Very nice compilation!
So what is up with the PVC insulation? I know that PVC is particularly bad in terms of dissipation factor - but is it insulation self heating or just getting melted by a hot ferrite core?
I ask because I made a few measurements with a thermal probe on the side of a single core FT-240-31 with 8T RG-11 that is a choke I have for my 10m antenna. What I discovered is the the temperature rises very quickly on the core surface when you turn on the power and then more slowly diffuses into the center of the core. Similarly, when the power is shut off, the temperature falls relatively quickly on the surface, as the surface heat conducts inward or is lost to convection with the air. I can imagine that extreme non-uniform heating could lead to fracturing of the brittle core material.
Any comments?
Gary AF7NX
