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1.

Introduction

The QMX is a high performance, five-band 5W CW and Digital modes transceiver with CAT 
control and built-in USB sound card. 

80, 60, 40, 30 and 20m operation, with 5W from a 9V or 12V supply (build options)

Clean single signal output (zero residual carrier, zero unwanted sideband)

Sunlight viewable, large 16 x 2 character yellow/green LCD, switchable backlight

Built-in SWR metering and protection

Lightweight: 

210 grams

Solid state PIN-diode switched Low Pass Filters and solid state Band Pass Filters

Solid state transmit/receive switching

High performance embedded-SDR SSB receiver using 112dB 24-bit stereo ADC chip

Built-in USB sound card: 48ksps 24-bit stereo 

Built in USB Virtual COM port serial for CAT control

Si5351A Synthesized local oscillator with better than 0.001Hz resolution and high precision 
25MHz TCXO reference as standard 

Built-in signal generator

Built-in suite of configuration and analysis tools

Built-in iambic keyer

On-screen S-meter

CW decoder

CW: Full or semi QSK, fast break-in; VFO A/B/Split, RIT, configurable offset, sidetone

Beacon mode: standalone CW, FSKCW or WSPR operation

GPS interface for real-time clock and frequency discipline for WSPR operation

Lifetime free firmware upgrades with QRP Labs Firmware Update (QFU) bootloader for 
easy firmware update on any OS with no extra software, or drivers, or programming 
hardware

All SMD components pre-installed by factory, only through-hole component soldering by the
kit constructor

Low receive current (switching buck converters) 80mA; Transmit current 1.0 – 1.1A 
(transmit dependent on power supply; example is approximately for 9V supply, 5W output)

Connectors: USB-C (audio and serial for CAT), Power, PTT (external amp), audio out, 
paddle and RF

Optional smart aluminium extruded enclosure measuring just 95 x 63 x 25mm

No test equipment is required to build, align and operate this digi modes transceiver. All 
adjustments can be made using built-in test equipment; or left alone (the transceiver will work well 
even with no adjustment). 

We hope you enjoy building and operating this kit! Please read this manual carefully, and follow 
the instructions step by step in the recommended order. The construction is necessarily very 
compact and so it is important to really give attention to ALL the details described in this manual. 

The circuit theory is described in detail in another document and we recommend reading and 
understanding this section too, to get the maximum enjoyment and education from your new radio.

The operating manual is a separate document and will get you started with QMX with CW, 
or with your WSJT-X or other digi modes software, in minutes. 

PLEASE READ THE BASIC ASSEMBLY AND USE INSTRUCTIONS IN
THIS MANUAL VERY CAREFULLY BEFORE APPLYING POWER TO 
THE BOARD!

QMX assembly Rev 1.00e

3

Summary of Contents for QMX

Page 1: ...QMX QMX QRP Labs Multimode Xcvr transceiver Assembly manual PCB Rev 1 QMX assembly Rev 1 00e 1...

Page 2: ...ader connector sockets female 42 2 17 Install power supply boards 43 2 18 Install LCD module 47 2 19 Install 2x5 pin and 2x2 pin male pin header connectors 48 2 20 Install four 11mm nylon spacers 48 2...

Page 3: ...update on any OS with no extra software or drivers or programming hardware All SMD components pre installed by factory only through hole component soldering by the kit constructor Low receive current...

Page 4: ...half way at 1 5 turns The secondary no tap will now be only two turns The chart below shows the measured power output vs supply voltage for the standard 3 3 winding Red line at 12 V supply the output...

Page 5: ...correctly installed the first time In the event of a mistake it is always best to detect and correct any errors as early as possible immediately after soldering the incorrect component Again a reminde...

Page 6: ...o discontinuity of the ground return paths Frequent ground plane stitching also prevents the creation of internal microwave cavities which could resonate and enhance noise propagation between harmonic...

Page 7: ...f the PCB panel with the constituent parts outlined in red The easiest way to break out the boards is to use needle nosed pliers or wire cutters grab each of the breakaway tabs colored in yellow and g...

Page 8: ...QMX assembly Rev 1 00e 8...

Page 9: ...rection to the nearby SMD component 8 KEEP the component lead offcuts from the capacitors they are used later when installing the LCD module 9 Solder connectors with no more heat and time necessary to...

Page 10: ...QMX assembly Rev 1 00e 10...

Page 11: ...QMX assembly Rev 1 00e 11...

Page 12: ...QMX assembly Rev 1 00e 12...

Page 13: ...Trace layout Top side components Bottom side components LCD and controls board are on the following page there are no SMD components on the bottom side of these boards QMX assembly Rev 1 00e 13...

Page 14: ...QMX assembly Rev 1 00e 14...

Page 15: ...QMX assembly Rev 1 00e 15...

Page 16: ...QMX assembly Rev 1 00e 16...

Page 17: ...R108 R109 R208 R209 R212 R502 R503 R518 R521 R523 19 1kK SMD 0603 R102 R106 R107 R204 R213 R214 R215 R216 R401 R402 R405 R406 R501 R505 R508 R510 R519 R524 R526 7 22k SMD 0603 R110 R111 R112 R113 R20...

Page 18: ...3 10u SMD 0805 C420 C421 C502 4 4 7n SMD 0603 C422 C423 C424 C425 2 10n SMD 0603 C426 C427 4 10u Tantalum case A style C431 C433 C435 C439 2 1u Tantalum case A style C432 C437 1 470u Electrolytic 10V...

Page 19: ...01 L102 L501 4 47uH axial inductor L505 L507 L509 L514 2 FT37 43 L502 T401 1 BN43 202 binocular 3 3 T501 1 BN43 1502 binocular T507 Miscellaneous Qty Value Description 1 2 1 mm DC 2 1 x 5 5 barrel DC...

Page 20: ...ng M3 screw 1 M3 Steel M3 nut 1 M3 12 mm Steel 12mm diameter M3 washer 5 M3 x 11mm Nylon threaded hex spacer 12 M3 x 6mm Nylon screw 2 M3 x 9mm Nylon screw 6 M3 Nylon nut Enclosure OPTIONAL Qty Value...

Page 21: ...221 C402 1 270pF Label 271 C516 2 390pF Label 391 C515 C524 2 470pF Label 471 C523 C519 2 820pF Label 821 C518 C514 1 1200pF Label 122 C517 Inductors powdered iron Micrometals toroids Qty Description...

Page 22: ...2 4 Inventory parts Note Photo shows parts for 80 60 40 30 20m version of the QMX Note Capacitor colours vary depending on availability All are NP0 C0G Class I RF dielectric QMX assembly Rev 1 00e 22...

Page 23: ...ome capacitors may need to be bent to fit the 2 5mm spaced holes Be careful not to damage nearby SMD components when soldering or clipping the capacitor leads Also note that ground pin connections req...

Page 24: ...hode end The white stripe end must be aligned with the white stripe on the image on the PCB silkscreen The end with the white stripe is shown with a blue dot in the diagram below For D508 D511 the whi...

Page 25: ...or body stands up vertically at 90 degrees to the PCB The orientation of these is not particularly important but my recommendation is to follow the silkscreen PCB pattern putting the body longer lead...

Page 26: ...70 transistors in the positions shown with their flat faces flush against the PCB Use the 12mm M3 bolt washer and nut to firmly press the transistor faces against the PCB as shown Refer to the diagram...

Page 27: ...e turn primary winding has a center tap In the nomenclature of binocular cored transformers 1 turn means the wire passes through both sets of holes ending up back at the end where it started Assembly...

Page 28: ...usion Step 6 Squeeze together the center tap to try to avoid subsequent confusion Step 7 Start the 3 turn secondary winding by pushing the wire from right to left through the bottom hole of the binocu...

Page 29: ...ring iron to the wire until the enamel burns off But that doesn t work so well on thicker wire such as this So my technique here is to scrape the enamel off at least partially using wire cutters The c...

Page 30: ...lenty of solder and hold the soldering iron tip to the joint for maybe 15 seconds to really be sure of a good joint and burning away any remaining enamel Step 16 Check that none of the wires protrude...

Page 31: ...beled B and check for continuity Finally there should be NO connection between A and B Hold one probe on any A point and the other probe on a B point That should read infinite resistance no continuity...

Page 32: ...ion of the taps at 19 30 and 38 turns which have larger holes such that two wires can be inserted Carefully unwind and cut off approximately 80cm of the 0 33mm AWG 28 enameled wire and straighten it e...

Page 33: ...asy to fit through the large holes at the 19 30 and 38 turn taps see photo right Step 7 Insert all the wires in their correct holes You should pull them firmly from the underside of the board to ensur...

Page 34: ...k for continuity between pins 3 4 5 6 and 9 of IC3 as shown You should measure 0 ohms continuity between any pairs of these If you do not then there is a mistake somewhere most probably a failure to b...

Page 35: ...l the toroidal inductors in the QMX kit you will get it right if you start as shown photo above right and pass the wire through the toroid from the top side down through the hole out and then around a...

Page 36: ...of the toroid counts as one turn Spread the turns evenly with a small gap Winding the toroids as tightly as possible will slightly improve the performance of the Low Pass Filters But don t pull so ti...

Page 37: ...ould use a vise if you have one If you don t then you have to get creative and think of something Here I taped it to the edge of the desk Now you can twist the screwdriver at the free end repeatedly u...

Page 38: ...ntil the enamel burns off Now use a DMM to test for continuity Re arrange the wires so that there is continuity from A A B B and C C in this photo Carefully keep this orientation of wires and insert t...

Page 39: ...older on the joint for at least 10 seconds to make sure the enamel burns off completely The photograph right shows the trifilar wire ending holes labeled A B C on the lower side of the PCB You should...

Page 40: ...f the ends before installation but not tinned it would not fit in the holes The thinner 0 33mm ends of the 10 turn windings are fitted at A A and D D The transformer is designed to sit in the cut out...

Page 41: ...rtant to apply necessary force to hold them in the correct 90 degree orientation with respect to the board edge during soldering When the connectors are well aligned you will have no trouble fitting t...

Page 42: ...r connectors 2x5 pin header connector socket female 2x4 pin header connector socket female 2x2 pin header connector socket female Be careful to ensure that the pin headers are accurately aligned they...

Page 43: ...w with its head end on the underside of the main PCB M3 nylon nut fitted on the top side of the main PCB as a spacer These need to function as a spacer turning freely not as a nut You need to drill ou...

Page 44: ...board Take care not to damage the nearby 2x5 pin connector or BS170 transistors or any of the delicate SMD components on the power supply boards The diode shown is particularly vulnerable 4 2x4 pin an...

Page 45: ...k square Only then are you are ready to solder the 90 degree male headers 2x4 pin and 2x3 pin to the main board Again do not try to force them to sit flush on the surface of the main QMX PCB Have them...

Page 46: ...nector body 9 CHECK It is very important to check all the connector joints both the edge connected female header connectors on the power supply boards AND the male 90 degree headers on the main board...

Page 47: ...rough the rectangular cut out Bolt the LCD module ensuring equal gaps at top and bottom tighten screws firmly Drop component off cuts through the 16 holes their bottom ends sitting on the bench Solder...

Page 48: ...header sits squarely and centrally in its allocated position Install and solder the 2x2 pin male header similarly on the right hand side of the board 2 20 Install four 11mm nylon spacers Install four...

Page 49: ...ure later Therefore it is necessary to cut off the protruding feet using a wire cutter so that the potentiometer can sit flat on the PCB Follow the steps below to install this part Cut each little pla...

Page 50: ...main QMX PCB in reality but is shown separately here for clarity Use a screwdriver to firmly push down on the plastic former of the 2x4 pin header as shown to slide it down the long pins until it sit...

Page 51: ...ve switch pins Bend over the pin through 180 degrees so that it points to the front of the control Repeat the same procedure for the four remaining pins Install the rotary encoder first line up pins s...

Page 52: ...tton is seated squarely on the PCB so that the shaft is perpendicular to the PCB Solder two diagonally opposite pins first then check the alignment and make any adjustments necessary when all is well...

Page 53: ...CB using an M3 6mm nylon screw Push the screw through the hole from the front side of the PCB Thread the small square spacer PCB that was broken out from the Display PCB panel onto the screw Then scre...

Page 54: ...e of the main PCB screwed into the 11mm nylon hex spacer pillar that is fixed to the Controls PCB as shown in the following photograph 2 28 Plug together the boards There is a mechanical conflict betw...

Page 55: ...d the 2 pin header at the top right to mate accurately with each other The rest should fall into place by itself If you have taken care particularly with filing off the rough edges of the PCBs when th...

Page 56: ...he Display board and the main board with the controls board bolted in position Peel off the plastic protective coating from the LCD module Here s the top half of the enclosure Note the PCB guide rails...

Page 57: ...This is how it looks from the DC connector end Determine correct orientation of the bottom half of the enclosure note the tongue and groove arrangement which means that the bottom half only fits one...

Page 58: ...lied knobs by tightening their grub screws Leave a small gap between each knob and the front panel to allow the knob to turn easily The grub screw of the volume control knob should be at the position...

Page 59: ...configured it The GPS produces two output signals PPS Pulse per second and RxD Serial data A GPS such as the QRP Labs QLG2 is perfect for this see http qrp labs com qlg2 QMX cannot supply 5V for the...

Page 60: ...signal on the ring and makes no connection to tip During transmit the microcontroller activates ONE of the PTT signals you may configure which one according to your needs It should be noted that The...

Page 61: ...in and 2x3 pin right angled headers which connect to the plug in buck converter boards Look for dry joints and any solder bridges or other faults Check the edge connected female pin header sockets on...

Page 62: ...ave a 32 ohm impedance The output op amp IC IC10 is not able to supply the required power output for loudspeakers If you want to use a small loudspeaker you will need to ensure this is an amplified sp...

Page 63: ...RP Labs website and are encrypted using 256 bit AES encryption technology Entering bootloader firmware update mode Note you have to switch on QMX by pressing the left rotary encoder shaft button In fi...

Page 64: ...ware file in this example is named shows a single file which is the firmware version file 1_00_001 QDX in this example The EEPROM file is always named EEPROM QDX You can read and write EEPROM files in...

Page 65: ...only work on a QRP Labs QMX board it cannot be installed on any other board even one containing the same processor No other firmware file will work on the QRP Labs QMX board except an official QRP La...

Page 66: ...sources For updates and tips relating to this kit please visit the QRP Labs QMX kit page http qrp labs com qmx For any questions regarding the assembly and operation of this kit please join the QRP La...

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