QSL: 4KZ Innisfail, QLD 5055

The 4KZ 1620 kHz 400-watt relay is quite easy to hear at my location, despite the 12,800 km distance.

Not so with their 1.3 kW station on 5055 kHz! After a few futile (albeit random) attempts, I decided in February to monitor and record three top of the hours every day. I also wanted to do an A-B comparison between the Airspy HF+ and the SDRPlay RSP1A. So both were connected to the same antenna, two different PCs with HDSDR running on both. After quite a number of days, the signal was finally readable.

The HF+ is known to be a very sensitive SDR, while the RSP1A is more average when microvolts are measured. So, there "should" be a difference in audio recovery, at least on threshold signals. There was. When signals are very weak and the noise floor is low, better sensitivity is indeed audible. Here is how 4KZ was heard at the time. Headphones recommended.

The 4KZ General Manger Al Kirton is a DX-friendy guy, and sent off a proper QSL card with a sticker and info in the mail.

Airspy HF+ Discovery: Sensitivity Measurements

Time to find out how sensitive the HF+ Discovery is! Since it is basically the same receiver as the HF+, with preselectors, I expected sensitivity on MW to be roughly the same. Which turned out to be true.
On 500 kHz, I measured -110 dBm, on 1000 kHz -111, and on 1500 kHz -110 dBm. Using SDR#, v.1708, 6 kHz bandwidth with AM mode, and a 30 % modulated, 400 Hz signal from the signal generator.

The "Receiver Sensitivity Measurements" table has been updated accordingly. Excellent numbers.

Airspy HF+ Discovery Has Landed

Well admittedly, the Norway transport was on road, taking twice as long as from Shanghai to Oslo. But it arrived! Just fired it up at my home in Tana, no antennas available, so only to get a feel of it (feels warm to touch) and do the latest firmware update. Sensitivity measurements will be done on Friday.

My kitchen weight says 32 grams. By a good margin the lightest SDR I've had so far.