I suggested that PVC gets warm in RF applications the other day and some present looked shocked. All that could ever be considered relevant to use of this material in an RF environment is well said here: http://www.g3ynh.info/zdocs/comps/part_6.html PVC is but one material this fine page addresses. Bookmark it, it is certainly worthwhile and comprehensive. This is just a section of Part 6, be sure to review all his pages.
Thanks for reading my Blog. Best, Chas W5PG