An early review of the Airspy HF+ is available in the December issue of "Radio User" (UK).
Mike Richards got a preproduction unit and goes through the new design:
-coverage: LF to VHF (up to 260 MHz)
-using a new type of mixer (frequency changer) ahead of the ADC: 16 phase mixer, giving adequate rejection of harmonics up to the 21th harmonic, so there's no need to use a bank of many RF filters ahead of the mixer, also no need of high gain preamplifier
-using a low phase-noise oscillator
-using a Sigma-Delta 16 bit ADC, followed by a digital filter (design said to produce less quantization noise)
- from there, a decimation stage (as usual), then the output
From only a few days of use, Mike Richards noticed a "pretty amazing" strong signal performance on VHF (around 138 Mhz) and on HF (around 7 MHz).
The key components makers were not named. Maybe we are at the beginning of a new generation of (almost) low cost and high performance SDRs ?