µSDX QRP SDR HF Transceiver

Original price was: $248.00.Current price is: $169.00.

The revolutionary µSDX QRP class-E driven SDR HF transceiver puts the world in the palm of your hand! Despite its small size, it covers 9 HF amateur bands from 80 to 10 meters and operates in SSB, CW, and DATA modes.

177 in stock


µSDX QRP SDR HF Transceiver Available options and accessories allow the µSDX QRP SDR HF transceiver to be tailored to your needs, including the optional CW Keyer, Handheld Microphone, Data mode, CAT Control Interface, 100W Power Amplifier, External ATU, and Low Pass Filters Unit. 

The SSB transmit stage is implemented entirely in a digital and software-based manner: at the heart, the ATMEGA328P is sampling the input audio and reconstructs an SSB signal by controlling the SI5351 PLL phase (through tiny frequency changes over 800 kbit/s I2C) and controlling the PA Power (through PWM on the key-shaping circuit). In this way a highly power-efficient class-E driven SSB signal can be realized; a PWM-driven class-E design keeps the SSB transceiver simple, tiny, cool, power-efficient, and low-cost (ie. no need for power-inefficient and complex linear amplifier with bulky heat-sink as often is seen in SSB transceivers).

For the receiver, most parts are implemented in the digital manner (software): The ATMEGA328P is implementing a 90-degree phase shift circuit, the (CW/SSB) filter circuit, and the audio amplifier circuit (now a class-D amplifier). 

This has simplified the µSDX circuit a lot, and there are a number of advantages and features (compared to an analog approach): There is no longer a need for an I/Q alignment procedure due to the very accurate 90-degree Hilbert phase shifter, and there are now adjustable IF DSP filters for CW and SSB.

µSDX QRP SDR HF Transceiver

The µSDX QRP SDR HF transceiver has been created to try out what can be achieved with minimal hardware while moving complexity towards the software; here the approach followed is to simplify the design where possible while keeping a reasonable performance. The result is a cheap, easy-to-use, versatile QRP SSB transceiver that actually is quite suitable for making QSOs (even in contest situations). Whether you’re bagging a new peak on a SOTA outing, pounding out QSOs on Field Day, or working rare DX from the comfort of your home station, your µSDX QRP SDR HF transceiver will provide the features and performance you need.

µSDX QRP SDR HF Transceiver

The µSDX SDR HF transceiver’s unique form factor allows you to operate from anywhere. With a whip antenna, you can even operate hand-held. 

Press the bottom red PTT button to transmit and talk straight to the built-in microphone while holding the radio in your hand. For extreme portability, you can use the optional external wide-range ATU, built-in 12V battery, optional CW keyer, or handheld microphone.

Transmit efficiency is also excellent, further improving battery life. Full-Featured, yet easy to use the µSDX QRP SDR HF transceiver features a compact design with all controls optimized for convenient use. You simply dig through simple menus to set the power level, adjust the keyer speed, or change filter settings. The radio has the 1602 liquid-crystal display, so all operating information is available at a glance. Free firmware upgrades are available via the internet.

Main Features and Specifications:

  • LCD-1602 Display
  • Built-in 12V Lithium Ion Battery
  • Built-in Microphone
  • Built-in Speaker
  • Built-in CW Decoder
  • IRF MOSFET Power Transistors
  • SO-239 Antenna Socket
  • 13.8V Power Supply Provides up to 10W PEP SSB Output (a bit lower at the higher frequencies)
  • Bands: 80, 60, 40, 30, 20, 17, 15, 12, and 10 m
  • Modes: USB, LSB, CW, Digital
  • DSP Filter: 4000, 2500, 1700, 500, 200, 100, 50 Hz
  • Functions: Automatic Gain Control (AGC), Noise Reduction (NR), Voice Trigger, Voice Trigger Xmit (VOX), RX Attenuator (ATT), TX Noise Gate, TX Driver Control, Volume Control, dBm/S-meter
  • SSB Reverse Sideband/Carrier Suppression Transmission: better than -45 dBc, IMD3 (two tones) -33 dBc, reception: better than -50 dBc
  • Open source firmware, built-in for Arduino IDE; allows experimentation, can add new functions, can share contributions through Github, software complexity: 2000 lines of code
  • Software-based VOX that can be used as fast Full Break-In (QSK and semi-QSK operation) or assist in RX/TX switching for operating digital modes (no CAT or PTT interface required), external PTT output/PA control with TX-delay
  • Fully digital and software-based SSB transmit-stage: samples microphone input and reconstruct a SSB signal by controlling the phase of the SI5351 PLL (through tiny frequency changes over 800 kbits/s I2C) and the amplitude of the PA (through PWM of the PA key-shaping circuit)
  • Three independent switchable analog front-end receiver attenuators (0 dB, -13 dB, -20 dB, -33 dB, -53 dB, -60 dB, -73 dB)
  • Receiver noise level MDS: -135 dBm (200 Hz BW) at 28 MHz
  • Receiver front-end selectivity: steep tuning frequency -45 dB / ten times roll-off +/- 2 kHz
  • Blocking dynamic range: 20 kHz offset 123 dB, 2 kHz offset 78 dB
  • CW decoder, straight/Iambic-A/B keyer
  • VFO A/B + RIT and Split, and switch the corresponding relay band filter through I2C
  • CAT support (Kenwood TS-480 subset), you can stream audio, press keys, and display text through CAT
Charge Charging Port for the Built-in Lithium Battery
Switch OFF to Shut Down

BAT: Built-in Battery Power Supply

13.8V: External Power Supply

DC 13.8V/3A External Power Supply Port
KEY Automatic CW Key Connection (A, B, Single Key)
PA External Power Amplifier, PTT Signal
MIC External Microphone 
UART Serial Communication Port (CAT Control Commands Compatible with Kenwood TS-480)
SPK External Speaker (when connected mutes the internal speaker)



Additional information

Weight 0.5 kg


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