WISPY is a full 2-way WSPR transceiver but there may be occasions when just a simple WSPR TX is needed. This is the (current) schematic of the WSPR TX beacon for 10m, but the very same schematic with a different crystal and values should work on any HF band. On lower bands the doubler could be removed and a simple on-frequency crystal substituted. The doubler approach was the cheapest way for 10m WSPR.
The schematic needs rationalising and some further simplification, so treat this (as always) as a design starting point.