[Antennaware] unknown coax cable

K9AY k9ay at k9ay.com
Thu May 22 09:46:33 EDT 2008


Does the coax have two shields -- e.g. is there a shield around the inner 
dielectric, then the second dielectric, and another shield over that? If so, 
it's "triaxial" cable with an isolated shield for hum reduction. It's video 
cable, so it's 75 ohms (+/-). For RF, you can affix the connector to both 

If the two dielectrics are adjacent, then I don't know for sure. The second 
layer could be a stiffener. The only two-layer dielectric I've seen is a 
spiral "semi-air" inner dielectric with a solid dielectric sheath around it 
to support the shield braid.

I'd also check to see if it's fiber optic cable. They usually have multiple 
layers, and the conductors might be there for armor or DC supply.

73, Gary

>i have a roll (500 foot) of coaxal cable.. it has two (2) inner
> deilectric's, one the normal looking cloudy white on the inner conductor
> es wtth a black outer on the cloudy white one, then the plated/tinned?
> outer braid very heavy type ,then the black outer..the inner core is multi
> approx 48 x 0.25mm total inner wire core is 2.1mm OD of c/white insulation
> is 5.1mm the OD of the black insulation is 8.1mm  then the heavy braid es
> the outer cover is 10.7mm .. its not 50 ohms!! wot or how can i find out
> what it is ohm es VF% ..tU VK3PA

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