This afternoon I managed to do a little more work on the WSPR transceiver for 10m, building the oscillator/x2 multiplier stage and the balanced mixer for the TX part using a couple of 1N4148 diodes and a T50-6 tuned circuit. Carrier suppression is around 30dB without much effort. Next stages will be to add a linear amplifier to bring the DSB output to around 1W (500mW pep SSB carrier). Although I could combine the same mixer on RX and TX, I may stick with the Polyakov RX mixer as this is working so well.
I should have added that with a linear PA, the WISPY transceiver should also be perfect for PSK31 as the 14.060MHz crystal (when doubled) will certainly pull to the PSK31 10m sub-band.