@Mike5000 here the answer from LZ5HP
The size of heatsink depends on how intensively PA is used. You can check first, temperature up to 70deg C is not a problem.
There is no RF VOX in PA. You need to connect power supply 28V permanently . Only 1 additonal connection is needed - between sequencer output of TRV (second ring of 3.5mm jack) and PTT pin of PA. The jumper in PA must be set to position 1.
Depending of connecting cable loss , you need to reduce transverter power by TX trimmer. PA input drive can be monitored at "DRV" pin, voltage must be about 0.2V .
PA output power can be monitored at "FWD" pad , voltage must be about 3.5V for full power.
Last tests shows, that 20W is too high power, if you use 70cm dish or larger. You can reduce PA power by reducing drive or by reducing power supply voltage down to 12V, @12V output power is ~4W.