[time-nuts] Non-impedance matched antenna cables
Bruce Griffiths
bruce.griffiths at xtra.co.nz
Sat Jun 14 01:52:35 UTC 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.
>
Mark
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.
Bruce
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