Radar detection ranges for British DD's, DE's
 

I'd like to find out when (year) radar units began to be placed on British DD's and DE's during the war. Second question: what range could they used at and how effective were they against surfaced uboats. As usual, I thank you guys in advance.

I got my radar detector in 1942, so I'm guessing they have them then, possibly even earlier. In 43 they definitely do. Not sure about range, but from my experience my detector doesn't so much allow deterrence from destroyers as enough time to prepare. The destroyer will probably know about where you are, but you have enough time in advance to dive deep, slow down, silent run, and creep about until they move on.

Not sure about any others, but I do know that the NYGM tonnage war supermod fixes to more historically accurate the radar detection ranges of the different radar detector types.

Radar appears in 1940 in the stock game but not all DD's are equipped. I'm not sure how the decision is made as to what has it what doesn't. Not sure on the ranges