[hpsdr] Anyone help with a-12v problem with LPU?

[Dominic Hawken]

I've clearly made a mistake building my LPU, but I can't spot where. 
I've checked all the obvious things - polarity etc.

It's with the -12v supply from U4 - the others are fine.

When I plug the LPU into my bench supply and slowly turn up the voltage 
from 0v, I see -5v on the -12v output when the input voltage of the LPU 
is less than around 7v.

Above 7v into the LPU, the -5v I see above starts to fall back, until it 
drops to completely nothing at an input of 10v plus.

Any help as to the likely source of the problem would be much 
appreciated - it's so frustrating not being able to put it into use yet!

Thanks all,

Dominic G6NQO.