The "QDX-M" (QRP Labs Digital Xcvr-Monoband): a feature-packed, high performance, SINGLE BAND Digi-modes transceiver kit, including embedded SDR receiver, 24-bit 48 ksps USB sound card, CAT control, synthesized VFO with TCXO reference. QDX transmits a SINGLE SIGNAL, it is not an SSB modulator with associated unwanted sideband and residual carrier, or intermodulation due to amplifier non-linearity. QDX outputs a pure single signal. 

QDX-M is based on the QDX transceiver but is designed for a single band only, so omits the band-switched filtering. This provides a slight improvement in performance particularly on the higher bands, but it also allows us to offer a version for 160m, 630m and 2200m. The multi-band QDX cannot access these lower bands because the PIN diode band-switching doesn't work at such low frequencies.

QDX-M is suitable only for single tone FSK modes, which covers the majority of digital modes in use today. This includes everything in WSJT-X, JS8Call, some fldigi modes e.g. RTTY, Olivia and more. QDX-M is not suitable for on/off keyed modes such as CW because it does not have click-reducing RF envelope shaping; furthermore it is not suitable for phase shift keyed modes such as PSK31 or modes involving multiple concurrent tones such as WinLink.

FIrmware: The same firmware is used for QDX and QDX-M

Bands: QDX-M will be available eventually for any single band from 2200m to 10m (initially the band selection will be limited; more bands will be added in coming weeks).

10, 11 and 12m version: Note that this is actually ONE kit version. If you purchase one of these, you can use it on all three bands. The only difference, when you choose the operating band, is the position of the band center indicator in the RF screen in the terminal configuration utilities.

Assembled kit: If you choose the assembled option, the kit will be by default, assembled for operation from a 12V supply. If you prefer it to be built for 9V supply operation, please write a note in the customer notes/comments field at the checkout.

The Optional enclosure is black anodized extruded aluminium, very sturdy and elegant. The enclosure size is 89 x 63 x 25mm without protrusions. The front and rear panels are drilled and cut to match the QDX PCB with laser-etched lettering. The enclosure includes four self-adhesive feet. NOTE: The Rev3/3a/4 QDX do NOT fit in the previous QDX enclosure. The rear panel is different - due to the addition of the PTT connector.

List of features: 

  • Single band for any choice of 2200m to 10m (initially, a limited selection)
  • 5W output at 9V supply (can be built for 4-5W at 12-13V supply)
  • Single signal transmission (zero unwanted sideband, zero residual carrier, zero intermodulation distortion)
  • Solid-state transmit/receive switching under CAT control
  • High performance embedded SDR SSB receiver with 60-70dB of unwanted sideband cancellation
  • Built-in 24-bit 48ksps USB sound card
  • Built-in USB Virtual COM Serial port for CAT control
  • Si5351A Synthesized VFO with 25MHz TCXO as standard
  • Easy to build single-board design, Professional quality double-sided, through-hole plated, silk-screen printed PCBs
  • All SMD components factory assembled
  • Connectors: 2.1mm power barrel connector, USB B (for audio and CAT control), BNC RF input/output
  • Built-in test signal generator and testing tools
  • Receive current 100mA, Transmit current 1.0-1.1A for 5W output with 9V supply (around 0.7A for 5W with 13V supply).
  • Optional aluminium extruded cut/drilled/laser-etched black anodized enclosure

Full details, see main QRP Labs QDX-M page

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QDX-M monoband 5W Digi transceiver

  • Product Code: QDXM
  • Availability: 331
  • $65.00

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