[time-nuts] T.I. experimenting - newbie question

[Magnus Danielson]

On 04/03/2011 11:52 PM, Joseph Gray wrote:
> That's an interesting question. Does temperature have an effect on the
> dielectric that changes the VOP? I'll have to try your experiment. Is
> that worth ten extra credit points? :-)
>
> The copper in the coax has a positive temperature coefficient, which
> will contribute to an increased impedance (assuming the reactive
> components don't change). But, does the impedance have any effect on
> VOP? A quick Google search didn't find any information on this. AFAIK
> VOP is due to the dielectric properties.

Yes, and the dielectric properties change with temperature and hence 
will the speed of the signals. Blow bubbles in the dielectric and the 
speed goes up and dependence of temperature goes down.

Same thing happens with fibre. As I recall it about 1/10 of the shift 
was due to becoming longer from heat and the rest from the dielectric.

Cheers,
Magnus