The statement CATV coaxial cables or cables with foil/drain shields do not
have good shielding, because of transfer impedance and high resistance, was
made a while ago here on this reflector. I think the statement was those
shields are not good at MF or HF.
This past weekend, I modified a test fixture to test sample cables for
common mode.
I compared two samples. One was an 8-foot long sample of two-year-old
CommScope F6 dual-shield, and the other was a heavy copper braid RG6/U solid
dielectric that was inside. The F6 was pulled out from a cut cable a week
ago, one bonded foil overlaid with aluminum braid.
The cables were within a dB or two of each other.
http://www.w8ji.com/coaxial_cable_leakage.htm
73 Tom
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|