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what is the white powder inside Chassis Mount Resistor tjt300 6r8

manojroy123

what is the white powder inside Chassis Mount Resistor tjt300 6r8 provided by TE

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    It could well be a harmless calcium or aluminium oxide or similar, it conducts heat from the resistive element inside the packaging to the outer 'shell' (which is usually aluminium with fins) a lot quicker than air. Such resistors are usually quite heavy (for a resistor) and have mounting holes at each end for bolting them to a chassis which improves the heat dissipation. I expect they are still in use, so please please check the spec before use. I say this with emphasis because there are transistors about with white powder inside, usually encased in what looked like ferrite. We used them for PA stages in RF transmitters, but in this case the white powder can be beryllium oxide which is highly toxic. As a student (long long ago) I asked an older member of the department what the symptoms of berylllium poisoning were. His answer was "You die..."  He may have been exaggerating slightly, but why take the chance?

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    It could well be a harmless calcium or aluminium oxide or similar, it conducts heat from the resistive element inside the packaging to the outer 'shell' (which is usually aluminium with fins) a lot quicker than air. Such resistors are usually quite heavy (for a resistor) and have mounting holes at each end for bolting them to a chassis which improves the heat dissipation. I expect they are still in use, so please please check the spec before use. I say this with emphasis because there are transistors about with white powder inside, usually encased in what looked like ferrite. We used them for PA stages in RF transmitters, but in this case the white powder can be beryllium oxide which is highly toxic. As a student (long long ago) I asked an older member of the department what the symptoms of berylllium poisoning were. His answer was "You die..."  He may have been exaggerating slightly, but why take the chance?

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