[time-nuts] Measuring coax temperature coefficient with a TICC

Mark Sims holrum at hotmail.com
Sat Apr 15 01:34:12 UTC 2017


I finally got around to using a TICC to measure the temperature coefficient of 100 feet of generic RG-58 coax using a TICC.   The TICC was clocked by a HP 5071A 10 MHz output.  The 1PPS output was connected to the input of the coax and the TICC chB input.  The TICC chA input was connected to the coax output via an inline terminator.   The TICC was set to "debug" mode  and Lady Heather plotted the chB-chA timestamp difference (hence the negative cable delay values).

The coax had been chilled down for 2 hours in a 5 degrees F in a freezer,  connected to the TICC, and left to warm up in a 75 degree F room.   Over the 10F to 70F temperature range (measured with an IR thermometer) the coax delay spanned around 300 ps... so figure around 5 ps per degree F (10 ps per degree C) for 100 feet of cable.

I'm adding currently adding the ability for Heather to use an external temperature sensor... 
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