Dave,
I cut a high loss barrel apart. The construction does not look terrible for the frequency range involved. (It has a bulge in the center of the inner contact to help lock it in place in the insulator, but it is under 1 mm long.) The dielectric does not feel like PTFE or PE. It burns fairly easily with a possibly chlorine like smell, so I suspect it may be PVC, which would explain the high loss.
--John Gord
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On Tue, Oct 8, 2019 at 08:51 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:
It would be interesting to know why they are so bad. I wonder if the
dielectric is paper that¡¯s painted white to look like PTFE!
