RS-HFIQ 5 Watt HF SDR Transceiver by HobbyPCB

Here we take a look at the RS-HFIQ 5 Watt HF SDR Transceiver by HobbyPCB.

The RS-HFIQ is an open-source HF transceiver project designed to translate I and Q baseband signals to RF in the 80/60/40/30/20/17/15/12/10M Amateur Radio bands. The I and Q signals must be provided/processed by external signal processing which could be a PC running Software Defined Radio software or a stand-alone digital signal processor

The receiver in the RS-HFIQ consists of 5 band-pass filters to reject out-of-band signals, an LNA with frequency dependent gain and a conventional quadrature down-converter.

The transmitter in the RS-HFIQ uses a Quatrature up-converter followed by the same band-pass filters used by the receivers, a 5W power chain and a low-pass filter bank.

The Local Oscillator is based on a Silicon Labs SI5351 chip that can product up to 3 RF outputs, the LO signal for the up/down-converter, a built-in test signal for calibrating I and Q offsets and an external signal.

The control of the SI5351 and all switching functions is provided by an Arduino Nano running open-source software and programmed with the Arduino IDE.

Special care has been taken to insure noise and ground-loop set-up. The RS-HFIQ has three separate DC isolated ground planes; RF/Chassis ground, Baseband/Audio ground and Digital ground. This allows the same PC to be connected to the audio in/out and the USB port on the Arduino Nano without creating noise/grounding issues. 

5W not enough power?  Add a HARDROCK-50 to your station to boost up to 50W.  The RS-HFIQ and HARDROCK-50 seamlessly integrate together for a powerful base station!


  • Frequency Range – 3-30MHz (performance guaranteed on 80/60/40/30/20/17/15/12/10M ham bands)
  • Sensitivity – MDS < -128 dBm on 80M dropping to < -135 on 10M (depending on processing bandwidth and sound card performance)
  • Noise Figure –
  • TX Power 5W typical, 4W minimum
  • LO Feed-thru < -50 dBc @ 5W output
  • Spurious and Harmonics < -50 dBc typical
  • DC Power 13.8VDC, 2 amp max plus USB power for the Arduino Nano
  • Size – 100MM x 160MM


The RS-HFIQ is NOT a stand-alone transceiver, it is a part of a Software Defined Radio system. The SDR system consists of:

  • Radio front-end – The RS-HFIQ
  • Data conversion – Analog to Digital and Digital to Analog typically provided by a high-quality sound card
  • Computer hardware – A digital signal processor or high speed general purpose processor.
  • SDR Software – to process TX and RX signals

While many different configurations are possible and even encouraged, we have developed a ‘standard’ configuration that will help users new to SDR’s go up and running quickly. To get on the air with the RS-HFIQ in the standard configuration  you will need:

  • StarTech – 96 KSPS sound card 
  • Windows PC – running Windows 7, 8 or 10 with speakers and two available USB ports
  • 13.8V 3A power supply
  • Microphone
  • Various USB and audio cables
  • HDSDR and Omni-Rig software 
  • A valid Amateur Radio license is required for transmitting
  • Antenna system

Visit the RS-HFIQ Transceiver Wiki for more information.





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