TRABEM wrote in message ...
[...]
Thanks,

T

Heresy maybe but I'd be inclined to just dump the transformer and bandpass
coils and caps and 10ohms etc. Use opamps for a low pass and a high pass
filter. Then add another inverting opamp to provide the antiphase for the
mixer chip. High 'Atmospherics' at these low frequencies mean pretty much
any opamp will be OK.
Use a resistor to present any input Z to the Ant'.
The FST3126 (or 74HC4066) works well with opamp drive.
regards
john