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Reviews For: (tr)uSDX

Category: QRP Radios (5 watts or less)

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Review Summary For : (tr)uSDX
Reviews: 13MSRP: ~$80 kit, ~$120 prebuilt
A menu-driven QRP open-source transceiver designed by DL2MAN and PE1NNZ. At the current time, it covers 80, 60, 40, 30, 20 meter bands.
Product is in production
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
E78CB Rating: 2023-09-16
Gives more than it costs Time Owned: 6 to 12 months.
Nice SDR rig from DL2MAN/PE1NNZ. The project was planned to be a basic digital but still useful rig, getting roots from QCX unit from QrpLabs , but it turned out to became more than decent and very popular unit for QRP work. It has many nice features. This version covers 80-20m bands, but I figured out it can also work on 17m and even 15m but with diminished characteristics on RX and TX. Being so small and with internal keyer it is now my main rig for hiking and portable operation. Sure, there are more capable and more quality ones with similar size factor out there, but concerning it's price, it is a very nice and capable "grab an go" unit.
W6SSP Rating: 2023-06-13
Very capable CW transceiver Time Owned: 0 to 3 months.
I've been fascinated with HF receivers, their design and
tradeoffs for over 50 years and have a decent collection
of high performance tube and solid state receivers over
the years including R-390 series, Collns 51J and 75A,
SP-600, Racal RA-17, SX-28, ICOM R-9000 and others. So until
recently never had much interest in acquiring an SDR
receiver, or in this case transceiver despite using DSP
techniques as an engineer a few times and being curious
about SDR performance.

A friend gave me a dead (tr) uSDX a while ago and
was able to fix it (broken trace). And while comparing
it to any of the receivers mentioned above is not fair,
I was rather impressed with it. While it was not very
sensitive and had many internally generated spurs
(aka birdies), especially on 20m, other features made
up for these short comings.

Notably the DSP filters in CW mode. Other very useful
features include; 5 bands, CW/LSB/USB/AM/FM modes,
internal IAMBIC keyer/straight key option, SWR/power
meter, two types of S-meter, RIT, useful CW reader
and built in AGC. All in a package the size of a deck
of cards! Nifty.

This seems to be designed primarily as a CW rig and
it works quite well in that mode. I'm getting 3.8 watts
out into a dipole on 20m with a low SWR with 12.4vdc
supply which is apparently typical. It does not do
well into an open or short as I found out the hard way
but the FETs are easy to replace.

In SSB mode the receiver works quite well but transit is
another story. Rather distorted even with an external

Some have mentioned a high noise floor in the receiver.
I haven't noticed that but perhaps because I'm using
threaded metal spacers between the PC boards,
providing a much better ground.

Things that could have been done better; seemingly
random (at times) button entries. This can get rather
annoying when trying to navigate the menus which
I have found to be logical once you get accustomed to the layout.

The display is tiny but bright and well laid out with
all pertinent info right there. And can be configured
many ways.

To summarize, this beastie has me hooked on tiny
SDR/DSP transceivers and are a bargain in the $100
class. Very capable and with some patience many
contacts can be made. Although it looks like it in the
gaudy orange case (IMO), this is no toy.
W4PUO Rating: 2023-05-07
easy assembly with youtube video. Still in work Time Owned: 0 to 3 months.
I bought after reading May QRP Quarterly article and assembled in one day. Winding 13 torroids took most of my time. I still need to add firmware to get it on the air. Power up with UMB went fine. I need to locate a power plug to fit 3.5mm 1.3 barrel.
Now two days later and all is complete including the beta firmware just offered by Manuel. Heard ssb and cw stations using my 14.2 dipole but need to learn more about menus before I get it on the air -- practice cw too.
Most fun I've had for $100 since the Air Force. Thanks to the gurus at DL2MAN and PE1NNZ
W4RKU Rating: 2023-04-18
Cool little radio Time Owned: 0 to 3 months.
It is an amazing radio for the price and size. Very pleased. Use with both CW and Dig and no real complaints. Audio isn't rich but not surprising. What is surprising is how well it works!
K9EX Rating: 2023-02-28
Excellent QRP Value for POTA or Home Use Time Owned: 3 to 6 months.
The (tr)uSDX QRP delivers in spades - especially for POTA activations. Yes, the receiver and speaker tend to overload a bit but you can typically lower the volume and you'll be fine (see Tip below).

The selectable rx bandwidths are a nice touch - you can use the wide open 4K bandwidth as sort of a "poor man's bandscope" in the sense that it will let you hear more signals when negotiating a POTA pileup. (Try that with a QCX+/Mini or other fixed-bandwidth QRP rig.)

Throw in 5 bands, ATT and NR, the very small form factor, a fairly usable built in speaker, SWR and PO meter settings (use PTT button with Straight key setting to check SWR/PO), plus SSB with built-in mic and this little marvel is delivering way beyond its price point.

FYI, my unit draws about 0.15 A on rx and just under 0.5 A on tx so even a small 3000 mA battery will power this rig and its +5W output well past the point where you're either too hot, your hands are frozen or you're just tired of that hard park bench!

Tip: To help prevent receiver overload, I have been turning the AGC off (menu 1.8) and increasing the default ATT2 setting (menu 1.11) from 2 to 4. This quiets the receiver and will let you increase the volume - then it's easier to throttle overloading signals with the volume control. I also typically set the rx bandwidth to 1.8 KHz as that setting seems to provide the least noise to my ears while still allowing for off frequency callers during POTA deployments.
NB4M Rating: 2023-02-13
$100 of pure fun Time Owned: 0 to 3 months.
Is it quirky as mentioned in pervious reviews? That's not been in my experience (CW ONLY). It performs all five bands as advertised and does a good job at it. Although it's probably best when using earphones, the experienced operator will easily find the performance limits of this little jewel (as with any) and enjoy a quality QRP experience.

Is it worth the cost? That and more! It's as good or better than any other QRP rig out there. Have two of these now and pleased with both.

Is it small, cheap and QRP fun? Yes.
W7ASA Rating: 2022-12-09
Pleasantly Surprised Time Owned: 3 to 6 months.
I saw this reviewed on my friends' YouTube channel and decided to buy one from the 'approved' vendor from the PRC. It arrived quickly and worked immediately, though I did calibrate the dial so that it would zerobeat on WWV.

I'm primarily a CW hound, but the ssb voice capability using the built-in front panel mike has been tested, when I was able to check-in to the Maritime Mobile Service Network, with good audio reports. For me though, CW is where this rig really shines. Filters are adjustable from 4 KHz down to 50 Hz bandwidth and that is useful for me. Being a general coverage receiver allows me to listen to shortwave broadcasts using a sideband in zerobeat with the station. Audio fidelity is communications grade, definately not HiFi; if this is a problem, moce-on beause this is not the radio for you. For a toss-in-the-bag and go to the beach rig, this is excellent at this pricepoint. It has 80 meters, which for me is a must. Night time regional comms are important to me.

A few cons:
1. The audio is somewhat unstable, in that if you increase volume above 11 or so, the rig produces a howling noise. If AF gain is kept below this threshold, no problem.
2. Like most modern small rigs, the menus are usually less than intuitive and this is no exception, the difference is that this rig is a fraction of the competing QRP and /p rigs in its price range. Once learned, the menu is not difficult at all to use.

So - small batteries (I use an 8x AA battery pack [ Eneloops]) will power this for a long time . See the specs and do the math - it's impressive.

If you're thinking of buying one, I encourage you to do it.

73 / 72 de Ray ..._ ._
LNXAUTHOR Rating: 2022-12-08
affordable qrp fun Time Owned: 6 to 12 months.
this is the real deal, a tiny 5-bander supporting usb, lsb, and cw... (forget about transmit using am or fm, not gonna be useful)

i was pleased to discover that more than adequate reception of a favorite local AM BCB was possible using lower sideband (LSB)

you must use headphones even though there is a little speaker; expect howling with too high levels... balance NR, filtering, and attenuation to achieve decent audio

these units are shipped pre-assembled supporting the 80-60-40-30-20m bands... you cannot change the band range via the menu, although the firmware allows you to do so; there are two other boards in kit form for non-WARC (10-15-20-40-80) and high bands (20-17-15-12-10); you will need to buy them, assemble, then use on your rig or another kit rig

each rig rig comes with a serial number (in the boot loader); you can then go to dl2man's web site and download a 'custom' firmware to reflash the transceiver... the only custom thing about the firmware will be that you can have the rig display your callsign... the rig, out of the box, displays no callsign... next, run averdudess under winblows10... here's where you may get frustrated: you *must* use a data-capable micro usb cable, or your pc won't assign a COM port... i had to search through the junkbox after trying three different cables (an old usb hard drive cable worked)... plugged in the cable, loaded my new firmware, and reflashed the rig... worked FB

an important task after reflashing is to zero beat the 'ref freq' menu setting to make sure the rig transmits and receives on the displayed frequency; you can change the ref freq setting up or down to get on frequency; i used my 705 to record transmissions to fine-tune the frequency and voice modulation in sideband - the result is an important difference between the tr(usdx) and the usdx+ clones: the tr(usdx) has acceptable voice modulation in usb/lsb! but both rigs are great for CW and as CW training transceivers

the firmware is currently rev 2.00i, although dl2man offers a beta as well.. quite frankly, as an owner of a usdx+, the tr(usdx) firmware offers fewer features (but does have one custom keyer message and CAT, which i did not test)... the open-source usdx+ firmwares on the FB group have many more options (such as IQ streaming, multiple CW messages), while dl2man, who got chafed at offshore cloners, has closed his source (dumb idea in my opinion), and you can only download precompiled arduino .hex files

while the usdx+ offers a wider choice of open-source firmwares and 8 bands vs the 5 bands of the tr(usdx), along with the option for internal 3s 18650 cell battery, the tr(usdx) does have some unique features: light weight, tiny form factor, ptt/straight key button (along w/a 'tune mode'), usb reflashing (although you can do an ISP port reflash), operation at QRPp (milliwatt) levels via usb power...

an sma is used instead of BNC, but an adapter and power pigtail is included with assembled units (don't know about the kits)

the 3D printed case is nice and sturdy, and there are even laser-cut clear cases available

the tr(usdx) OLED is unreadable in sunlight, unlike the usdx+, which offers backlighting on/off... there is a mod to increase the brightness but you will lose the ability to operate the rig via usb due to voltage use by the mod

i drilled two small holes in the back plate and bolted on a 3S 18650 battery holder; there is no on/off switch so i just plug in the 3.5mm x 1.3 barrel to power up

the tr(usdx) also has SWR and voltage readouts - in straight key and CW mode, press the ptt button and you will see swr and voltage, depending on your menu's meter selection... i found my rig to be pretty much spot on

there are probably a vast number of hardware differences between the clones and the tr(usdx), but the fact is that documentation is poor for both rigs... for example, try finding a description or example of using the built-in line editor to edit the CW message (you can add characters, but in order to erase a character you must scroll through the selection and enter a blank character - a symbol should have been used), or written tips on various button presses or a general reset (hold down menu while powering on); no manual is included, so you will have to read dl2man's docs, and watch his videos to learn more

i am happy with the rig, but understand this about it and other variants: due to the memory size of the atmega328p, there is no room for expansion.. these rigs are experimental... they are great CW rigs with decoding and messaging, and can be used for voice...

but they are dead-end in the development cycle... PE1NNZ has done an amazing job on squeezing in features and wringing performance out of the atmega328p, but this rig and the clones are, repeat, dead-end in the development cycle... get yours if you wish, but they will never approach the features and performance of commercial qrp rigs... however, it is great to have a little rig in the pocket for fun, and you will make contacts
K6ELV Rating: 2022-12-08
Lots of radio for the price. Time Owned: 6 to 12 months.
First off, let me start off with the good:
This radio packs many features in an extremely small package. At about the same size of a VHF/UHF handheld you get a radio that can work on 5 HF bands plus general coverage receive in all modes with an onboard microphone and speaker at full QRP power of 5 watts all for less than $150! You will not find any other HF transceiver like this anywhere near this price point. Heck, there are even many shortwave radios which are receive only that are close to the price of this transceiver. With the extremely small size and low power requirements (has the ability to be powered solely from USB) you can take this virtually anywhere which makes it perfect for POTA, SOTA, field day, or go bag. Paired with a battery case or USB power bank and a telescopic HF antenna such as an HFJ-350m you can theoretically have a fully functioning HF station in the palm of your hand.

Now for the negative:
With the small size and small price this radio does have some compromises.
1. The radio has a somewhat high noise floor that seems to be internally generated. Because if this it will not pick up weaker signals as they are drowned out by the noise. I hooked up the same antenna to a different radio and the signals were easier to copy with less noise.
2. The small speaker is not very loud, while it can be easily heard in a perfectly quiet environment, it can be nearly impossible to listen in an environment with any sort of noise unless you place the speaker right up to your ear. Another problem is if you turn the volume setting beyond a certain level the audio circuit self-oscillates and causes a horrendous squeal in the audio.
3. The firmware seems glitchy, there were times I was tuning around the band and the radio completely froze up and I had to remove the power to reset it.

All in all I would say this radio definitely met my expectations considering the size and price. Having a radio this size with this many capabilities was basically unheard of. In the past, other HF transceivers of this size were typically single-band CW only and a few ten to a few hundred milliwatts, but this thing gives you 5-band SSB voice capability with 5 watts of power.
KL7KN Rating: 2022-11-07
Best deal going for a new rig! Time Owned: 6 to 12 months.
One of the best **bang for the buck** radio now found on the market.
It does have a bit of a learning curve, so reading the manuals found online is a must. SSB works to provide a snappy, readable signal and the CW works well. There is a bit of a pop at the end of each character. Speed set and forget.
Multiple filter options. Multi-mode - AM/FM/CW/SSB. Will NOT work on CB before you ask.
Broadband RX.
Non-vendor accessories now showing up on the market like a matching battery case.
Very happy with mine, well worth the $149 for the assembled unit.