Evaluating Online SDRs For MW Capabilities

courtesy: https://sdr.hu/

In a previous blog I described the amazing KiwiSDR network of online receivers. A quick check of the network as I write today's blog shows that there are presently 207 active online receivers distributed throughout the world!

Over the past year, there has been a growing interest in using many of the online receivers during the monthly CLE NDB listening events, all focused on the medium frequency (MF) part off the spectrum just below the AM broadcast band. Some use the SDRs to search for unlogged beacons while others use them because their home locations have become too noisy to hear anything using their own radios, a growing problem for listeners everywhere.

One ardent NDB DXer, Dan Petersen, W7OIL, (located in Vancouver, WA) has become a regular Kiwi network user as well as a regular contributor to the very valuable RNA / REU / RWW list of worldwide beacon activity. Over the past year, Dan has been keeping careful notes on not only what he has been hearing but also on how well many of the online radios perform on the MF NDB band.

As it turns out, many receivers perform very well on the HF bands but are dreadfully inadequate when it comes to the medium wave frequencies. Many are plagued with high noise levels, switching power supply signals, intermod or inadequate antenna systems, making them unusable for weak signal DX work below the broadcast band.

Other receivers however, are superb performers, as evidenced by their quiet low noise locations and well engineered antennas, providing the ideal opportunity to conduct some serious medium wave weak signal detection.

Dan has now produced the start of an ongoing guide, mainly focusing on the various Kiwi Network receivers that he has tested, rating them with regard to sensitivity and local noise, when used in the 200 - 500 kHz range only.

His SDR EVALUATION LIST (in .pdf form) can be downloaded from here, and will be updated periodically, as other online receivers are evaluated.

If you are plagued with local noise on the MF band yet would like to do some weak signal DXing, especially during the monthly NDB CLE activities, the online SDRs may be of interest to you. With Dan's helpful groundwork already giving you a leg up, hopefully you can give them a try sometime soon!


Speaking of monthly CLEs ... the recently completed weekend event (CLE232), was a rough one, with worldwide lightning noise as well as an active geomagnetic field hampering reception for all participants. In North America, all three nights were terribly noisy and propagation was poor.

As is so often the case, Friday night was the 'best' of the three nights but only 18 stations were heard here. My log is shown below.

It was nice to hear POA in Pahoa, Hawaii, still going strong as it is located close to the present volcanic eruptions.

All signals were heard on a Perseus SDR feeding an inverted-L antenna, resonated to 300kHz.

26 09:00 325.0 YJQ Bella Bella (Campbell Island), BC, CAN
26 09:00 326.0 YQK Kenora, ON, CAN
26 10:00 326.0 DC Princeton Municipal Apt, BC, CAN
26 06:00 328.0 YTL Big Trout Lake, ON, CAN
26 09:00 328.0 LAC 'Lacomas' Fort Lewis, WA, USA
26 09:00 328.0 5J Coronation, AB, CAN
26 06:00 329.0 YHN Hornepayne, ON, CAN
26 09:00 329.0 YEK Arviat, NU, CAN
26 09:00 329.0 X2 Athabasca, AB, CAN
26 10:00 329.0 PMV Plattsmouth, NE, USA
26 09:00 329.0 PJ Robinson (Whitehorse), YT, CAN
26 09:00 330.0 0O UNID, XUU
26 09:00 332.0 XT Terrace, BC, CAN
26 09:00 332.0 WC White Rock (Abbotsford), BC, CAN
26 10:00 332.0 VVV Ortonville Municipal Apt, MN, USA
27 09:00 332.0 VT Buffalo Narrows, SK, CAN
26 12:00 332.0 POA Pahoa - Hawaii Island, HWA
26 06:00 334.0 YER Fort Severn, ON, CAN
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

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