[time-nuts] TAPR TICC boxed

Bruce Griffiths bruce.griffiths at xtra.co.nz
Tue Apr 4 07:23:05 EDT 2017


http://www.spacetechexpo.eu/assets/files/2015/Recent-Developments-in-Phase-Stable-Cables.pdf

is a more readily accessible source of data on coax cable delay tempco et.

Bruce

> 
>     On 04 April 2017 at 00:13 Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
> 
>     Copper jacketed low density PTFE insulated coax cables typically exhibit a net phase change of over 1000ppm during the PTFE phase transition. See figure 2 p14 of the Cables and connectors supplement to March 2017 microwave journal. Solid PTFE insulated cables exhibit an even greater (2 -3x) phase change. to achieve a phase shift tempco of 10ppm/C either hermetically selaed silicon dioxide powder insulated coax or "phase tracking" semirigid or better phase tracking flexible coax is required.
> 
>     Bruce
> 
>         > > 
> >         On 03 April 2017 at 21:22 Attila Kinali <attila at kinali.ch> wrote:
> > 
> >         On Mon, 3 Apr 2017 15:05:55 +1200 (NZST)
> >         Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
> > 
> >             > > > 
> > >                 > > > > 
> > > >                 For even more fun you could try to detect the PTFE phase change at around 20C using a cable with PTFE dielectric.
> > > > 
> > > >                 This will require several 100 meters of cable to be measureable with
> > > >                 the TICC. Modern cables are all <500ppm/K, good cables <10ppm/K, phase
> > > >                 stable cables reach even <1ppm/K. Measuring a change of 10ppm with
> > > >                 a resolution of 60ps means that the delay has to be in the order of 6┬Ás,
> > > >                 which is close to 1000m of cable. Even if dithering gives another facor
> > > >                 of 10, this still means 100m of cable.
> > > > 
> > > >             > > > 
> > >         > > 
> >         For this level of comparison I would suggest to use a sinusoidal signal,
> >         instead of a pulse, and do phase comparison, which gives a resolution
> >         in the order of 1ps with very little effort, thus reducing the required
> >         cable length to 10-20 meters.
> > 
> >         Attila Kinali
> > 
> >         [1] "Temperature Stability of Coaxial Cables", Czuba and Sikora, 2011
> >         http://przyrbwn.icm.edu.pl/APP/PDF/119/a119z4p17.pdf
> > 
> >         --
> >         It is upon moral qualities that a society is ultimately founded. All
> >         the prosperity and technological sophistication in the world is of no
> >         use without that foundation.
> >         -- Miss Matheson, The Diamond Age, Neil Stephenson
> > 
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