Has a thermostatically controlled block heater. NRAO has installed heaters in this NRAO supplied equipment which are switched on and off by a humidistat. I doubt that it has any special low RFI features. Probably John Ford has the most recent word on this. My guess is that this will be thermostat controlled.
Most concern is for the ones that go on and off located at the top of the feed arm.
These are incandescent and were tested and approved by NRAO regarding interference. However, there was never a report written and no information was given as to the testing conditions, in spite of mine and Fleming's insistence. B. Telescope drive motors, clutches and brakes- total of 24 of these assemblies, plus a number of motor drives around the feedroom, although these are brushless. Numerous possibilities of interference. In my experience, these are not a problem, since the designer has to worry about interference levels that could induce false triggering and instability.