[hpsdr] LPU & Multiple boards on Atlas

[K1rqg at aol.com]

Please beware if you are using an LPU to power your HPSDR system.
 
As noted in LPU documents, it is rated 12 V @ 2 A and 5 V @ 2 A.
 
The following info is contained in the same document:
 
               12 V         5 v
OZY       .001  A        .1 A
PENY      .4 A           .2 A
MERC     .2  A           .5 A
 
and on Jan 12, Phil posted the following:
***** High Performance Software Defined Radio Discussion List  *****

Please note that with Metis running at 1Gb/s the +5v supply current  will
increase by approximately 0.75A.

For this reason (for folks that  are using LPUs), and the fact that we
don't need 1Gig rates to the PC just  yet, the initial release of Metis
code will run at 100Mb/s.

73  Phil...VK6APH

*******
 
End result is that the LPU is NOT suited to run HPSDR with multiple Mercury 
boards, Metis, Excalibur ( not sure on power usage), and Peny. The 5 V  
regulator 
is only rated at 2 A and I have experienced the 2.2 ohm resistor burning  
up. 
I measured the 5 V current drain with 5 boards on Atlas and in receive  mode
it was 2.97 Amps. This exceeds LPU specs. Add the fact that at 1Gb/s  the
current will increase by .75 Amps.
 
If you are experiencing less than proper operation of your system, check  
your
voltage at the Atlas test points.
 
PLEASE BE AWARE!
 
73 de Joe
K1RQG
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