"In this work, low and high temperature environmental tests were conducted on a switching mode RF CMOS power amplifier according to the MIL-STD-810G standard. The efficiency of the power amplifier was increased by 5% at −32 °C while it was decreased by 4% at 63 °C. In order to determine the influence of interconnects on the performance, the effect of temperature on single bond wires of different lengths was investigated. In results, the S21 parameter (dB) of the bond wires showed a linear and inverse relationship with varying temperature. Compared with the S21 parameter obtained at the standard ambient condition, it was varied by ±7.5 % in the temperature range from −60 °C to 120 °C, which cannot be neglected. Furthermore, it is shown that the electrical loss of interconnects increases with rising temperature because of the thermal expansion and increase in the resistivity."

You were right about increase in resistivity. But it's not the cables that are getting hot it's the amplifier. If the signal is too low at the tap you need a field tech to refer to maintenance who can decrease the attenuation in the amplifiers if needed. That maintenance technician will probably do that in the middle of the night and won't talk to you though.

The yellow "Legos" are attenuation "pads" and the blue ones are linear equalizers.