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

[Graham / KE9H]

Dominic:

Nothing actually uses the -12V supply, so most people leave it turned off,
anyway.  Did you install the jumper that turns it on?  Default is off.

--- Graham

==



Dominic Hawken wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> 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.
>
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