KLUBNL.PL articles:
A very simple receiver for 136kHz
Operating a longwire on VLF, 630m and 160m-17m via a simple matching circiut
Simple 1PPS signal source and distribution amplifier
Simple setup for monitoring of VLF signals using vlfrx-tools
Universal Antenna autotransformer for 8,27kHz, 136kHz and 472kHz