John, a simple "Softrock style" front end adapted for 136 or 500kHz should work very well if you have a decent soundcard. There are a few SDR programs that works with such a front end, for example I2
My receiver for this band is a Lowe HF250 with a 2m x 2m loop (estimated effective height 8 m). It received G3XIZ surprisingly well on Sunday even though the selectivity of the receiver leaves someth