K4POZ GI-7B Cooler Flaw
May 25, 2006
These are pictures of a GI-7B cooler which came from a tube that had failed. Close examination of the cooler revealed that the cooler was flawed in manufacture. The cooler had very large areas of porosity right next to the anode interface. The surface showed a roughness on first examination. Unfortuantely we didn't take a picture of the cooler before touching in with the lathe cutter.
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In this first view of the cooler, we have sanded the surface and lightly touched the center with a cutter on the lathe. You can clearly see all the air bubbles that had formed while it was being manufactured.
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This is another picture of the cooler from a slightly different angle.
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This is the cooler after we have taken a good bit of metal out of the center. The step in the turning near the outside left good metal yet removed enough that the cooler would still fit on the tube and clear the ceramic shoulder. W4ZT