Roger Lapthorn G3XBM has been designing a simpler and less expensive version of his 500kHz transverter for use with the FT817
The new version is still in the breadboarding stage but is fully functional on RX and TX (10W RF out at 13.8V). It will work on both 500kHz and 472kHz using CW, QRSS, DFCW, WSPR and OPERA.
On Saturday evening (July 21) Roger used it to exchange OPERA Op4 reports with PA0WMR (351km) despite his ERP being only 40mW.
Information and the schematic of the simple transverter is on his blog - http://g3xbm-qrp.blogspot.co.uk/2012/07/472500khz-transceive-transverter.html