I did some very rough measurements last summer with. Run of LMR-400 that was laying on the roof in the hot Georgia sun. Using a network analyzer to "ping" the cable I found the day vs. night delay difference was pretty much in the noise. I'll see if I can find the details and if so will post them.
I found via google a brief paper from Haystack that measured LMR-400 and LMR-240 and found in the range of -11 to +17 ppm/K of the total cable delay. They note that 9 ppm/K is about 3ps/degree in 100M of cable: http://www.haystack.mit.edu/tech/vlbi/mark5/mark5_memos/069.pdf However, there's another possible tempo contributor that I suspect could be a significant contributor, and that's the preamp up in the antenna, particularly if it has a bandpass filter. It wouldn't surprise me at all if preamp/BPF tempo was noticeable. John On Oct 16, 2011, at 1:32 PM, "WarrenS" <[email protected]> wrote: > Anyone know what the propagation delay temperature coefficient is for RG6U > coax and how much it varies between different brands of cable? > > In my efforts to improve the Tbolt's performance to make it into a better Cs > substitute, > test suggest that the temperature coefficient of the antenna lead-in cable's > propagation delay is contributing to diurnal errors. > > Anyone have a idea for a SIMPLE & cheap voltage controlled delay line that > can be changed by a few ns as a function of the outside air temperature? > > As an alternative, Mark, want to consider adding another LadyHeather feature > that tweaks the Tbolt's cable delay value as a function of the outside > temperature? > If interested, I have a couple ideas of how to get the outside temperature to > LadyHeather. > > ws > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
