[time-nuts] How phase stable is rg59 or alternate coax

David G. McGaw david.g.mcgaw at dartmouth.edu
Tue Nov 22 09:19:35 EST 2016


Note that partial air core (9913) and foam dielectric is better than 
solid polyethylene.

David N1HAC


On 11/21/16 5:39 PM, Mark Spencer wrote:
> At one point I contemplated running Andrews "Heliax" for my GPS antenna.   Part of the rationale was due to the data presented in page 2 of the following paper.
>
> http://ivs.nict.go.jp/mirror/meetings/v2c_wm1/phase_stability.pdf
>
> I subsequently decided to stay with my existing run of plenum rated RG58.  The bulk of my cable run is indoors where the temperature is fairly stable.
>
> Regards
> Mark Spencer
>
>
>
>> On Nov 21, 2016, at 12:59 PM, Scott Stobbe <scott.j.stobbe at gmail.com> wrote:
>>
>> When I first took a look at some of the coax datasheets I couldn't find
>> anything. I was able to find the following paper "phase stability of
>> typical navy radio frequency coaxial cables"
>> http://www.dtic.mil/dtic/tr/fulltext/u2/628682.pdf I attached the table
>> from the last page. They estimate RG59 to have a tempCo of -330 PPM/degC
>> for electrical length. They also estimated RG-58 at -480 PPM/degC.
>>
>>> On Mon, Nov 21, 2016 at 2:44 PM, John Ackermann N8UR <jra at febo.com> wrote:
>>>
>>> I can't find the data right now, but will keep digging.  There's also a
>>> short paper from the early 2000s from Haystack on their measurement of
>>> LMR400 in an environmental chamber.  They came to the same conclusion, but
>>> I can't find that paper either. :-
>>
>> John, many thanks for the Haystack tip! That is a wonderful paper, I
>> believe the one you are quoting is "Dispersion and temperature effects in
>> coax cables" http://www.haystack.mit.edu/tech/vlbi/mark5/mark5_memos/067.pdf
>> <PhaseTempCo_Coax.png>
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