This evening I extended my TX electrode spacings by connecting one end to the copper pipes in the house, almost doubling the effective TX baseline to about 20m. With this, my "earth mode" signals were much stronger and I was able to cover further than before in a "by ear" walk-about test around the fields locally. Ultimate range tonight was 0.4kms using 4W (probably less as the TDA2003 was hot and probably turning down the power) and receiving on an 80cm 30t loop, active HPF, small AF amp and crystal earpiece. Range was limited by 50Hz mains hum and background sferic noise. I must retry this set-up with my HF up-converter and FT817 this week, which has good rejection of 50Hz (and its harmonics) as well as a narrow CW filter.