Name: SDRplay RSPduo
Brand: SDRplay

2018

Introduced

Frequency	1 kHz - 2 GHz continuous (NO GAPS), dual tuner
Bands	VLF, LF, MF, HF, VHF, UHF, L-band
Power	RECEIVE ONLY. Dual independent tuner SDR receiver.
Modes	All modes via SDRuno/SDRconnect
Weight	150 g (5.3 oz) - ~150g estimated. Steel enclosure (same form as RSP2pro).
Connector	SMA-F (2× SMA + 1× Hi-Z for HF wire antennas)
Year	2018

Connectors

antenna sma1	SMA-F (tuner A, 1 kHz to 2 GHz)
antenna sma2	SMA-F (tuner B, 1 kHz to 2 GHz)
antenna hiz	Hi-Z input (0-30 MHz wire antenna with notch+LPF)
clock in	clock input (GPS reference)
clock out	clock output (multi-unit sync)
usb	USB 2.0 Type-B
power req	USB bus powered.

a dual-tuner SDR, two independent phase-coherent receivers in one box dual independent 14-bit tuners through single USB 2.0 interface single tuner mode: 10 MHz bandwidth anywhere 1 kHz - 2 GHz dual tuner mode: two simultaneous 2 MHz windows anywhere 1 kHz - 2 GHz phase-coherent dual tuners enable: direction finding, spatial diversity, polarization diversity, noise reduction cross-band full-duplex reception (e.g. HF + VHF, VHF + UHF simultaneously) simultaneous Dump1090 ADS-B + VHF ATC voice reception 3 software-selectable antenna inputs: 2× SMA + 1× Hi-Z (for HF wire antennas 0-30 MHz) Hi-Z input with notch filter + 0-2 MHz low-pass filter for LF/MW 11 band preselect filters software-selectable LNA + 4.7V bias-tee 0.5 PPM TCXO + external clock input/output (GPS reference, multi-unit sync) SDRuno + SDRconnect FREE (Windows/macOS/Linux/Raspberry Pi) calibrated S-meter/RF power/SNR measurement with datalogging to CSV steel enclosure RECEIVE ONLY

Strengths

A sub-$300 SDR with dual independent tuners. Phase-coherent operation enables direction finding and diversity reception, with cross-band simultaneous monitoring (HF+VHF, ADS-B+ATC). It has a Hi-Z input for HF wire antennas, 11 preselect filters, clock in/out for GPS sync, and a calibrated S-meter with CSV logging.

Weaknesses

Receive only. $260-300 (about 2x the RSP1B). Dual mode is limited to 2 MHz per tuner (10 MHz only in single mode). USB 2.0 (not 3.0). The diversity software is still evolving. Some third-party software is limited to a single tuner.

Verdict

Two receivers in one box. The RSPduo is a sub-$300 SDR with dual independent phase-coherent tuners. Monitor HF and VHF at once, do direction finding with two antennas, or reduce noise with spatial diversity. The Hi-Z input for HF wire antennas and clock I/O for a GPS reference make it a serious tool. If you need two receivers without buying two SDRs, little else competes at the price.

The SDRplay RSPduo is the standout in SDRplay's receive-only lineup because of one feature: it has two completely independent tuners in a single box. Each covers the same vast 1 kHz to 2 GHz range, and the two can run at the same time, letting you monitor, say, an HF net and a VHF repeater simultaneously, or feed both into diversity and direction-finding applications. It is a receiver only and does not transmit.

Both tuners use 14-bit conversion. In single-tuner mode you get up to 10 MHz of bandwidth; when running both tuners at once, each stream is capped at 2 MHz (about 1.5 MHz alias-free). The board carries three antenna ports (including a high-impedance input handy for longwire antennas on the low bands) plus external clock input and output for synchronization. The trade-off is that the dual-tuner mode is best supported in SDRplay's own software; not every third-party application handles both tuners cleanly.

Launched in 2018, it remains current. It sits above the single-tuner RSP1B in capability, and alongside the RSPdx-R2, which trades the second tuner for enhanced performance on the low bands.