Topband: Power / Control cable

[Eric NO3M]

I'm in the process of finding a replacement cable to supply power 
(+24VDC) and differential serial signaling (RS-485) to my remote RX 
switching matrix and vertical arrays.  Total run is about 600ft. The 
original cable was outdoor rated, gel infused CAT5 using 3-cond for 
VDC+, 3-cond for VDC-, and the remaining two cond for serial. It lasted 
almost 7 years.

Recent searches for a reasonably priced replacement CAT5 have brought up 
a lot of candidates, but with CCA (copper clad aluminum) conductors.  
I'd prefer pure copper as far as the power lines are concerned, but 
price increases dramatically.

Any recommendations on a suitable and decently priced cable to do the 
job, supplier?  Perhaps parallel runs of 18/2 or 16/2, 18/4 or 16/4, or 
a good deal for CAT5 with pure copper?

Thanks
73 Eric NO3M