> I noticed something recently about at least one of my spools of flooded > quad-aluminum-shield "RG-6". Since the flooding compound is only in the > outer shield (the braid right under the outer jacket), it seems possible > that under certain circumstances, water could still wick its way along the > inner shield and cause degradation of the inner braid and the foil > surrounding the dielectric.
The flooding compound is intended to protect the cable against *minor* defects in the jacket such as *small* punctures or nicks. The general idea is to protect against the kinds of very minor damage a cable would get during installation or over time (such as rocks abrading the jacket underground or tree branches abrading an aerial cable in the wind). Large areas of damage will still harm the cable. If a big critter gets a taste for coax some night you're still going to have problems regardless if it's flooded cable or not. There is just no way to protect against LARGE punctures or severe damage aside from conduit. > 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. > In this scenario, the coax would have one intact (outer) braid, and one > oxidized (inner) braid, at least for some distance from where the water > entered. Any thoughts on the consequences if this should occur? I would expect this to be minor unless it got bad enough to start increasing the loss of the cable. You might get some extra noise on receive though. If you're running DC powered things like preamps or relays with the cable the DC current may exacerbate the problem with the oxidation of the shield. > And is all quad-shield flooded coax manufactured with just the outer braid > flooded? As far as I know, yes, and this goes for all other cables too since the floodant is only intended to protect against water ingress due to damage to the outer jacket. The only type of cable I'm aware of that essentially has flooding compound all around is loose-tube fiber optic cable where the glass strands reside within buffer tubes that are literally filled with the flooding compound. I've never seen any kind of electrical cables manufactured this way. -Bill _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
