<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii">
<TITLE>Message</TITLE>
<META content="MSHTML 6.00.6000.16481" name=GENERATOR></HEAD>
<BODY>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007>Hello Jeroen,
All,</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007>As to the question
of if there should be a number of smaller boards or one (or two) bigger boards,
</SPAN></FONT><FONT face=Arial size=2><SPAN class=453194115-29062007>I think it
would be the best option if we want optimal flexibility and
scalability.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007>On the other hand a
single board with all the different regulators and control processor on it
has the advantages of being compact and the easier interconnections between
them.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007>I don't know what
the aim is for the upper limit of the currents/voltages/power for the different
regulators planned for Demeter and the resulting total dissipation that goes
with these.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007>I could imagine that
you would like to dissipate the heat to the outside of the HPSDR
enclosure using external heatsinks (avoiding noisy
ventilators)</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007>All that said. a
number of questions/remarks that come to mind:</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007> - Will these
boards have external power devices that need to be mounted off-board (e.g. the
linear regulators)?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007> - Could one scale up for more current? (more
power devices etc.), What about r<SPAN
class=453194115-29062007>egulators in parallel for higher
current?</SPAN></SPAN></SPAN></FONT></DIV><FONT face=Arial><SPAN
class=453194115-29062007><SPAN class=453194115-29062007>
<DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007> - Could one add more voltages
(regulators)? </SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007> </SPAN></FONT><FONT face=Arial size=2><SPAN
class=453194115-29062007>- Would separate boards give more
options for EMI suppression (earthing, shielding, mechanical)
?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007> - Mechanical
mounting </SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007>
- Attached with their power devices directly to an (external)
heatsink? </SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007> Running<FONT face=Arial><SPAN
class=453194115-29062007><FONT size=2><SPAN class=453194115-29062007> longer
wires to an external power device on a heatsink is not a good
idea</SPAN>,<SPAN class=453194115-29062007> especially not for a
switcher... ;-)</SPAN></FONT></SPAN></FONT><FONT face=Arial><SPAN
class=453194115-29062007><SPAN
class=453194115-29062007></SPAN></SPAN></FONT></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007> -
Have a particular regulator as close as possible to the attached user (e.g. a
power amp)?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007> -
Scalability:</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007> -
With a linear regulator it is relatively easy to increase the output current;
you could have a low power board for a limited current and scale up by
adding </SPAN></FONT><FONT face=Arial size=2><SPAN
class=453194115-29062007>external power devices</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007> -
This is not the case with a switching regulator as far as I
know.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007> This would require
besides adding a more high power switcher device also at least exchanging
inductors and capacitors with higher power versions and other C and L
values?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=453194115-29062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007>I think some of these aspects are good reasons to have
regulator board(s) to be separate ones?</SPAN></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007></SPAN></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007>I am aware of the fact that this makes the internal
wiring more difficult though..</SPAN></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007></SPAN></SPAN></FONT><FONT face=Arial size=2><SPAN
class=453194115-29062007><SPAN
class=453194115-29062007></SPAN></SPAN></FONT> </DIV></SPAN></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007>The PSU controller board containing the
microcontroller I think should be a separate board
anyway.</SPAN></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007>That could even be on ATLAS for easy connection to
backplane signals for e.g. voltage monitoring, Power Good signal
etc.?</SPAN></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007></SPAN></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007>So I think the answer for me in general would
be "YES!!"</SPAN></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007></SPAN></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007></SPAN></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007>73's,</SPAN></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007></SPAN></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=453194115-29062007><SPAN
class=453194115-29062007>Henry.</SPAN></SPAN></FONT></DIV></BODY></HTML>