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QRP Labs QDX Operating Manual

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QDX
QDX: QRP Labs Digital Xcvr (transceiver)
Operating manual, firmware 1.04
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QDX operating manual; firmware 1_04

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Summary of Contents for QRP Labs QDX

  • Page 1 QDX: QRP Labs Digital Xcvr (transceiver) Operating manual, firmware 1.04 QDX operating manual; firmware 1_04...

  • Page 2: Table Of Contents

    4.7 RF filter sweep..............................22 4.8 Input analysis...............................23 4.9 CAT command test..............................27 4.10 Log file................................32 4.11 Transmitter test..............................35 4.12 Factory reset..............................36 4.13 Update firmware...............................36 4.14 Exit terminal..............................36 5. Troubleshooting Transmit issues..........................36 6. Resources.................................. 38 7. Document Revision History............................38 QDX operating manual; firmware 1_04...

  • Page 3: Introduction

    This document describes operation of QDX, and applies to the firmware version specified. This manual will get you started with QDX and your WSJT-X or other digi modes software in minutes. PLEASE READ THE BASIC ASSEMBLY AND USE INSTRUCTIONS IN...

  • Page 4: Operating Instructions

    Not least because when QDX receives a carriage return character, it will enter Terminal Applications mode; this will send all sorts of characters back to the PC (as QDX thinks it is now talking to a terminal emulator) and it will disable CAT command processing, so your PC digi modes software will not be able to talk to QDX.
  • Page 5 WSJT-X configuration Next it is necessary to set up WSJT-X to communicate with QDX. 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. There are two parts to the set-up – firstly to choose the right USB Sound card, and secondly to set up the CAT communication so that WSJT-X can control the QDX via the serial comm port.
  • Page 6 I feel more comfortable with the less frequent polling. QDX has no capability to alter its operating frequency for example by itself, it can only do so at the command of WSJT-X over CAT; therefore the polling is actually redundant anyway.
  • Page 7 QDX using CAT commands that are not supported by QDX. In the section of this manual on the CAT Test utility (in the QDX Terminal applications), you will find a listing of the CAT commands supported by QDX. Another useful utility is the log file, which will let you record all CAT commands received and investigate any issues.
  • Page 8 PC, is when the Pwr is at the maximum setting. There is no point to using any setting other than maximum, because QDX only ever transmits at full power (5W), there is no way for it to transmit at a lower power output under command of WSJT-X.
  • Page 9 QDX Status LED The front panel of QDX contains a 3mm red Status LED. The operation of this LED is as follows: Quick flashing (flickering) for first 5 seconds after power up: if you disconnect power now, • then next time you power up, QDX will be in firmware update mode. During this five seconds QDX is also operating normally in Receive mode.

  • Page 10: Firmware Update Procedure

    QDX provides two possible ways to enter firmware update mode: 1) On powering up QDX, you will see the QDX status LED flickers quickly for 5 seconds after power up, then illuminates solidly. If you power down QDX during this 5 seconds, then apply power again, QDX will now boot up in QFU (Firmware Update) mode.
  • Page 11 EEPROM contents: the QDX configuration and log file (if enabled). Again, you can read the file from QDX or write a new one to QDX, simply by dragging files in your file manager application. On entering the Firmware update procedure, a pop-up window should appear on your PC. On my system (Linux XUbuntu 18.04) it looks like this:...
  • Page 12 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 .QDX file before copying it to QDX.

  • Page 13: Terminal Applications

    I start PuTTY using command line “sudo putty” then connect to QDX on /dev/ttyACM1. Again as before (refer to the Operating Instructions for connecting to QDX using CAT on WSJT-X) it is necessary to know which serial port is being used by QDX. There is also a guide to identifying the serial port at http://qrp-labs.com/qlg2...

  • Page 14: Entering Terminal Applications Mode

    CAT command mode, use the cursor keys to scroll down to the “Exit terminal” option at the bottom of the list, and press Enter. The screen is now cleared, and QDX is back in CAT command mode. Only then should you close the terminal emulator window.

  • Page 15: Configuration

    For non-numeric configuration parameters, you can use the left and right arrow keys to choose between the available values. TCXO Frequency Default is 25000000 (25 MHz). This is the oscillation frequency of the QDX TCXO (Temperature Controlled Crystal Oscillator) and is used for calculating Si5351A parameters for setting the desired QDX operating frequency.
  • Page 16 QRP Labs website to help you to use the WSPRnet reporting network to determine your operating frequency quite accurately. To use these tools, simply use WSJT-X and QDX 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 17 When the audio stops, QDX 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 QDX USB sound card, will operate the transmitter and be transmitted.
  • Page 18 This is suitable for people wishing to experiment with using QDX as an SDR front end, with PC SDR software to demodulate I and Q channels. Remember that there is a 12kHz IF offset applied to the VFO.

  • Page 19: Band Configuration

    The Band Configuration screen allows specification of all parameters that are handled per-band. This screen is populated by default with the correct information to set QDX up for 5-band operation on 80, 60, 40, 30 and 20m. However, if you wish to experiment with other bands (which will require hardware modifications to Receiver Band Pass Filter and Transmitter Low Pass Filter component values –...
  • Page 20 50W Power Amplifier with a simple stereo jack audio cable. Remember, the 50W PA is a SINGLE BAND amplifier so should only be used on the QDX 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 21: Audio Filter Sweep

    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 QDX. 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 22: Rf Filter Sweep

    4.7 RF filter sweep QDX 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 L12 to optimize the center frequencies of the filters.

  • Page 23: Input Analysis

    4.8 Input analysis The Input analysis application is one of the most interesting screens in the QDX 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 24 At 20ms per row (50 row updates per second) the only text on the display is “20ms” in the top left corner; the grid lines are still displayed. At 10ms (100 row updates per QDX operating manual; firmware 1_04...
  • Page 25 Only display gridlines and “20ms” in top left JT65 WSPR Horizontal size (Hz): The available horizontal screen size (selected by the left/right arrow keys) are chosen to cleanly fit the 80 columns display width. Screen Horizontal width (Hz) Div (Hz) QDX operating manual; firmware 1_04...
  • Page 26 We’re talking here about tradeoffs in different aspects of performance; either way the performance is excellent and QDX keeps up with the changes in input frequency! So this is a nice confirmation of the excellent performance characteristics of QDX.

  • Page 27: Cat Command Test

    Here in this simple application, you can type the command (or commands) you wish to send to QDX in the yellow area of the bottom row. If you forget the trailing semicolon, the application adds one automatically for you. Then simply the command is shown in yellow in the left column, and the command result in yellow in the right column.
  • Page 28 VFO B is being used for transmit (could be due to VFO mode being VFO B, or VFO Mode being Split) FW: Get filter bandwidth Get: Always returns 3200 meaning, 3200Hz (the QDX’s filter bandwidth). ID: Get radio ID Get: Always returns 020 (Kenwood TS-480)
  • Page 29 Q3: Get/Set receiver Gain Set: Set receiver gain. The setting is for the current operating session only and is not written to EEPROM. Get: Get receiver gain. The default value on Factory Reset is 5000. QDX operating manual; firmware 1_04...
  • Page 30 Set Japanese Band Limits mode: 1 enables Japanese band limits, 0 disables Japanese band limits. In Japanese Band Limits mode, QDX cannot transmit outside the allowed Japanese band limits. The setting is for the current operating session only and is not written to EEPROM.
  • Page 31 Command RX; immediately puts the radio into receive mode. It is equivalent to TQ0; SP: Get/Set Split mode Set: Sets Split mode: 0 = OFF, 1 = ON. For example “SP1;” switches QDX to split mode Get: Returns the Split state: 0 = OFF, 1 = ON.

  • Page 32: Log File

    CAT commands are shown (semicolon terminated) followed by the command result, if any. • An unrecognized or invalid CAT command would be prefixed by the error code “ERR: “. Radio state changes are indicated by the item being changed, followed by the new value. • QDX operating manual; firmware 1_04...
  • Page 33 ERR: Band Error message “Band” In this example, a CAT command was received from WSJT-X, to set the QDX 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 34 Audio gain is set by the AG; CAT command RIT Down RIT down CAT RIT DN command RIT Up RIT up CAT RIT UP command Every CAT Every CAT command generates a log entry event command QDX operating manual; firmware 1_04...

  • Page 35: Transmitter Test

    So for example, if you have disabled 80m transmit operation, and you have selected the band 80m, then pressing the t key to transmit, has no effect. The frequency chosen for the transmission is just the default FT8 frequency for the selected band. QDX operating manual; firmware 1_04...

  • Page 36: Factory Reset

    Virutal COM Port serial interface, telling QDX to switch to transmit. This will only work if the serial port has been correctly set to the port QDX is on, and if you have selected the correct CAT rig (for example, Kenwood TS-440). VOX is not recommended, but if you have enabled VOX PTT rather than CAT, and QDX does not transmit, it means the sound is not reaching QDX (see the 1-flash and 2-flashes diagnostics below).
  • Page 37 PC audio settings. 2 flashes: QDX is receiving audio from your PC. But the volume is insufficient to trigger the key-down (transmit) action. Remember that there is a “Rise Threshold” setting in the QDX Configuration terminal application, which defaults to 80% of maximum value.

  • Page 38: Resources

    3 flashes If the status LEDis flashing three times, this means that QDX is being correctly commanded to go to transmit mode (the host application activates the PTT CAT command), QDX is detecting and measuring the audio from the PC, and furthermore, the audio is of sufficient level to activate the QDX transmit.

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