[hpsdr] Noob LPU question

[Dan Babcock]

Hi Larry,

It has been a while since I built my LPU but I remember  the assembly procedure 
for the regulators and heatsinks well.  You are  correct the heatsinks are 
soldered to the PCB.  The assembly sequence is  to 1) Apply a small amount of 
thermal compound, (CPU heatsink compound  or 20% zinc oxide compound from the 
pharmacy) to the back of each of the  regulators 2) Attach the regulators to the 
heatsinks with the provided  hardware.  In order to make the alignment and 
soldering of the regulator  pins easier, do not tighten the hardware. 3) Align 
the regulator pins  and the heatsink pins with the holes in the PCB. 4)  Solder 
the  heatsinks to the PCB. Hint: If you don't have an assistant to hold the  
parts in place, wind three or four turns of solder wire around a pair of  needle 
nose  pliers with a diameter large enough to fit over the heatsink pin.  5)  
Solder the regulator pins to the PCB. 6) Tighten the hardware.

The  only caveat is to make sure you put each regulator / heatsink in the  
correct position on the board.  It is easy to mess this up and almost  
impossible to fix.

One other suggestion based on my experience.   There is some freedom of movement 
with the positioning of the ATX  connector.  Make sure that you don't 
inadvertently cover the through hole on the  PCB for one of the leads of the 
large ceramic resistor with the edge of  that connector.  


73,

Dan N4XWE




________________________________
From: Larry Gadallah <lgadallah at gmail.com>
To: hpsdr at openhpsdr.org
Sent: Sat, December 4, 2010 5:39:55 PM
Subject: [hpsdr] Noob LPU question

***** High Performance Software Defined Radio Discussion List *****

Hi all:

I'm in the midst of building my first LPU, and the instructions direct me to 
bolt the regulators to the heat sinks and then to bolt the heat sinks to the PCB 
using the supplied nuts and the studs on the bottom of the heat sinks. Only 
thing is: There are no supplied nuts, and the studs on the heat sinks are not 
threaded. In fact, they look like they are tinned and hence indented to be 
_soldered_ on to the PCB. Is this the case, or do I have some defective parts?

Thanks es 73,
-- 
Larry Gadallah, VE6VQ/W7                          lgadallah AT gmail DOT com
PGP Sig: 917E DDB7 C911 9EC1 0CD9  C06B 06C4 835F 0BB8 7336



      
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