Testing the Airspy HF+ Against the FDM-S2 on the Medium and Long Wave Bands
Over on the swling.com blog (short wave listening) contributor Guy Atkins has posted about his comparisons of the Airspy HF+ and the Elad FDM-S2 SDRs on the Medium Wave band. In the test he connected the two SDRs to the same ALA1530S+ Welbrook loop antenna via a splitter and recorded some audio comparisons.
It appears that the Airspy HF+ even outperforms the FDM-S2 on one particular test where he tries to listen to 1540 kHz which is just 10 kHz away from a strong signal at 1550 kHz. He also writes:
It became apparent quickly that the upstart HF+ provides strong competition to the Elad SDR. Clearly, the AirSpy’s trade-off is bandwidth for raw performance at lower cost–approx. 660 kHz alias-free coverage versus about 6 MHz maximum for the Elad.
Also in a later post on the swling.com blog Guy makes an addendum where he swaps out his ALA1530S+ Wellbrook loop antenna for the ALA1530LN Pro which overloads his receivers less. He notes that with the new antenna 6 dB of attenuation is required for the FSM-S2 in order to prevent overloading. With the HF+ very little overloading apart from a weak image could be found, and that was removed by adding 3 dB of attenuation.
He also tests longwave reception with the two receivers, and this time finds that the HF+ seems to have additional MW spurs in the LW band, compared with the FDM-S2.