Smithy:
[quote]Cold-soaking a radar at -40C for a period of time and then powering it on (therefore heating it up) will subject the components to significant thermal stress and will very quickly cause failure. /QUOTE]
Astute avionics manufacturers have always stressed incoming components at . . . . -40C . ., to knock out the ones that will fail prematurely. (That's part of why avionics are so expensive.) Wx radar antennas are designed to operate either occasionally or continuously at altitude, whether started warm or cold. Typically they average more than 10,000 hours flight time between unscheduled removals.
Some airlines automatically remove the antennas for lubrication and replacement of components that wear out at less than 10,000 hours, so their MTBUR, Mean Time Between Unscheduled Removals is much higher. Running the radar continuously will wear out the antenna pointing mechanism sooner, guaranteed.
The Wx radar transceiver has no moving parts, and is inside the pressure vessel in transport category aircraft, so not subject to extreme temperatures, of course.
How much does it cost to operate the Wx radar? Probably on the order of $1 per flight hour.
Some pilots find the radar return on the Nav Display to be a nuisance, and turn the intensity down to 0. It would be better to just turn it off.
Historically, UAL has been the only carrier to provide adequate Wx radar training to pilots.
GB