[HCARC] What To Run To THe Shack For Feedlines

[Kerry Sandstrom]

Gary,

I don't know what you mean by electrical cables.  You can probably run a low 
voltage (12 VDC) control line in with the coax.  I think that running a 120 
VAC line in with the coax is very very unsafe.  I'm sure it also violates 
any applicable codes, too.  Yes, if you have other wires running beside the 
coax cable there will be some coupling between them.  If there is any RF on 
the outside of the coax, it will couple to any other conductors in the 
conduit.  You should be able to find reports on coupling between the 
conductors in shielded cables like coax.  Cat 5 and Cat 6 cables are 
shielded twisted pair.  I'm sure that the coupling between those data cables 
and coax has been characterized, but I don't know what the numbers are. 
Coupling between cables was a common part of EMI/EMC work.  The fact that 
they make double shielded cables is reason enough to believe there is 
coupling between cables.  Unfortunately, I don't have any of the data handy. 
However just think about the levels in potentially adjacent cables, a 
receiving cable may have signals as low as -110 dBm or less.  A kW 
transmitter might be putting a level of +60 dBm.  Your cable is 150 feet 
long.  The required isolation is 170 dB, a big number.  A digital data cable 
may be running 1 V level signals in a 100 Ohm impedance, its level is +10 
dBm.  That's 120 dBm above weak signals going to the receiver.  Digital 
signals have lots of HF and VHF frequency content.

Kerry