EXTRUSION OF CELLULAR POLYETHYLENE FOR CATV COAXIAL CABLES,
Abstract
The structural return loss requirements for CATV cable dictate that any periodic change in extruder delivery rate or screw speed cannot exceed a magnitude of 0.05-0.09 degrees depending upon cable size. This is beyond the capability of drive motor speed regulation systems normally employed. Use of synchronous motors with variable frequency speed control should eliminate this problem. If the screw speed pulse is not eliminated, SRL spikes can be forced out of the useable frequency range (above 300 MHz) by matching the extruder delivery rate to the cable size requirement in such a way that the line speed/screw speed ratio does not exceed 1.33. This means that the extruder should not deliver more than 1.6, 2.5 and 5.5 lb./hr./RPM, respectively, for the .360 in., .450 in. and .680 in. OD cables. It says that SRL problems would exist with one or more of the cable types made with any of the larger size extruders. Screw design is not critical as long as screw cooling is employed and the cooling conditions optimized. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 04, 1969
- Accession Number
- AD0698718
Entities
People
- B. H. Maddock