You are likely correct. I have not reviewed the spec in some time, but it most likely is an average value over the LAN-used spectral range (likely in the high-kHz region up to maybe 100MHz or so). It is the only standardized measurement for crosstalk on cat-x cable types that I'm aware of though.
Regarding the indoor-rated cable being used outdoors, there is flooded outdoor-rated cable available and it's not much different in cost from the usual riser-rated indoor cables. The outdoor-rated cable usually has a black PE jacket and a floodant inside. I recently came across a new "dry" (non-flooded) outdoor cable that has a non-halogen jacket (read that as "expensive but safe in a fire") and a foil shield. It has an outer jacket, a shield with drain, an inner jacket, and then the usual 4 cat5E pairs. I think the cost was in the general area of about 25 cents/foot though which likely precludes it's use for "cheap" feedlines though :-) If you need a "cheap" cable to use outdoors, the use of BLACK RISER-RATED (CMR) cable would be OK as it tends to hold up reasonably well although the jacket will eventually form cracks. DO NOT use plenum-rated (CMP) cable as it has a very short lifetime when used outdoors, IME. Personally, I try to just match everything to 75 ohms so that I can use RG6 cable. RG6 is cheap and available and easy to get in a true outdoor-rated cable. -Bill > On 4/14/2011 10:33 AM, Bill Wichers wrote: > > There is a test used when installing this cable commercially called > > "PowerSum NEXT". If you look that up you should be able to get an idea > > of the coupling between pairs. > > These are most likely to be single-number values that average the > crosstalk over a broad frequency range, but the actual performance will > vary as a function of frequency, and with the quality of the cable. I > haven't done measurements, but I would expect cross-talk to be lower > (better) at 2 MHz than at higher frequencies. Published loss data for > CAT5/6 shows numbers good enough for use with RX antennas. > > That said, the primary consideration is probably what Herb noted about > how well (poorly) indoor-rated cable is likely to stand up to outdoor > conditions. Although I love CAT5/6/7 for lots of uses, I wouldn't use > it for outdoor runs to antennas. > > The best choice for Beverages and other RX antennas is low-cost coax > like RG58s or RG59s, with construction that makes them rated for the > outdoor conditions where you live. > > 73, Jim K9YC > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
