[PPRAANet] Fwd: [qrptech] New kit: QDX - Digital Transceiver by QRP Labs

Sat Oct 9 11:57:48 EDT 2021

For those that enjoy QRP.  Chuck N7CHS

-------- Forwarded Message --------
Subject: 	[qrptech] New kit: QDX - Digital Transceiver by QRP Labs
Date: 	Sat, 9 Oct 2021 17:52:26 +0300
From: 	Hans Summers <hans.summers at gmail.com>
Reply-To: 	qrptech at groups.io
To: 	CalQRP at groups.io, fpqrp at groups.io, gqrp at groups.io, NOGA 
<noGaQRp at groups.io>, qrparci at groups.io, qrptech at groups.io, 
radiobuilders at groups.io, QRP-L Mailing List <qrp-l at mailman.qth.net>, 
BITX20 at groups.io

Hi all

I am pleased to announce at last the availability of the new QDX 
transceiver. I actually developed this nearly two years ago but a lot of 
things got in the way of finishing the final touches to the firmware and 
documentation... ya know, Covid19, a new baby in the house, and of 
course QCX-mini and all it's associated teething troubles, along with 
keeping QRP Labs going...

QDX will cost $60 and the optional enclosure will cost $20.
The shop page is http://shop.qrp-labs.com/qdx
*Ordering will open at 1800Z on Monday 11-Oct-2021.*
The main QRP Labs page is http://qrp-labs.com/qdx
QDX Video: https://youtu.be/j6Vnh8eiEpg
Between now and Monday, you can read the manual and ask any questions. 
Please understand and read the manual before ordering.

So QDX... a four band 5W digi modes transceiver 80, 40, 30 and 20m. It 
produces 5W from a supply voltage of 9V using a new Class-D Push-Pull 
amplifier I developed specially for it. Most importantly, this is NOT an 
SSB transmitter! It suits any single FSK mode (such as FT8, JS8Call, 
WSPR, JT4, JT9, JT65 and more). It performs an analysis of the audio 
output by the PC program (e.g. WSJT-X) to determine the audio frequency 
then commands the Si5351A Synth to produce that frequency. As such, 
there is NO unwanted sideband transmission, NO residual carrier 
transmission, and NO IMD products due to amplifier non-linearities. Just 
efficient, clean transmission.

The QDX receiver is a high performance SSB received using an embedded 
SDR, with a high performance 110dB dynamic range, 24-bit, 48ksps stereo 
ADC chip and 32-bit ARM Cortex M4 processor.

All band switching and transmit/receive switching is solid state. No 
plug-in modules here, no relays. Everything is electronically switched 
by CAT control automatically when you change the band drop down in WSJT-X.

QDX also includes a 24-bit 48ksps stereo USB sound card for audio, and a 
USB Virtual COM serial port for CAT. Transfer of audio from WSJT-X to 
QDX is noise-free, lossless, just a pure transfer of digital sample 
information. Transfer of audio from QDX to the PC via the USB sound card 
is high fidelity without possibility of ground loops. No audio cables, 
no headaches - just a single USB cable between PC and QDX carries both 
audio and CAT commands. QDX has only three connectors: DC power, USB and 
RF (to the antenna).

The VFO is a Si5351A Synthesizer under CAT command from the PC. So it 
covers any digital frequency, not just limited to FT8 for example. QDX 
includes a 25MHz TCXO module as standard, as the reference for the 
Si5351A Synthesizer.

QDX includes its own internal signal generator and test tools suite too. 
You can connect a terminal emulator to it and explore the performance 
and techniques that make it work, as well as enter any specific 
configurations you may need. However the terminal application mode is 
not necessary for ordinary operation and most users will not need it.

QDX includes the QFU (QRP Labs Firmware Update) bootloader so lifetime 
free firmware updates are easy to install, just by loading the new 
firmware file into QDX using File Manager on your PC: works on any OS, 
no drivers, no software, no hardware e.g. programmer.

Due to an unfortunate self-resonance QDX assembly requires removal of 
four 47uH SMD inductors that are to be replaced with four axial leaded 
inductors (supplied). Furthermore, since QDX uses the AMS1117 voltage 
regulator, an additional electrolytic capacitor is supplied that must be 
soldered to connections on the top side of the board. Other risks of 
using the AMS1117 are mitigated by the fact that QDX has no ports where 
hot-plugging or shorts could cause any danger of AMS1117 failure - so 
this is not a risky situation as the first batch QCX-minis had.

The optional QDX enclosure is the same aluminium extrusion as used in 
the QCX-mini but of course is cut, drilled and laser-etched differently.

Initially, I produced a batch of 500 QDX, which I actually manufactured 
back in January 2020 before the Covid19 pandemic got started. On Monday 
11-Oct-2021 at 1800Z I will put a quantity of 450 QDX in the shop, for 
ordering. What of the remaining 50... well quite a few didn't make it 
through the firmware development and testing (when developing the QFU 
bootloader, I bricked quite a few QDX!)... and I am going to hold a few 
back in case of issues etc. losses in shipment, etc etc.

Due to the global semiconductor crisis, several of the ICs used are 
currently unavailable so I do not know when the next batch of QDX can be 
made available. I will begin researching sources or alternative ICs.

So - any comments and questions are welcome, the manual is there, 
available to read and understand so you can decide whether you would 
like to order one.

73 Hans G0UPL
http://qrp-labs.com

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