviour by giving us this circuit as a gift, but then whining about who owns what. Their plastic radio seems inferior next to the Chinese copy in every way. I guess that means they have earned the right to take exception. Yeah, I'm an old guy...I remember when ham radio was for the advancement of the hobby, not someone's wallet or ego.
The chief feature of this little guy is the Digital Noise Reduction. No other inexpensive radio can provide such quieting. The next feature is a full range of bandwidths to also fight QRM. These capabilities place this radio well above those I've used in the past. The listening experience can be quite comfortable once all the tweaks have been made.
The receiver doesn't quite come up to snuff compared to my 991A, but then usually my QSO's are with someone using far more power, so it evens out. And in most cases my QSO's are with folks with radios and skills that can extract my little peanut whistle from the ether. You can tell QRP excites me and I appreciate all the different types of ops who have given me nice QSO's over the years.
Numerous articles and reviews are on YouTube, and a few are even useful. The first few runs of this radio were of lower quality, but can be upgraded...not exactly a plug-and-play appliance! I'm still fiddling with mine and am happy with all settings but the drive on SSB which I need to improve upon (thanks to KA4DQJ below for his advice). I used a Baofeng speaker-mic instead of the supplied mic and it gave poor results, so I went back to the teensie one that came with the radio.
I also added a matching ATU-10-2a antenna tuner which allows it digest just about everything impedance-wise. On the run I use a 9:1 unun and an endfed. At home either a full-length 160m off-centre dipole or a T2FD, which is vastly superior.
It's not a 5 star radio in the company of the some fine appliances built today, but once it's setup, it's the best QRP experience I've had in over 48 years. "For the Money" it is 5 stars. Compared to other radios I give it 4 stars. Penny for penny, the best radio I've ever owned.
The only way you'll regret buying this is if you think it's plug-and-play. Be prepared to use your brain and you'll have great fun...73 |
|
| KC3TEC |
Rating: |
2024-04-01 | |
| Good for what you paid for it |
Time Owned: 6 to 12 months. |
While it is not compareable to a kilobuck rig or a g90
As long as you dont overdrive the audio its not bad.
1st qso ssb 20 meter was Canada, 2nd Scotland and my third France!
And im in Pennsylvania, USA
No amplifier just the transceiver and homebrew dipole.
So Ive got no complaints on this radio. |
|
| KB0TTL |
Rating: |
2023-12-28 | |
| Effective portable for backpacking and POTA. |
Time Owned: 6 to 12 months. |
Remember the old adage that the most worthless [fill in the blank] is the one that you leave sitting at home? This also applies to HF rigs when you're on the go. Business trips, weekend trips, and short day trips often don't afford you enough suitcase room to pack much of any gear at all. This is especially true if you're flying somewhere. Activating that cool out-of-state park can go from a burning desire to a reality if you have one of these little rigs in your bag. No, they aren't super powerful. No, they don't have all the features of a Yaesu FT-891. What they do have are the bare necessities in a remarkably small package size. I bought the version with the 1100mah internal battery, and this battery is enough to operate the radio for at least an hour or two on a POTA activation. Simply bring a resonant whip antenna or a shortened endfed that you've pre-tested for a good match on a few bands (and some coax), and you're ready to go. 18.5' of wire attached to a 9:1 unun is your friend in small spaces! I have successfully completed 3 POTA activations with this rig so far, and the only complaint I have is the low audio output. A good set of earbuds fixes this problem.
What this radio is good for:
POTA
SOTA
Traveling
Fun on the beach
What this radio is not recommended for:
Field day - rejection of nearby signals is not good.
Contests 1 mile of another station or within 5 miles of a strong AM station.
At minimum, you'll want a small band pass filter if you use one of these in a contest. |
|
| K6SDW |
Rating: |
2023-12-04 | |
| Basic transceiver best for CW, so so for SSB |
Time Owned: more than 12 months. |
I operate mostly CW so IMO the uSDX radio on transmit/receive is surprisingly good, not great compared to my KX3, but for around $150 I'll keep it for field use.
SSB I found a mic kit for $15 from Pacific Antenna that really improved the transmit audio. I've reviewed the mic elsewhere
The uSDX is a good choice for occasional field use like SOTA/POTA.
The unit I have has controls on top, different from photo but I believe same circuitry
GL/73 |
|
| PA4VA |
Rating: |
2023-02-23 | |
| Same issues as NB4M |
Time Owned: 0 to 3 months. |
I had the same issues as NB4M: after a few days the power output was gone. I had this with 2 different radios based on the same schematic.
I hope the problem can be found in the 3 BS170 PA fets.
Otherwise it became a receiver indeed. |
|
| KB3TVR |
Rating: |
2022-11-24 | |
| Atfer 50 QSOs, I think this is a keeper |
Time Owned: 0 to 3 months. |
I've had this little uSDR/uSDX radio from China for about a month now and I've had great success with it right out of the box (the version I have has the display on top, not on the end). I paid about $140 for it and thought it might be worth the gamble, and I'm satisfied. I'm running it through a G5RV jr. antenna in my attic and have been having no problems being heard. Of the 50+ QSOs to date, almost all are within a 1,000 mile radius (and the majority are 500 miles or less) though I did have a nice DX with an op in Cuba this week. Almost all have been CW. My typical signal report has been 559 or 569. Though it has a built-in lithium battery, I've been using an external power supply which gives the transmitter more oomph.
The down side: the user interface is clumsy and inelegant. The power goes way down on 15 and 10 meters, but that might be a factor of the attic antenna I have. Almost all the QSOs I have had have been on 20 and 40 meters.
Last remarks: I finally tested the SSB this week using the internal mic that is built in. I was heard in central Texas from my QTH near Baltimore with a report of 59 (which was probably generous on their part). Bottom line: I think this is a great little radio that is inexpensive and makes good use of the open-source software for SDRs.
|
|
| NB4M |
Rating: |
2022-09-12 | |
| QRP Bargin |
Time Owned: 0 to 3 months. |
Update: It quit after a few days. Had it stored in the box and upon the third use, no TX. Tried the reset with no success. Now I have a SDR receiver that's pretty poor in quality.
*******************************************
Recommended and would buy again.
For the price you won't find a better deal on an eight band all mode QRP rig. I can only speak for CW mode, but so far it's getting the job done. Loaded with simple menu features and a consistent 4-5 watts output. Good buy for anyone wanting to try QRP or the seasoned operator. |
|
| AA4WA |
Rating: |
2022-08-31 | |
| Red Corner version - Ok for portable CW use |
Time Owned: 0 to 3 months. |
I bought this inexpensive portable (Red Corner uSDX uSDR+) HF transceiver to replace my CW only MFJ-9200 QRP rig and I am quite satisfied with it. It has an internal battery pack that seems to last long enough to make plenty of contacts and I also use it's external power input with my 10 AA rechargeable battery pack. My primary reason for getting the uSDX unit was it's coverage from 80 to 10. The MFJ-9200 did not have 12 or 10 meter modules as an option and 10 meters is important to me. Although results may vary between the many different versions of the Chinese uSDX, my unit has a nice 4 watts CW output on 10 meters and up to 7 or 8 watts on some of the lower bands.
Reception isn't bad, once you get the hang of using the various ATT settings. You really need to add db ATT on the lower bands, even up to 20 and 17 meters sometimes. There are different AGC settings, but I just keep mine on FAST. There is an AGC behaviour just by the fact that this is an inexpensive SDR type of radio. When you make a change or move to another band, be patient and allow the internal processing to catch up. You also need to utilize the Volume control (shortcut is to press the tuning knob and turn) and adjust it high enough to be able to receive signals, but not too high or it can squeal and make more noise than necessary. For my CW operation I always use earphones. It's also good to have some sort of external volume control on the earphones to allow the radio's volume to be up enough to work properly, but still not blast your ears out. With practice you can find a good setting to get the radio to receive quite well. The problem I had with the MFJ-9200, was that it only had one ATT position if you needed to reduce too much input signal. The uSDR has 2 ATT options. The ATT 1 seems to be the standard input attenuation and the ATT 2 seems to be sort of an I/F attenuation. I mostly use the various ATT 1 settings, but sometimes if I need to knock the gain down just a little bit more, I will move the ATT 2 up to the 1 or 2 position.
I also like that you can change the CW band filter to several different settings and since I tend to operate on less occupied bands, I like to leave it on the 1800 hz position. I'll move it to 500 hz, if things get crowded.
I have been very pleased with using this radio for CW portable. Power draw, even with 5 - 7 watts out is mindblowingly small, less than 2 amps on transmit and receive doesn't even move the needle on my power supply amp meter, although they say its 70 ma. The MFJ-9200 was 40ma on receive, so that's the only area where it beats the uSDX radio, but both are pretty insignificant for my use.
Using it for SSB TX? Here's my comment: It works. Barely.... Enough said. Although, SSB reception really isn't bad. Since it is a general coverage receiver, I listen to many different stations and shortwave broadcasts. I don't bother using AM for SWL'ing, just keep it on USB and zero beat. AGAIN, use the ATT settings judiciously!
This radio is an experimential design type of radio and if you are into programing, there are facebook sites where you can find out how to update the firmware. I'm not into that and just live with what I have. I also do not recommend this for new ham operators or anyone that doesn't have experience operating QRP. It does take patience and a special touch, but it's very much worthwhile with this radio.
I will update as I gain more experience with the unit, but for now I really like using it for my picnic table portable CW adventures.
Operational shortcuts and info:
1. Press, hold and turn the tuning knob for Volume adjustment.
2. Double click the tuning knob to change bands.
3. Double click the Mode button to change bandwidth. |
|
| LNXAUTHOR |
Rating: |
2022-05-04 | |
| fun rig |
Time Owned: 0 to 3 months. |
there are a number of variants, and a 'newer' version of this single-board qrp rig... mine came with firmware R1.02w, says 'uSDR+' on the front, and puts out ~5W... sellers are mostly liars and cheats, and mine was no different, as the rig should have come with an internal battery (there is a charging port and circuit), but didn't, there was no documentation, no clue about pinouts of jacks, etc. a tiny Kenwood-style mic was included...
features of these rigs can vary: for example, the buttons-on-top versions usually have SWR/FWD/REF readout available via a menu item; some may have a voltage readout; and some sport a UART-labeled port that more often than not is non-functional...
digital modes should work on all variants using VOX, which can be adjusted via a threshold menu setting...
a PC CW keyer, using a 2N2222 circuit will work well with all variants using various logging programs or flrig's keyer dialog
fortunately, my uSDR+, which sports a CAT port, accepts a 'normal' TX/Tip FTDI USB cable for PTT digital operations... my first problem was that while wsjtx worked well for ptt using the radio designation 'TS480,' this did not work for flrig!
the solution: in flrig, select the radio designation 'TX-500,' which supports a subset of the 480's CAT commands, then use 38400, 8N1... voila! flrig works for various functions... you then can run fldigi and choose flrig as the controller... fldigi can then change mode, freqs, etc.
i won't get into the SSB functions of these rigs, which was always meant to be an experimental feature - voice transmissions can be adjusted using TX Drive audio gain, adjustable from 0-8... most rigs come with a default of 4, but perhaps dropping that to 3 or 2 may help with any distortion or muffling - you will have to test your rig to find out... the buttons-on-top model worked best for me using the built-in mic element about 5 inches away - these 'thin' variants do not have a built-in mic, so you are at the mercy of the included mic... one fellow remove the LED resistor in the tiny mic to help with more voltage to the element after replacing a specific board SMD resistor with half-value in an effort to improve audio - but test your rig, mic and menu settings first
these rigs are cheap, and you won't cry if you drop one over the side while kayaking, or off the tailgate of the truck onto concrete... if you pop the finals by transmitting too long into a bad match, the requisite trio of BS170 TO-92 replacements will cost you less than a small cup of burnt java from that evil coffee-shop chain
all in all, this is a fun little rig, but as mentioned on my other review of the buttons-on-top, using one is an exercise in the managment of low expectations - you may be surprised! |
|
