Hi Bruce. 8270.03 Hz is probably the best known beacon but others like from Canada (Joe VO1NA) I think had/has a beacon on 8270.000277 Hz that may be active. Anyway, you can get info about ELF transmission on the VLF group on groups.IO. Below is a copy of a message I earmarked and may help you get more info. 73 Gedas W8BYA"I'm glad that my transmission of a carrier helped you test your receiving system.
Unfortunately, there are very few amateur radio operators still transmitting on VLF frequencies.
My receiving system looks similar, except my loops are triangular with 4-meter sides.
This has the advantage that only one support point in the middle is needed (mast or tree).
My system is described on page 6 of the following link:
https://dl3jmm.darc.de/Funkbetrieb_auf_Frequenzen_kleiner_8300_Hz_V1.3_en_DeepL.pdf
https://dl3jmm.darc.de/
Unfortunately, my receiving location is also surrounded by sources of interference: a 110 kV high-voltage power line at 250 meters,
a large hospital at 500 meters, and several photovoltaic systems.
...
To form a cardioid pattern using two magnetic loops and an E-field antenna, I first adjusted the amplitudes of the three antennas to the same value in the Raspberry Pi/Octosoundkate using the "alsamixer" program.
Then, using a strong transmitter, I searched for the minimum in the radiation pattern (with vtmix).
As a final step, I optimized the minimum by adjusting the phase of the E-field antenna in vtmix.
echo "Azimuth = 270°"
vtmix -c-1.0,0.0,1/45 @raw:3,4,5 @richt
I wish you much success with further optimizing the system and hope you can receive as many transmissions as possible from amateur radio operators, perhaps later also with EbNaut.
My transmissions are clearly visible on some grabbers; Paul used to be able to receive me regularly on 5.17 Hz in Todmorden.
http://web1.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
https://iw4dxw-bplaced-net.translate.goog/JN65cq.htm?_x_tr_sch=http&_x_tr_sl=en&_x_tr_tl=de&_x_tr_hl=de&_x_tr_pto=sc
https://iw4dxw-bplaced-net.translate.goog/?_x_tr_sch=http&_x_tr_sl=en&_x_tr_tl=de&_x_tr_hl=de&_x_tr_pto=sc
Best regards,
Bernd
DL3JMM"