Topband: CAT5 for Flag Antenna Feedline ?

[Jim Brown]

On 9/9/2013 9:17 AM, ZR wrote:
> Would shielded CAT5 be useable as a Beverage feed? It would be easy 
> enough to match with a binocular core at both ends and I just happen 
> to have about 300' doing nothing. 

If terminated balanced on both ends, as you're describing, there's 
probably no advantage to having a shield. Indeed, the presence of the 
shield, and the other three pairs, might make things worse.

On the other hand, there are good uses for shielded CAT5 with connectors 
and equipment that has proper termination for the shield.  One of the 
chronic issues with wired Ethernet is radiation from the cable, and 
shielded CAT5 can greatly reduce it.  N6TV reported excellent 
suppression with shielded CAT5. That radiation is a combination of 
broadband hash and birdies at various discrete frequencies. The birdies 
are from clocks in each router or switch, so they differ slightly from 
one box to another. I use the birdies as indicators of how well I'm 
suppressing the overall level of trash. Two birdies I use are around 
14030 and 21052 kHz. If you have neighbors, you'll often hear multiple 
birdies, so I kill power to my Ethernet switch to see which one is 
mine.  Some of the radiation is common mode, so it can be killed with 
chokes on the Ethernet cable and power cable. But some is often coming 
directly from the box, due to poor circuit layout and poor shielding, 
and not much can be done without making it a science project.

73, Jim K9YC