Hi ady624,
Thank you for your reply - I returned the Rainbird and got an Orbit 3/4" jar top valve (57460) instead and everything works as expected now.
The first time I ran a bit of water through it after installation, it seemed to charge up the valve and close itself down within a couple of seconds.
The orbit valve is now closed even when the output side is not connected to anything and with no power. Its letting zero water through.
I think the RainBird valve may have been defective or at least incompatible - didnt determine which.
Appreciate the reply
Matt in Seattle