6.1 -- 25,000 Watts
Arinc 700 radars, which began production in 1981, are less than 150 watts peak power, which is less than 1 watt rms, heating power. Your kitchen nuke is on the order of 750 watts rms.
If your old airliner's WX radar has a standby mode, then it is usually a high powered, pre-Arinc 700 radar. Only TWA kept the Standby mode when they transitioned to Arinc 700 radars, to minimize pilot training.
Have you ever thought about DME?
GB