Not sure if this helps but take a look at this site.
RAF Chivenor Air Day 1993 (?)
Scroll down and lots of 1993 shots of a radar head.
Also
RAF Chivenor 1980's - Britmodeller.com
Scroll down to the Dominie 1981. Same radar head?
If this is what you are looking for the site is further east possibly:
51°05'07.21" N 4°09'00.38" W
I believe the site you are suggesting is/was the Fire Section burning area