[c-nsp] DS3 Cables

[Antonio Querubin]

On Sun, 27 May 2007, Jon Lewis wrote:

>> What's wrong with RG-59?  As far as I understand, the most important
>> thing is "impedance 75 Ohms", which RG-59 fulfills...
>
> I guess it is the right impedance, but I've never seen it used in a telco
> facility.

There are good reasons for that.  Telcos are more concerned with signal 
loss/interference, fire safety codes, and coexistance with other cables in 
conduit.  The higher quality cables are better shielded and lower 
attenuation, are plenum-rated, and have tougher abrasion resistant jackets 
to deal with such issues.  For short jumper connections between equipment 
where the cable does not go into any plenum, RG-59/62 works fine.

Regardless of the cable type, the BNC on the ends need to match the cable 
and secured well as that's really where you're likely to have the most 
issues.  I've run into DS3 cables made by various professional cabling 
companies whose ends come right off just by lightly tugging on the BNC. 
They're put together either by inexperienced assemblers who don't check 
the quality of their work or who use the wrong connector for the cable. 
In practice if you suspect a flakey DS3 cable, you're more likely to find 
a bad crimp rather than bad 'cable'.


Antonio Querubin
whois:  AQ7-ARIN