Another possibility is that the cable is straightening. The cable had only been unwound that morning, having been in a circular shape during shipping and with the cavity hanging from it, it could be slowly straightening (and moving forward?). When we run the 5-min-off, 90-sec-on, 5-min-off test in a couple days, the results will be more definitive because, by then, the cable should be in equilibrium.
Any other things that could cause such a slow uni-directional movement that you can think of?
I have started a list:
- Coax cable straightening
- Air currents – easy fix, enclose the shelf.
- Coax cable heating – more thoughts on this – if we start the experiment with the coax cold, and it still moves through out the entire duration, that suggests heating is less likely to be a cause.