I do still have the ripple on the 65v supply. I rechecked for ripple on the other DC inputs to the protection board - all nice and flat. Out of curiosity, I removed the 20vac connection to the protection board to see what would happen - as this is essentially another input. The relay "on" time was reduced slightly when I did this, but the cycling continued. I was hoping that removing the AC supply would make the protection board think the receiver was turned off and disengage the relay.