[hpsdr] Hot ADC

[Dale Boresz]

Just another set of data points ...

Using a small thermocouple, I measured 62 C on the top of the ADC, and 
66 C on the foil pad on the back of the board. Ambient temp in the area 
of the boards is about 26 C. Measurements made after approx. 30 minutes 
of operation.

Dale
WA8SRA


Philip Covington wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> On Tue, Jan 13, 2009 at 1:53 PM, Kjell Karlsen <la2ni at online.no> wrote:
>   
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> I do not have a thermometer to measure the temp of the ADC but it felt very
>> hot, much more than I liked. I glued a small Heatsink on top of the chip and
>> it helped a bit. When I had a look at the  aeria on the bottom of the board
>> directly under the chip, I discowered that the solder may not have melted
>> properly when the board was produced. There was no sign of solder up in the
>> holes below the ADC. I resoldered the aeria and now the bottom of the card
>> is warmer than before. Unfortunately I can not confirm this by measurements,
>> but my feeling is that the chip is colder now.
>>
>> Can someone do a tempereture measure before and after resoldering and report
>> back?
>>
>> Kjell
>>     
>
> I have measured the LTC2208 ADC temperature of quite a few QS1R
> receiver boards (this is done as part of the manufacturing tests).  If
> the ADC is soldered properly, the average temperature on the top
> surface of the ADC is around 54 C ( 130F ).  If it is considerably
> higher than that it is usually because of inadequate soldering of the
> thermal pad on the underside of the ADC.
>
> I don't know how the thermal pad is designed on the Mercury, but 70 C
> ( 158F) is excessive, I'd think.
>
> Gluing a heatsink to the top of the ADC does not help much.  The heat
> removal should be via the thermal pad through the PCB.
>
>   


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