[time-nuts] Non-impedance matched antenna cables

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jun 13 21:52:35 EDT 2008

Mark Sims wrote:
> Of course,  any Time Nut worth the name would install a servo controlled section of trombone line in his coax to maintain a constant electrical length ;-)
> ----------------------------------------
> This demonstrates that achieving nanosecond propagation delay stability 
> is unlikely when using long runs of inexpensive cable exposed to diurnal 
> temperature cycling.

Since temperature cycling is often used to stabilise the phase 
shift/delay of coax delay line assemblies even when using phase stable 
cables, the question that arises is:
Does the electrical length continue to change with time or does it 
stabilise after a number of diurnal temperature cycles?
Or should one temperature cycle (3 or more times) the cable over a wider 
range than the ambient temperature fluctuations?

If one doesn't temperature cycle hardline the dielectric can protrude 
from the ends when exposed to diurnal temperature cycling and break the 
coax connector solder connection.


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