QCX: a feature-packed, high performance, single-band 5W CW transceiver kit, with WSPR beacon and built-in alignment/test equipment. Available for 80, 60, 40, 30, 20 or 17m bands. It has rotary encoder synthesised tuning, VFO A/B/Split, Iambic keyer, CW decoder, and more...
The "QCX" is a 5W, single-band, high performance CW transceiver kit with WSPR beacon, and built-in alignment/test equipment. It is available for 80, 60, 40, 30, 20 or 17m bands. See below for the long list of features! This is a kit of parts that you assemble yourself. There are NO surface mount components to solder (two SMD ICs are already factory pre-soldered). We do not currently have any enclosure available for this kit, it may be something we investigate in the future.
Assembly and operating instructions
The assembly document includes circuit diagram and a detailed description of transceiver operation. Please download the correct assembly instructions for your PCB revision. The PCB revision is the number in the bottom right corner. Kits shipped since 15-Jan-2018 use the Rev 3 PCB. The changes for Rev 3 are:
1) Includes the modification for reliable microcontroller startup: re-routing of tracks for existing inductor L5
2) Includes the modification for occasional PA instability on higher frequencies: additional 10K resistor R64 now supplied
3) Includes the modification for easier LCD contrast adjustment: additional 3.3K resistor R65 now supplied
4) Larger holes for 3.5mm socket (Key, Audio out) ground connections, to make fitting this component easier
- PCB Rev 3 Manual A4 format, CLICK HERE - for world except North America (document revision 1.10, 26-Jan-2018
- PCB Rev 3 Manual Letter format, CLICK HERE - for North America (document revision 1.10, 26-Jan-2018)
- PCB Rev 3 Manual GERMAN, CLICK HERE - A4-format German translation contributed by Peter DL6DSA (THANKS!) (revision 1.10a, 10-Feb-2017)
- PCB Rev 1/2 Manual A4 format, CLICK HERE - for world except North America (document revision 1.08, 23-Oct-2017
- PCB Rev 1/2 Manual Letter format, CLICK HERE - for North America (document revision 1.08, 23-Oct-2017)
- PCB Rev 1/2 Manual GERMAN, CLICK HERE - A4-format German translation contributed by Peter DL6DSA (THANKS!) (revision 1.08, 23-Oct-2017)
- PCB Rev 1/2 Manual JAPANESE 3-parts: part-1 part-2 part-3 translation of sections 1-4, contributed by Shig JA1XRQ (THANKS!) See Shig's website for single doc (revision 1.08, 06-Nov-2017)
- PCB Rev 3 Hi-resolution (300dpi) circuit diagram/schematic, 4,368 x 2,282 pixels
- Easy to build, single-board design, 10 x 8cm, all controls are board-mounted
- Professional quality double-sided, through-hole plated, silk-screen printed PCB
- Choice of single band, 80, 60, 40, 30, 20 or 17m
- Approximately 3-5W CW output (depending on supply voltage)
- 7-16V recommended supply voltage
- Class E power amplifier, transistors run cool… even with no heatsinks
- 7-element Low Pass Filter ensures regulatory compliance
- CW envelope shaping to remove key clicks
- High performance receiver with at least 50dB of unwanted sideband cancellation
- 200Hz CW filter with no ringing
- Si5351A Synthesized VFO with rotary encoder tuning
- 16 x 2 blue backlight LCD screen
- Iambic keyer or straight key option included in the firmware
- Simple Digital Signal Processing assisted CW decoder, displayed real-time on-screen
- On-screen S-meter
- Full or semi QSK operation using fast solid-state transmit/receive switching
- Frequency presets, VFO A/B Split operation, RIT, configurable CW Offset
- Configurable sidetone frequency and volume
- Connectors: Power, 3.5mm keyer jack, 3.5mm stereo earphone jack, BNC RF output
- Onboard microswitch can be used as a simple straight Morse key
- Built-in test signal generator and alignment tools to complete simple set-up adjustments
- Built-in test equipment: voltmeter, RF power meter, frequency counter, signal generator
- Beacon mode, supporting automatic CW or WSPR operation
- GPS interface for reference frequency calibration and time-keeping (for WSPR beacon)
There have been several firmware updates since the 21-Aug-2017 launch of this QCX CW transceiver kit. These provide enhancements and bug fixes. If you have an AVR programmer you can update your firmware using the on-board programming header. The firmware version history and more information are on this page (click!).
CLICK HERE for a Modifications page, various improvements you can easily make to your QCX radio.
These photographs show the prototype kit, both with and without the LCD module plugged in. The powered-up kit shows the radio's Frequency Counter feature measuring the frequency generated by its Signal Generator feature.
Builders' enclosure photographs
A common question about the QCX transceiver, is about what case to use for it. There is not an official QRP Labs enclosure for the QCX. But many people are finding their own solutions to this question.
For photos and information about what some constructors have done about enclosing their QCX, visit the QCX builders' gallery page!
IMPORTANT: SLOW SHIPPING: Note, order volume of this kit was (and is) extremely high. It will take some time to ship out all the orders and the shipment office already have high order volume. Please be patient. Your CW transceiver kit(s) will be assigned a Serial Number, notified to you by email. The chart below shows shipment status and we be updated several times per week.
QCX shipments are by default done in chronologically by order placement date. However the shipments may be re-arranged in some cases, such as:
- Prioritization or holding of an order due to some particular customer request
- Some parts may run out of stock unexpectedly, and so an order may be waiting for supplies to arrive
- An order may also contain other non-QCX items and for various reasons, there may be delays on those items
- Additional help to try to speed up shipments, means some QCX orders may be shipped in blocks from other locations
- Other logistics reason, in our attempt to get the backlog of QCX kits shipped as quickly as possible
In the chart below, you can find your order status, by looking at the row + column headers. The colour coding is according to the key (see right) and shows the band of shipped QCX orders. Where the colour is BLACK, it means that the order included several QCX kits for different bands, or included LPF kits for other items in the order. WHITE colour means the order is pending shipment. GREY means it that the serial number has not yet been allocated (or may mean a cancelled or re-ordered item). From this chart you can get an impression of how orders are progressing, and where your order is in the queue.
If your serial number is lower than the first row of this chart, it means your kit has been shipped already. Once your order has been shipped, you can visit the shipping statistics page to get an approximate idea of how long it will take to reach you.
LAST UPDATED: 16-Feb-2018
Serial numbers breakdown:
- 1 to 90, were the 90 kits for the YOTA 2017 summer cap (see below)
- 91 was assembled by QRP Labs as a final check of the assembly instructions
- 92 to 176 are for certain pre-orders, mostly taken at Friedrichshafen in July 2017
- 177 to 492 general sales of the first batch, starting 21-Aug-2017 at 09:00Z
- 493 to 987 are general sales, PRE-orders of the second batch
- 988 (approx) and up are general sales, PRE-orders of the third batch
- 1488 (approx) and up are general sales, PRE-orders of the 4th/5th batch
- 2488 (approx) and up are general sales, PRE-orders of the 6th/7th batch (expected to start shipping around end-December 2017)
Videos and reviews of QCX
The kit was originally designed for the RSGB Youths On The Air summer camp buildathon in August 2017. This RSGB YOTA Vlog video, shot at QRP Labs booth at Friedrichshafen 2017.
For more videos and reviews please see the QCX videos page!
The following issues have arisen more than once, and have the solutions indicated.
|Microprocessor does not boot up at power-up, requires switch-off/switch-on again to power up properly||See modification here|
|Power Amplifier instability results in low or unstable power output, or high current draw, or blown MPS2907||See modification here|
|LCD contrast fluctuates on transmit||Check for LCD module frame short to L2, see here for details|
|Low output power on 20m (or other band)||LPF inductance is probably too high, resulting in attenuation at the transmit frequency. Remove turns one at a time from LPF inductors L1, L2, L3|
|No power output at all||Check continuity through L1, L2, L3 and other inductors L4 and T1, as advised in the manual. Probably one or more have not properly burnt off the enamel so there is no electrical connection.|
Performance measurements by Wd WA4MZS
Ed made some interesting measurements of his 40m QCX serial number 354 (see also builders' photos page).
- Power supply = 13.8 VDC
- Current draw (receive) = 123 mA
- Current draw (transmit) = 514 mA
- Transmitter output (50Ω load) @ 7.020 MHz = 4.0 watts
- Receiver MDS @ 7.020 MHz = -121 dBm (0.2 µV)
- Reference frequency = 27.004345 MHz
- Transmitter frequency (display 7.020 MHz) = 7.0200003 MHz
- Transmitter 2nd harmonic (14.040 MHz) = -48.74 dBc
Spectrum analyser close-in and wide screenshots: