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

[Jim Lux]

The electrical length of a piece of coax does change with temp.
The Gore catalog, for instance, has a graph of it.  And it has a most annoying bump right around 20 to 25 C, at least for the stuff I use at work.

As to why... The length changes for one thing. I think, also, there will be a change due to the change in diameter, as well as the density of the dielectric, which will change the capacitance per unit length.

On Apr 3, 2011, at 14:52, Joseph Gray <jgray at zianet.com> 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.
> 
> Joe Gray
> W5JG
> 
> On Sun, Apr 3, 2011 at 3:21 PM, Bill Hawkins <bill at iaxs.net> wrote:
>> For extra points, test with the same long cable at different
>> temperatures.
>> Say from soaking in a 150 deg F oven and a zero degree freezer.
>> Bill Hawkins
>> 
>> 
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