[hpsdr] Demeter PSU design

[Jeroen Bastemeijer]

Dear Phil,

Thank you for your comment. I think we all are very curious to see how 
Mercury behaves in general, and for (Tiny) Demeter, in combination with 
a switching power supply. Is the SMPSU you are using a PicoPSU? Or are 
you using another type of SMPSU?

You are right about the efficiency of a linear regulator. Worst case, 
the dissipation would be around 12 Watts. Another option would be to use 
a switch-mode preregulator to approx 6V and then use a linear regulator 
for a clean 5V. Dissipation of the lin. regulator will be around 
1.5Watts in that situation.

The switcher for -12V is always necessary (if we want to run from the 
13.8V station supply).

Do you have any means to test the sensitivity of the HPSDR and/or 
Mercury for noise on the supply lines? Especially for "high frequency" 
noise (at the switching frequency (and harmonics) of a swicther) on the 
+5 Volt and the -12Volt rail?

73 Jeroen PE1RGE

Phil Harman schreef:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> Hi Jeroen,
>
> Good to see this discussion on Demeter. We are very close to seeing 
> how well the small switching power supply that plugs directly into the 
> ATX  connector on Atlas works with Mercury i.e. the picoPSU-120.
>
> I am using switching regulators on all my HPSDR supplies and have no 
> problem with noise etc.
>
> I suggest you review the use of a switching regulator to provide +5v 
> and -12v  from 13.8v after the results of the above test are completed.
>
> I am concerned that a linear regulator for the 5v supply will be very 
> inefficient.
>
> 73's Phil VK6APH
>
>
>
>
>
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-- 
Ing. Jeroen Bastemeijer

Delft University of Technology
Department of Electrical Engineering
Electronic Instrumentation Laboratory
Mekelweg 4, Room 13.090
2628 CD Delft
The Netherlands

Phone: +31.15.27.86542
Fax: +31.15.27.85755
E-mail: J.Bastemeijer at TUDelft.nl
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