Russian RSDN signals on my AFEDRI SDR-Net

Months ago I decided to replace the Mini-Circuits transformer (a type T4-1), in the input stage of my AFEDRI SDR-Net, with a pin-to-pin compatible type T4-6T, because of the bandwitdh of the latter being more suitable for reception of VLF.
Last night, at the end of a listening session dedicated to NDB chasing (and in particular to the evaluation of the LZ1AQ loop amplifier that I received recently from Roelof Bakker, PA0RDT), I thought I'd take a quick look at how my little reception system was behaving at VLF.
I was pleasantly surprised to see that it was possible to receive - at about 20 dB over the noise level - signals from the russian RSDN-20 navigation system (also known as the Alpha navigation system), on the three main frequencies of 11.904761 kHz, 12.648809 kHz and 14.880952 kHz.
The image below was captured while looking at the waterfall on HDSDR.

For the coming Christmas Eve, I was planning to listen to the traditional SAQ transmission from Grimeton on 17.200 kHz using a dedicated VLF antenna system. Now I think that I will try to do the same by using the same reception system that I'm using normally for LF and MW. A nice improvement.