Arecibo Observatory Ionospheric Heating Campaign

Reception on 5125 kHz using Icom IC-706 Mk II and Spectran at 04:23 UTC
 In the morning hours of July 31, 2017, I finally managed to receive the signals from Arecibo Observatory in Puerto Rico on 5125 kHz. The signal at my location peaked at S5-S6 using a vertical HF antenna, not tuned to the frequency.

Reception on 5125 kHz using Perseus SDR at 05:28 UTC

These signals, transmitted during the past week on 8175 and 5125 kHz, were a HAARP-line experiment, using the huge Arecibo spherical reflector. The TX power was 600 kW and the estimated ERP was 100-200 MW ! The current setup is described in a paper titled "The New Arecibo HF Facility Dual Array Cassegrain Antenna" by J. K. Breakall of Penn State University (available on-line).

Waterfall of Perseus SDR at 05:28 UTC

In parallel to direct off-air reception, I cross-checked with the WebSDR receiver at the University of Twente, to ensure that I did not receive a spurious signal.  On July 25, 2017, starting at 16:15 UTC I received an unidentified steady carrier on 8175 kHz, which was not reported by anyone else and I could not hear on the WebSDR site.

Possibly Arecibo transmission on 8175 kHz, on July 25, 2017, 16:39 UTC

The experiment was advertized in many on-line resources, like the ARRL web site, the Ham Radio Science Citizen Investigation (HamSCI) site, the UDXF mailing list and numerous twitter posts. Accordig to other listeners, at the end of the experiment Arecibo transmitted a SSTV signal in AM mode; unfortunately I could not remain in the shack this late. Other stations in Europe, however, reported good reception of the SSTV signal.

According to ARRL, reception reports shall be confirmed with QSL cards direct via W3HNK.