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On 4/5/2011 3:20 PM, Bruce Beford wrote:
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<pre wrap="">***** High Performance Software Defined Radio Discussion List *****
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<pre><font face="Courier New" size="2"><span style="font-size: 10pt;">> Actually, the diodes will dissipate exactly the same heat as resistor(s) <o:p></o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;">> dropping the same voltage at the same current, unless the diodes are <o:p></o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;">> LEDs and thus converting some of the energy into visible light :-)<o:p></o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;">> P=EI<o:p></o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;">> 73, Lyle KK7P<o:p></o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;">Lyle,<o:p></o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;">Thank you for stating clearly, what should have been obvious. B^)<o:p></o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><font face="Courier New" size="2"><span style="font-size: 10pt;">73, Bruce, N1RX<o:p></o:p></span></font></pre>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
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Actually, it's not quite that simple. Obviously the power
dissipation will be the same in all cases, but that does not mean
that the temperature rise will be the same.<br>
The thermal characteristics will be different, expressed as degC/W
depending on the ease of getting the heat into the air. A small
diode will likely get hotter than a big resistor, but diodes mounted
on a nice heatsink will outperform the big ceramic resistors. If the
goal is to reduce the temperature of the circuit then some care
needs to be taken to find an optimal solution.<br>
<br>
73 Alf NU8I<br>
Scottsdale AZ DM43an<br>
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