(tr)uSDX a very tiny radio that works....sorta.

[TACAIR]

The uSDX radio sets, a variant of the QRP Labs QCX radio have been on the market for some time now.

Sold on Amazon ( Amazon.com: tr usdx transceiver 5-Band usdx Multimode QRP Assembled with case by PE1NNZ and DL2MAN : Electronics) for $138.

5 watts, cw and ssb, tiny footprint.

Now, the bad parts.
Given the blatant theft of IP by many Chinese vendors (all the other uSDX radio sold) - all software updates provided by/for the (tr)uSDX radios are encrypted so can only be used by the original purchaser.  This via a long code provided with the radio.  See  DL2MAN.de – home of the (tr)uSDX  for the full scoop.

The display is tiny, wear your glasses.

The biggest fault - IMO - is that the radio is very sensitive to overvoltage.  Like many other QRP radios that use the BS-170 as a power amplifier (PA) device, it is easy to blow these out.  
SWR over or even near 2.0:1 will blow up the PAs as well.  Run the radio near the max voltage and with any SWR showing and you are replacing the FETs again.

The BS-170s are cheap - I bought mine Amazon- $8 for 100, shipping included.

Bottom line, I bought a QMX as a replacement.  I'll get around to replacing the BS-170s in mine - at some point.   

This is a neat toy, and a fun thing to play with.   AS a serious field radio - it falls too short in too many areas to consider.

If you are thinking of using (tr)uSDX as a SW RX - don't The TECSUN PL-368 is as good and a lot less expensive.

TACAIR.

[TACAIR]

(tr)uSDX on top, QRP Labs QMX on bottom.

for scale the QMX case is the same size as an Altoids tin, - with the knobs and antenna port going outside of the template.

uSDX rig, about $140 w/free Amazon shipping
The QMX just under $200. w/no free shipping from Turkey.

Both have excellent documentation.

The instruction manual for the QMX is over 100 pages and the rig has something of a learning curve.

Based on my use of both - the QMX is the vastly superior rig, even though you will likely have to wait 6 to 7 months for delivery after paying for it.  I was happy to wait, and my patience was rewarded, the radio is that much better.
***
The difference in the RX is night and day - the (tr0 uSDX is quite noisy, the QMX is dead silent until the CW note pops up.  The QMX is currently working on resolving an issue with birdies - these are numerous and on every band.

The QMX rig now is CW and single tone digi.  the usdx, is Am/FM/CW/SSB and digi - but I've only heard CW/SSB and a bit of digi.

Both 5 watts @12 volts - but as noted above, run either these rigs at 12VDC, and you run the real risk of blowing put the BS170s.

Both of these radios are derivatives of the original QCX - single band CW transceivers from QRP Labs.

[Z.O.R.G.]

Putting a voltage regulator (like a LM7812) in line with the input power source might Give the FETs an extra layer of protection from overvoltage.  I'd need to check the datasheet, but it should also provide reverse voltage protection.

[TACAIR]

QRPLabs@groups.io | Messages

has gems like th9is

QRPLabs@groups.io | I let the smoke out...

QRPLabs@groups.io | Q: Replacement for BS170?
various ways foe for your QMX to self-destruct.

I'm using a hard limit 11.3 VDC source.  SWR protection is set to 2.


The SW3B uses a IRF-510- FET and is bomb-proof....

Won't work in the QMX due to the modulation scheme used (class E waveform shaping)