[hpsdr] How do you switch power to Atlas

[Mark Leone]

On 12/3/11 6:09 PM, Chris Smith wrote:
> Mark
>
> I'm pretty certain that pulling pin 4 low on a standard ATX PSU has the effect of powering up the PSU. If you're using the LPU then pin 4 will have no effect, so a jumper from T7 to T8 won't have any effect either.
Thanks Chris. I think you're referring to pin 14 on the ATX connector, 
and you're right that it has no effect on LPU. After posting, I noticed 
a comment on the LPU Wiki page that it ignores the ATX power-on signal 
and is always on. I was referring to pin 4 of the voltage regulators, 
not the ATX connector. That's a voltage disable signal, which turns the 
output off if it goes below 0.8 volts. In the LPU design, the Vdis 
signal is tied to the Vin signal, which prevents it being used as a 
power on/off control, short of modifying the PCB, which I don't want to do.

On 12/3/11 6:21 PM, n3evl wrote:
> FWIW, I'm just today in the process of replacing the LPU with a 
> PicoPSU and discovered that while LPU does not care about T7 T8, the 
> PicoPSU certainly does.  Fortunately I already had a switch wired 
> across T7 T8 since, a while back, I'd used Atlas with a conventional 
> PC PSU. 

Thanks for that Pete. I'll look into switching to PicoPSU. It's my own 
fault for not reading the LPU Wiki page more carefully, but I need a PSU 
that works with a power switch. And it's not just because I already 
drilled a hole in Pandora. I have a 100 watt transceiver right next to 
my HPSDR, powered from the same power panel, with just a coax switch 
between the two transceivers and the antenna. So I really don't want to 
have either of them powered up when the other one is transmitting; and 
removing power pole connectors is not convenient.

Mark - K4XML


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