Hi All,
In an earlier message, I listed the cooling modifications I deployed to reduce DE case heat.? It worked but I did not like the haphazard solution I whipped up.? As this thread matured and the ability of the heat sink to reject heat was studied, it became clear to me that the heat sink alone was unable to keep the finals safely in the operational range of the devices at higher operational levels.? So I added fans to my DE machine which makes the radio less portable but more reliable.
Below are a few pictures.? In essence, I added three (3) 70mm brushless fans, added a few cooling penatrations under the PCB (and under the finals) and blocked the existing vents on the right side.? The idea is to move the highest volume of air from left to right within the enclosue and force air over the existing heat sink.? I've not taken many heat measurements but with hand held thermometer and without fan assist, the heat build up measured at the heat sink, between the transistors kept rising but leveled off within several seconds with a single fan pointed at the heat sink during WSPR operation at 10 watts.? With two fans virtualy covering the entire heat sink, I am sure the performance of the heat rejection will improve.? I may add improved insulators later but for now I am using generic silicon.
Parts:
Fans? ?
LM317 Module? ?
Aluminum Nitrate Insulators? ?TBD
I know this wasn't terribly scientific but I have noticed that the case never gets warm and the wattage produced remains constant over hours of WSPR production.? That's a fairly significant improvement, for my machine.? I'll provide temperatures later (once I get some hardware).
Cheers, Scott?
