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QRP Labs QMX Operating Manual

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QMX
QMX: QRP Labs Multimode Xcvr (transceiver)
Operating manual, firmware 1.02_000, 01-May-2025
1
QMX operating manual; firmware 1_02_000

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Summary of Contents for QRP Labs QMX

  • Page 1 QMX: QRP Labs Multimode Xcvr (transceiver) Operating manual, firmware 1.02_000, 01-May-2025 QMX operating manual; firmware 1_02_000...
  • Page 2 NOTE: This operating manual applies to both QMX and QMX+ transceivers. There are very few differences between the transceivers and they run the same firmware. Differences are identified in this manual. Elsewhere the terms “QMX” and “QMX+” can be used interchangeably.
  • Page 3 8.7 PC and CAT menu.............................118 8.7.1 System config..............................119 8.7.2 Input Analysis..............................119 8.7.3 CAT command test............................123 8.7.4 CAT monitor..............................129 8.7.5 Log file................................129 8.8 System menu..............................132 8.8.1 CPU Monitor..............................132 8.9 Exit terminal..............................133 9. Resources................................134 10. Document Revision History...........................134 QMX operating manual; firmware 1_02_000...
  • Page 4 Overview of features QMX is a high performance, 5 or 6-band multi-mode 5W QRP transceiver kit, which implements a sophisticated SDR receiver in a 168MHz 32-bit ARM Cortex M4 microcontroller (STM32F446). Most of the features are implemented digitally in firmware, and the feature set is continuing to be expanded by ongoing firmware development.
  • Page 5 A real-time clock can be displayed at the bottom right of the LCD. The time can be set by connecting a GPS receiver such as the QRP Labs QLG2 temporarily to the QMX. When power is disconnected from the QMX, the time is lost and will start at 00:00 at next power-up.
  • Page 6 GPS Interface The QMX kit has a GPS interface, which is used for calibration, setting the real time clock, and for frequency and time discipline and locator setting during WSPR operation. The GPS interface (1pps and 9600 baud serial data) shares the same pins as the paddle dit and dah signals (necessary due to limited processor I/O).
  • Page 7 Here the 1pps signal from the GPS must be connected to the 3.5mm jack “tip” connection, and the serial data (9600 baud) to the “ring” connection. In QMX these signals are 3.3V logic level; however they are connected to 5V-tolerant I/O pins on the microcontroller so 5V logic level will also work fine.
  • Page 8 Note that the QMX cannot supply +5V to the GPS module power supply, and in this regard the GPS interface differs from that of the QRP Labs QCX-series transceivers. So you need to arrange a separate 5V power supply for the QLG2 GPS (for example).
  • Page 9 Additionally they may be configured to also be active during receive – which may be used to control some external switching for example. Note that the two outputs have 220-ohm resistors in series, to protect internal QMX circuits in the case of short-circuits.
  • Page 10 QMX+ connections This is the rear panel of QMX+. The RF, USB, PTT and DC connectors are exactly the same as described in the section above. The Paddle/Mic and Earphones connectors are on the QMX+ front panel (see below). Additionally there are two further connectors:...
  • Page 11 If the practice mode was caused automatically as a self-protection, by plugging in the GPS into a QMX (paddle port), a ‘G’ is displayed. ‘M’ During saved message transmissions, this character is set to ‘M’...
  • Page 12 HH:MM format; it can be set manually or via GPS serial data stream parsing (UT). 4. Operator Controls This diagram shows the operating controls of the QMX. There are two rotary encoders at left and right, and two push-buttons in the center. The main function of the left rotary encoder is Volume adjustment, and that of the right rotary encoder is Tuning.
  • Page 13 The front panel of the QMX+ has the same controls but they are arranged differently in a Desktop transceiver format, as opposed to QMX where the controls are on the top face of the unit which is more suitable for portable operations.
  • Page 14 Not only does it avoid any potential intermittent connections but it also saves the current state of your transceiver (which mode you are in, which band you are on, operating frequency, etc) such that next time you power up, your QMX will be in the same state. Operating mode A single press of the left encoder button cycles through the available operating modes, for example Digital, CW, etc.
  • Page 15 1kHz and 10Hz steps, you can set that up. To cancel RIT tuning (reset the RIT to zero), press the “Exit” button; this returns to main operating mode and sets the RIT to zero. QMX operating manual; firmware 1_02_000...
  • Page 16 The presets are labelled 1 to 16, and can be individually edited in the Preset menu (see later). Often it is more convenient to just save them from the current VFO frequency. QMX operating manual; firmware 1_02_000...
  • Page 17 Messages menu (see later description). The interval between the repeated transmissions is also defined in the Messages menu, in the “Interval” parameter. Once you have selected the message that you want to transmit, press one of the three buttons as follows: QMX operating manual; firmware 1_02_000...
  • Page 18 NOTE that changes to configuration parameters in most cases only take effect on the radio, when you leave the menu system and return to the main operating mode. During viewing or editing of menu items, the radio remains in receive mode on the currently selected VFO frequency. QMX operating manual; firmware 1_02_000...
  • Page 19 Saving current operating parameters (VFO frequency etc) When you power down QMX by pressing the VOL knob, the display will show “Shut down” briefly before powering down QMX. At this time, various important operating conditions of the transceiver are stored in non-volatile storage (EEPROM) that is retained while the power is off. Next time you...
  • Page 20 The cursor starts at the far left (most significant digit). The TUNE knob adjusts the selected digit. The operation is very similar to tuning a VFO in ordinary operation. This example shows editing the beacon frequency, in the beacon menu: QMX operating manual; firmware 1_02_000...
  • Page 21 It is also possible to edit a text parameter entirely with the buttons and rotary encoder, though this is usually a slower way to edit text parameters. Owners of the QRP Labs Ultimate3S (or earlier) QRSS/WSPR transmitter kits will already be familiar with this style of editing text.
  • Page 22 40, 60, 80 or 100dB. The default is 0dB. This may be used to reduce the gain if you are using sensitive headphones for example, and you find that the minimum volume setting is still too loud. QMX operating manual; firmware 1_02_000...
  • Page 23 Ordinarily Morse dit and dah durations have a 1:3 ratio. The space between symbols is equivalent to 1 dit, between characters 3 dit lengths, and between words 7 dit lengths. This is standard Morse timing. However, some people may wish to alter this, for various reasons. QMX operating manual; firmware 1_02_000...
  • Page 24 (or any QRM, QRN etc) transmitting in between the dits and dahs of your own transmissions. Many experienced operators like to be able to have a feel for what is happening on the band, in QMX operating manual; firmware 1_02_000...
  • Page 25 RF power to the antenna! During practice mode, a ‘P’ is shown in the display to the right of the frequency on the top row. QMX operating manual; firmware 1_02_000...
  • Page 26 GPS protection ENABLED If QMX detects a GPS receiver has been plugged into the paddle port, it will automatically set up a temporary “Practice mode” (if practice mode is not already enabled) so that the radio is not continuously keyed by the incoming GPS serial data and 1pps. A ‘G’ character appears in the display to the right of the frequency on the top row (where the ‘P’...
  • Page 27 This can be particularly offensive in some contest or pileup situations where exchanges are very short. Ampl. Avg. QMX operating manual; firmware 1_02_000...
  • Page 28 Prefer prosigns This parameter resolves any ambiguity between punctuation and prosign characters. When switched to YES, the prosigns will be shown. When switched to NO, the punctuation is shown. QMX operating manual; firmware 1_02_000...
  • Page 29 CW Filters QMX has two CW filters, which have 300Hz and 500Hz bandwidths. Each of the two filters has a choice of center frequencies: 300Hz bandwidth: centers 500, 550, 600, 650, 700, 750, 800, 850, 900 and 950hz •...
  • Page 30 The CW settings (filter settings) menu is pictured (right) and all the configuration parameters are available either under terminal login (pictured) or on the QMX LCD/buttons itself, as described in the following pages. CW passband Selects the CW passband. The available options are None, 50, 100, 150, 200, 250, 300, 400 and 500 (Hz).
  • Page 31 CW passband (see previous section description). Auto-offset/tone When this parameter is YES, the CW Offset and Sidetone frequency parameters are automatically adjusted when the CW filter is changed, to match the center frequency of the chosen CW filter. QMX operating manual; firmware 1_02_000...
  • Page 32 CW offset Sets the CW reception offset. The CW filter in QMX is a 300Hz wide filter centered on 700Hz. By default the CW offset is therefore 700Hz, to place the received signal in the middle of the CW filter.
  • Page 33 When the audio stops, QMX will switch back to Receive automatically. The problem with this is that any system sounds on your PC, if the PC is configured to deliver these to the QMX USB sound card, will operate the transmitter and be transmitted.
  • Page 34 If using VOX, you will also need to disable the CAT timeout feature (see below). The Voice Operated Transmit (VOX) function is not normally used. Normally you will wish to connect WSJT-X (for example) via CAT to the QMX Virtual COM serial port. Rise threshold This is a percentage signal level of maximum, above which the transmitter will be keyed down (switched on).
  • Page 35 This parameter is used in conjunction with the QMX operating manual Minimum samples parameter: both conditions must be satisfied in order for an audio frequency measurement to be completed. This parameter is discussed further in the Design section of this manual in the Audio Frequency Analysis section.
  • Page 36 LSB and USB. 5.11 SSB menu The SSB menu contains all the configuration parameters necessary for configuration of the QMX SSB functionality. Transmit EQ submenu The Transmit EQ screen contains configuration settings for a parametric equalizer. There are two filters, for bass and treble response;...
  • Page 37 0.1 and you press the left or right arrow buttons to increase or decrease the slope (turn rotary encoder on the QMX front panel). Note that for very steep slopes > 1.0, the response will slightly overshoot the x-axis (zero).
  • Page 38 2.0 in steps of 0.1 and you press the left or right arrow buttons (or rotate the Tune rotary encoder, on the QMX itself) to increase or decrease the slope. Note that for very steep slopes > 1.0, the response will slightly overshoot the x-axis (zero).
  • Page 39 2700 Filter RX: The filter bandwidth used for SSB reception. Available values, selected with the Left/Right arrow button in the terminal, or the Tune rotary encoder on the QMX, are: 2500, 2700, 2900 or 3200 Hz. QMX operating manual; firmware 1_02_000...
  • Page 40 DC level elimination. Available values, selected with the Left/Right arrow button in the terminal, or the Tune rotary encoder on the QMX, are: 2500, 2700, 2900 or 3200 Hz. Input Ext.
  • Page 41 Peak Envelope Power. It was audible to me during testing because I transmitted at 5W PEP from a QMX+ into 79dB of inline BNC attenuators, straight into a QDX acting as the receiver. At the QDX input that results in an S9 + 30dB signal! Meanwhile there is no band noise, because the QDX (as receiver) RF port is piped straight to the QMX+ (as transmitter) RF port via BNC attenuators.
  • Page 42 1. When it reaches zero, the transmitter is switched OFF by disabling the driver. In this way, samples slows down the gating, creating a kind of hysteresis which prevents rapid crackling occurring by too many on/off gate actions. QMX operating manual; firmware 1_02_000...
  • Page 43 In the QMX the audio source can be the USB sound card, so the VOX settings also apply to the USB sound card audio, if USB is selected as the Input source for the SSB transmitter. The VOX subsystem operates in parallel with the PTT button, and indeed the CAT commands.
  • Page 44 12W (for example). For single tone (CW), two-tone transmissions, FSK Digi modes, and some others, CESSB does not provide any improvement. It is primarily a technique for improving average to peak power on Speech transmissions. QMX operating manual; firmware 1_02_000...
  • Page 45 QMX stores a phase pre-distortion curve of phase error vs amplitude, for each band of operation. These curves are measured by QMX using the Calibration tool later in this manual. If Phase pre- distortion is ON and Calibration has not been run, it will have no effect (because the calibration curves are zero).
  • Page 46 A delay in milliseconds, between when PTT is pressed and when transmission actually starts. Correspondingly on releasing the PTT switch to cease transmission, the SSB transmission stops then the system waits this number of milliseconds before switching QMX back to Receive mode. 5.12 Frequency presets menu There are 16 frequency presets, labelled 1 to 16.
  • Page 47 Interval The Interval is a NUMBER parameter that specifies the interval in seconds, between repeated transmission of a stored message (if repeats are configured: see next parameter). QMX operating manual; firmware 1_02_000...
  • Page 48 Note that if no VFO modes are enabled, on pressing the right button to change VFOs, the system automatically enables all three VFO modes, so that we are never left in a situation where no VFO modes are enabled. QMX operating manual; firmware 1_02_000...
  • Page 49 VFO and RIT tune rates are available in the terminal also; in the example (right) the RIT tuning rates 1kHz and 10Hz are switched on, which means pressing the Tune knob will cycle between these two RIT tune rate values. QMX operating manual; firmware 1_02_000...
  • Page 50 CW, QRSS, DFCW, FSKCW, Hellscreiber (full speed and slow FSK), WSPR, JT9, JT65, ISCAT, Opera and PI4. The vast majority of people use the Ultimate3S kit for WSPR operation. Since it costs nothing (no extra hardware, at least) to add this functionality to the QMX transceiver, why not! Let’s do it! The CW transceiver beacon function therefore contains a simplified WSPR implementation which can transmit standard WSPR messages.
  • Page 51 On a PC spectrum display such as the Argo software http://www.weaksignals.com/ WSPR messages look something like the screenshot below when received locally (or usually worse, because you probably are over-driving your receiver when receiving your own signal!): QMX operating manual; firmware 1_02_000...
  • Page 52 “Practice mode” where no RF is produced. Beacon mode is entered upon leaving the configuration menu system, if the beacon is enabled by having this parameter set to a value other than OFF. QMX operating manual; firmware 1_02_000...
  • Page 53 200Hz sub-band. QMX uses a 25MHz TCXO reference which is normally within a few Hz, so accuracy of the transmission frequency is not normally an issue, even with no calibration.
  • Page 54 The Locator is the second parameter which is encoded into the WSPR message. It is the 4- character Maidenhead square. The text you enter here, must be a valid Maidenhead square, otherwise an error message will be generated on exiting the configuration menu system. QMX operating manual; firmware 1_02_000...
  • Page 55 Battery display sub-menu The parameters that control the battery voltage display are contained in this sub-menu. Enable QMX operating manual; firmware 1_02_000...
  • Page 56 The power meter shows in the three meter characters to the right of the mode indicator, with a range from 0 to 6W, each pixel column is equivalent to 0.4W. The SWR meter is shown in the QMX operating manual; firmware 1_02_000...
  • Page 57 It is independent of volume setting. The default values should be approximately correct but there is some dependence on the band pass filter adjustments etc. The range of the S-meter is therefore S0 (-127dBm) to S9+36dB (-37dBm). QMX operating manual; firmware 1_02_000...
  • Page 58 AGC display When ON, and if the “AGC dB per bar” parameter is non-zero, the S-meter display is split into two bars; the lower bar shows the applied AGC attenuation. See above for full description. QMX operating manual; firmware 1_02_000...
  • Page 59 Note that this setting only affects the cursor that is shown during menu system editing. In normal operating mode, the underline cursor is always used for tuning rate indication, regardless of the Cursor style setting. QMX operating manual; firmware 1_02_000...
  • Page 60 When set to ON, a real time clock is displayed in the bottom right part of the screen during operation. The time is NOT maintained when the QMX is powered down. You may set the clock by connecting a GPS such as the QRP Labs QLG2, or in the Set time parameter which is in the Beacon menu or System config menu.
  • Page 61 Remember that there is a square law relationship between RF power output and PA voltage. The default Tune PA voltage of 50% means that the RF power output will be one quarter (25%) the full power value. QMX operating manual; firmware 1_02_000...
  • Page 62 Display/controls menu. Min voltage The minimum supply voltage for the range check enabled by the Supply voltage protection. Max voltage The maximum supply voltage for the range check enabled by the Supply voltage protection. QMX operating manual; firmware 1_02_000...
  • Page 63 Band version 80-20m Displays the band version of your QMX. You will have selected this at first power-up of your QMX. You can change it in this menu but the Band Configuration and other parameters will not be changed to reflect it; if you have chosen the incorrect band version at power-up and wish to reset the configuration appropriately for the version you built, the best way to do this is using the Factory Reset feature.
  • Page 64 To use these tools, simply use WSJT-X and QMX to operate as a 20m WSPR reporter (receiver) for several minutes, then look at this page: https://qrp-labs.com/images/wsprnet/rxerror.html Look for your callsign in the list, which shows the error in your reception reports (operating frequency error).
  • Page 65 All active ports can be used equivalently either for terminal access or for CAT commands. If you select 3 serial ports, QMX makes use of a trick that I discovered which I am calling “ghost endpoints”. Basically the STM32F446 only has 6 endpoint pairs – these are the buffers by which USB communication occurs.
  • Page 66 QMX as an SDR front end, with PC SDR software to demodulate I and Q channels. QMX to transmit and receive CW as normal; only the raw I and Q signals are streamed over the USB interface so that you may use PC SDR software as a panadapter for example.
  • Page 67 Selecting this (by pressing the left button) enters the Advanced configuration sub-menu. Ordinarily you should not need to change anything in this menu, and doing so may damage your QMX! It is highly recommended NOT to change anything in the Anvanced configuration sub-menu unless you really understand the consequences of your actions.
  • Page 68 I am grateful to John Dzbrozek KJ4A for suggestion this feature as a result of his PA simulations and subsequent theoretical analysis. If you select “DISABLE” for this feature it will not damage your QMX but it may not optimize Receiver performance.
  • Page 69 Rev 2 PCBs. It is described in this forum post: https://groups.io/g/QRPLabs/message/113662 and you are recommended to read this if interested. Disabling this feature, particularly on an 80-20m Rev 2 (and above) QMX PCB, is REALLY NOT RECOMMENDED. 5.19...
  • Page 70 The number at the bottom left indicates the measured image rejection, 75.4dB in this case. Note that image rejection varies wildly from one QMX to another, and on different bands, so do not worry particularly about whether it is lower or higher, unless you are using this as a diagnostic to track down a suspected problem.
  • Page 71 LCD version of the LPF sweep terminal tool (described more fully later in the terminal applications section). The Low Pass Filter response is generated by sweeping the QMX operating frequency while transmitting (at reduced power) internal signal generator across the BPF and measuring the signal amplitude.
  • Page 72 Run entire calibration (all screens) Exit button: Exit the SSB calibration tool Tune encoder: Select the calibration result to view (3 types, and all configured bands) Tune enc. button: Run or re-run one calibration screen, the current one QMX operating manual; firmware 1_02_000...
  • Page 73 When started (press the select button) you can speak into an external microphone you have plugged into the QMX. The audio level is sampled 10x per second and displayed in the chart on the right ¼ of the QMX LCD. Gain can be adjusted with the Tune rotary encoder.
  • Page 74 Shows the live realtime state of the CW paddles if you have plugged them in. When a paddle is closed, the corresponding row of the display will show “Pressed”. Note that if your paddle dit and dah appears to be swapped, you can configure that (swap back) in the Keyer menu, QMX operating manual; firmware 1_02_000...
  • Page 75 Number of satellites being tracked. t is for "tracked". Here, 21 satellites are being tracked. • Average signal strength of tracked satellites. s is for "Signal". In this example, it is 36 dB. • 51 30.08321 0 08.96731 Latitude and longitude. Grid IO91FE 23.749 The grid subsquare and altitude. QMX operating manual; firmware 1_02_000...
  • Page 76 Factory reset takes a few seconds while the entire EEPROM contents are written. 5.21 Update firmware This menu item can be used to reboot QMX in the bootloader mode, activating the QRP Labs Firmware Update procedure (QFU). Again it is implemented as a two-step process. Update firmware Sure? Click Tune After pressing the Select button to activate the firmware update, the screen will ask you if you’re...
  • Page 77 Feel free to skip this theoretical section if you just want to get on with it and try some AGC parameter values. The receiver signal path from the QMX’s antenna port BNC connector to the audio output earphone 3.5mm stereo jack connector is as follows: 1.
  • Page 78 1,500 of these 32-sample blocks processed per second, which is crucial to the understanding of the AGC system. 9. Samples are represented internally in the QMX DSP as floating point numbers. Therefore full resolution and high dynamic range is maintained, unlike some SDR implementation which use 16-bit (or less!) integer representations.
  • Page 79 It is important to understand the chunk time needs to contain enough samples to reliably detect peaks in the frequency of interest. The QMX CW filter is a 300Hz bandwidth filter centered on 700Hz. It therefore passes 550-850 Hz. For the same of round numbers, say we wish to detect peaks on a 500Hz signal.
  • Page 80 Noise filter: The duration of the noise filter, that deletes impulse noise from the signal path without starting the hang timer or rest of the AGC system. The parameter is expressed in units of QMX operating manual; firmware 1_02_000...
  • Page 81 AGC attenuation is shown on the bottom half of the S-meter display. In this example, if “AGC dB per bar” is 3, then the AGC attenuation is 39dB since 13 columns of pixels are shown. This feature is useful for keeping an eye on the AGC action. QMX operating manual; firmware 1_02_000...
  • Page 82 PC and the QMX. Naturally you need a power supply and the antenna connection too. QMX must be set to Digital mode or USB mode, to be able to use the PC and QMX combination for digital modes! Press the VOL knob to change the mode on QMX.
  • Page 83 These commands are similar as used for Modem Manager service. WSJT-X configuration Next it is necessary to set up WSJT-X to communicate with QMX. We will use WSJT-X as the example, because it will be what most people are using. But other software will be identical (for example JS8Call) or similar.
  • Page 84 Unfortunately unlike the USB Sound, the serial port name doesn’t contain the text “QMX”. If you are unsure which port to choose for QMX, the easy way to find this is as follows. Unplug QMX. Restart WSJT-X. Look in Settings -> Radio and make a note of the list of serial devices.
  • Page 85 With PTT Method set to CAT, when WSJT-X wishes to start a transmission, it will send an actual CAT command to QMX informing it to start the transmission, before sending the audio. This CAT command causes QMX to switch from Receive mode to Transmit mode (and back again afterwards).
  • Page 86 QMX using CAT commands that are not supported by QMX. In the section of this manual on the CAT Test utility (in the QMX Terminal applications), you will find a listing of the CAT commands supported by QMX. Another useful utility is the log file, which will let you record all CAT commands received and investigate any issues.
  • Page 87 QMX has no such LED. However, QMX has an indicator on the top left character of the LCD, under the ‘A’ symbol of VFO Note that the transceiver must be put into DIGI mode before attempting digital transmissions from WSJT-X otherwise they’re just ignored.
  • Page 88 QMX will show you the master volume level, and it needs to be set to 100% (not more, not less). There’s a similar thing on Windows OS.
  • Page 89 This QMX manual is not the place to include tutorials on various digi mode operation or particular application software such as WSJT-X, such guides are readily available and written very much more thoroughly than I could hope to achieve! Firmware Update procedure On occasion QRP Labs may make available updated firmware for QMX, in order to deliver bug fixes or functionality enhancements.
  • Page 90 EEPROM contents: the QMX configuration and log file (if enabled). Again, you can read the file from QMX or write a new one to QMX, simply by dragging files in your file manager application.
  • Page 91 Or copy and paste it, however you wish. The file on the QRP Labs website is a ZIPPED file, please be sure to unzip it to get the .QMX file before copying it to QMX.
  • Page 92 The QMX firmware is 256-bit AES encrypted and this means: The encrypted QMX firmware file will 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 Labs •...
  • Page 93 Make sure WSJT-X is NOT running, when you connect to the QMX serial port using the terminal emulator. Only one PC application at a time can connect to Virtual COM Serial ports. Set the size of the terminal window to 80 columns and 24 rows.
  • Page 94 CAT command mode, use the cursor keys to scroll down to the “Exit terminal” option at the bottom of the main menu, and press Enter. The screen is now cleared, and QMX is back in CAT command mode. Only then should you close the terminal emulator window.
  • Page 95 Note that entering the Configuration menu in the terminal locks out the Configuration menu on the QMX LCD, and vice versa. Furthermore, in general, as per the configuration menu on the LCD, configuration parameters do not take effect until you leave the Configuration menu system.
  • Page 96 Low Pass Filter during transmit. The adjustment range is 5 to 60mA. The default value is 30mA and should generally be left alone. Transmit: Enabled or Disabled, to allow or prevent transmission on this band. Press the E key to enable, D key to disable. QMX operating manual; firmware 1_02_000...
  • Page 97 Remember, the 50W PA is a SINGLE BAND amplifier so should only be used on the QMX with a single band, unless you are going to build an external switched Low Pass Filter. Also remember that the 50W QCX-series amplifier is designed for CW operation and not suitable for the high duty cycle of digital modes;...
  • Page 98 The following is the default Band Configuration screen for the QMX+ 160-6m version: QMX operating manual; firmware 1_02_000...
  • Page 99 50 Hz steps up to and including 3850 Hz. The RF frequencies (“USB Dial Frequency”) used for bands are defined in the Band Configuration screen of the QMX. For example, for 80, 40, 30 and 20m are 3.573, 7.074, 10.136 and 14.074 MHz respectively. The vertical axis shows audio decibel (dB) level.
  • Page 100 8.6.2 RF filter sweep QMX contains its own internal signal generator, which can be used to sweep the receiver input Band Pass Filters, checking its response and center frequency. Though the difference in performance is small, the perfectionist may wish to adjust (by squeezing turns) the Band Pass Filter inductor L401 to optimize the center frequencies of the filters.
  • Page 101 The following screenshots show typical performance, which may vary from device to device. Do not worry that 60 and 80m are not peaked; sensitivity is less of an issue anyway on low bands. QMX operating manual; firmware 1_02_000...
  • Page 102 The following images show reasonable RF sweep curves for the 20-10m version: QMX operating manual; firmware 1_02_000...
  • Page 103 The following images show reasonable RF sweep curves for the 60-15m version: QMX operating manual; firmware 1_02_000...
  • Page 104 Any phase error in the 90-degree quadrature relationship • In QMX to date, no attempt is made to compensate for these errors. The image rejection has been found to be adequate without it. A future firmware version will likely include automatic adjustments to improve image rejection.
  • Page 105 “Tune %” parameter in the Protection menu. Remember that due to the square-law relationship between voltage and power, when the voltage is halved the power output is one quarter of full power. If the power is too low, the SWR measurement will be QMX operating manual; firmware 1_02_000...
  • Page 106 The filter shape displayed here should be taken with a pinch of salt; it’s not going to be super accurate; but may suffice for some fault-finding assistance or general education about the design and operation of the radio. It is also important to note that the minimum level of about -35dB QMX operating manual; firmware 1_02_000...
  • Page 107 The PA amplitude modulator test screen increases the DAC voltage applied to the amplitude modulator (X-axis) while measuring the resulting voltage supplied to the PA (Y-axis). It should be a very straight line going from near the bottom corner, to near the positive supply voltage. QMX operating manual; firmware 1_02_000...
  • Page 108 QMX/QMX+, as follows: 1. The band is set to the first column (Band Index = 0) of the Band Configuration table for QMX, and the second column (Bnad Index = 1, 80m) of the Band Configuration table for QMX+. 2. A test signal is generated at a 750Hz offset to the band’s defined Center Frequency and injected into the RF front end (the same as done for RF Sweeps).
  • Page 109 QMX can measure the phase distortion of its own power amplifier. The calibration tool can be viewed to view existing calibration results or run the calibration itself. There are three kinds of calibration, each one runs for all transmit-enabled bands on your QMX: Phase error measurement for phase pre-distortion •...
  • Page 110 CW). These tests are NOT more stressful to QMX than ordinary FT8 transmissions for example. Note that if you do not run these calibration steps, the QMX SSB transmission will still work well. The calibration just improves it even further.
  • Page 111 Band Pass Filters to see if any can be used, and if so, which is optimum for the measurement. The list of filters numbered 0 to 7 applies to QMX+ (for QMX, the filters would be numbered 0 to 3).
  • Page 112 1/3rd the transmit frequency; in these cases the calibration is abandoned and zeroes are written as the phase error. The calibrations can also be run from the QMX LCD, please refer to the earlier section on this topic.
  • Page 113 In a quiet room, with no sounds, a screen like this is approximately correct (good enough sensitivity), when the gain is set such that on speech peaks the bars just about stray into the red territory. QMX operating manual; firmware 1_02_000...
  • Page 114 In the left image, the mic gain is much too low. In the right image, the gain is much too high. The microphone test tool is also available on the QMX LCD but is a lot harder to judge on the small 20 x 16 pixel scrolling display area.
  • Page 115 Controls You can test all the controls of the QMX here; the four buttons (including the two on the shafts of the rotary encoders), and the clockwise/anticlockwise operation of the rotary encoders (indicated as >>> and <<< respectively). When you open the hardware diagnostics testing screen the six rows are all red;...
  • Page 116 (3.3V and 5V power rails) and switches off the linear 3.3V regulator. IF there is a fault on any of this, QMX will not start; it will not start the receiver or transmitter, and will not power the LCD module or write anything to the LCD.
  • Page 117 The "GPS Viewer" application is also available in the "Hardrware tests" sub-menu on the LCD/buttons/rotary encoders of the QMX itself, and contains three screens which you can scroll through by turning the right encoder. They show a general information summary screen, a Latitude/Longitude screen, and a screen showing Grid subsquare and Altitude.
  • Page 118 PC and CAT menu This menu contains several items related to the PC interface and CAT commands. QMX operating manual; firmware 1_02_000...
  • Page 119 8.7.2 Input Analysis The Input analysis application is one of the most interesting screens in the QMX Terminal application suite. It shows a “waterfall” which scrolls upward, with the measured audio frequency shown as a yellow block in each row, with its horizontal position determined by its frequency. The scroll rate, and the screen width, are adjustable.
  • Page 120 Display elements This annotated screenshot illustrates the various elements on the display. The display elements on the top row are: QMX operating manual; firmware 1_02_000...
  • Page 121 Update vertical Matching Comment rate (ms) Div (s) mode Only display “10ms” in top left Only display gridlines and “20ms” in top left JT65 WSPR QMX operating manual; firmware 1_02_000...
  • Page 122 Div (Hz) Demonstration of sliding frequency changes A fun and useful demonstration of the capabilities of QMX and the Input Analysis application, is to investigate the FT8 tone change transition. We know according to the WSJT-X documentation that to avoid splatter onto adjacent frequencies, WSJT-X makes a smooth transition between one tone symbol and the next.
  • Page 123 We’re talking here about tradeoffs in different aspects of performance; either way the performance is excellent and QMX keeps up with the changes in input frequency! So this is a nice confirmation of the excellent performance characteristics of QMX.
  • Page 124 QMX, and is old enough that it is widely supported by most software packages. Additionally QMX provides an extended set of CAT commands Q0, Q1, Q2 and so on until QB. These commands allow a host program to set and get various configuration parameters of QMX.
  • Page 125 Set VFO Mode: 0, 1, 2 correspond to VFO A, VFO B or Split respectively. This is the case for both the FR and FT commands (which are nominally Receive and Transmit VFOs) because in the QMX the VFO mode use does not correspond exactly to TS-480. Get: Get Transmit VFO Mode: 0 means VFO A is used for transmit (must be VFO Mode A);...
  • Page 126 EEPROM. Get: Get sideband; 0 = USB, 1 = LSB Q2: Get/Set VFO A frequency – same as FA Set: Set default operating frequency. Get: Get default operating frequency. QMX operating manual; firmware 1_02_000...
  • Page 127 Set Japanese Band Limits mode: 1 enables Japanese band limits, 0 disables Japanese band limits. In Japanese Band Limits mode, QMX cannot transmit outside the allowed Japanese band limits. The setting is for the current operating session only and is not written to EEPROM.
  • Page 128 Returns the S-meter value in dB. SP: Get/Set Split mode Set: Sets Split mode: 0 = OFF, 1 = ON. For example “SP1;” switches QMX to split mode Get: Returns the Split state: 0 = OFF, 1 = ON. QMX operating manual; firmware 1_02_000...
  • Page 129 The CAT command monitor is a very plain blank screen, whose only purpose is to scroll incoming CAT commands from the CAT host, and the QMX responses. You will only be able to use this screen if you have multiple serial ports connected – one (typically the main USB Virtual COM port) to the PC host and one to a terminal (or terminal emulator on a PC, via a USB-Serial converter), running the CAT monitor terminal application.
  • Page 130 ERR: Band Error message “Band” In this example, a CAT command was received from WSJT-X, to set the QMX to frequency 1.84 MHz. The CAT command is “FA00001840000;” - Note that the entries in the log file are not quite in chronological order, since the VFO update event is printed BEFORE the CAT command event;...
  • Page 131 The operator then realizes his error setting QMX to 160m in the WSJT-X drop-down and chooses 40m instead; this time the CAT command successfully sets frequency and band. IF; IF00007074000 +00000000003000000 ; Here the “IF;” or Information request CAT command is received from WSJT-X and QMX replies with the CAT information string in the prescribed format.
  • Page 132 Please refer to the section of this manual describing the firmware update procedure. 8.8.1 CPU Monitor The CPU Monitor tool records the activity of the processes in the QMX operating system, in two ways: Number of times each process is called per second •...
  • Page 133 Exit terminal As mentioned previously, exit terminal returns QMX to normal operating mode, processing incoming CAT commands as usual. The terminal should also be disconnected (or closed) so as to free up the serial port for use by WSJT-X or whatever software you are using –...
  • Page 134 Resources For updates and tips relating to this kit please visit the QRP Labs QMX kit page http://qrp-  labs.com/q m x For any questions regarding the assembly and operation of this kit please join the QRP  Labs group, see http://groups.io/g/qrplabs...