On 4/8/2020 10:37 AM, Lee STRAHAN wrote:
Good morning from Oregon Top-Band people,
Cable loss was -.61 dB at 59 Deg. F, And -.58 dB at an averaged cable
temperature of 23 Deg. F.
59 Deg. F 23 Deg. F
1 - 74.59 DEG -74.60 DEG.
2 - 74.59 DEG -74.60 DEG.
3 - 74.59 DEG -74.60 DEG.
4 - 74.59 DEG -74.60 DEG.
5 -74.60 DEG -74.60 DEG.
6 -74.60 DEG -74.60 DEG.
7 -74.60 DEG -74.60 DEG.
8 -74.60 DEG -74.60 DEG.
9 -74.60 DEG -74.60 DEG.
10 -74.60 DEG -74.60 DEG.
My bottom line conclusion is that for our purposes on the top-bands I no longer
wonder if the cable delay and attenuation remained constant with winter
deployed arrays.
Incidentally, T&B Snap and Seal have been the best connectors here for
repeatability.
Lee Strahan
K7TJR
These numbers seem too good to be true.
The tempco works out to less than 7 PPM/°C.
Consider that the coefficient of thermal
expansion of copper is +17PPM/°C.
Refer to Figure 7 of this:
https://www.timesmicrowave.com/DataSheets/Literature/Current%20innovations%20in%20phase%20stable%20coaxial%20cable.pdf
The graph on the right shows non-linear tempco curves.
When you have non linearity like this,
it is possible to pick two points on the curve
such that a line drawn through them has a slope of zero.
Maybe you ran into that.
The numbers you reported for the loss seem roughly
consistent with what the thermal coefficient of
resistance of copper predicts.
Rick N6RK
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