> 15:15 UTC on 136.175 kHz, i bet this was your signal! ;-)

Could be?  Carrier on air 136.175 kHz intermittent since 16:40,
continuous since 16:54 and later will move to a frequency in
the OPDS band for some EbNaut.

236W DC input.

Instant LF coupling transformer: rummage in the shed until
you find a 50 metre coil of 3-core heavy duty mains cable.

Diameter about 40cm, turns 40.

Each wire measures 630uH with the other wires open circuit.
With one wire shorted, the other wires measure 45uH each.

I think that's not bad and the leakage inductance is half of
what I need to tune the antenna anyway.   I just needed a small
extra coil to bring it into tune.  Found a small coil of heavy
loudspeaker cable - about the right inductance, wired it in
series and bingo!  Tunes 136 very nicely.   So, I didn't actually
have to wind anything in the end.

Near the end of the coax a stream emerges from the ground in
a muddy patch.    I pushed some scrap copper pipes into the mud.
Three good stakes a few metres apart.  Instant ground terminal.

I'm getting to like LF - you can take some liberties.  Coils of
mains cable as transformers, terminal blocks as RF connectors,
buckets of salty water for dummy loads.

--
Paul Nicholson
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