Topband: Chokes for Beverages

[Mike Waters]

Does there always need to be electrical continuity between the various
shields along the length of coax? I don't think so.

According to
https://awapps.commscope.com/catalog/broadband/product_details.aspx?id=46911,
both the inner and outer foil in the stuff we use are
Aluminum/Polymer/Aluminum. That sounds like there's an insulating layer of
polymer, doesn't it?

Regardless, there is coax available that definitely has the shields
insulated from each other. The shields are connected together at the ends,
inside the connectors (not to mention there's capacitance between the
shields). What determines the characteristic Z of this coax is the ID of
the bonded inner foil and the OD of the center conductor, not the extra
layers of shielding.

73, Mike
www.w0btu.com

On Fri, Jun 22, 2012 at 10:19 AM, Bill Wichers <billw at waveform.net> wrote:

> > I'm thinking that the aluminum foil shields are plastic coated. If that's
> > the case, then only the inner braid would oxidize.
>
> The inner foil usually has a plastic backing on the "inside" (the side
> away from the braid). In the case of quad or tri-shield cable the outer
> foil does not normally have a plastic coating. Remember that the outer foil
> is between the braids in the case of quad-shield cable so there needs to be
> electrical continuity between the various shields. Plastic layers would
> prevent this.
>