In particular, the reference unit can either be connected directly to the reference junction with its connector screwed into the lower threaded cavity 64 or, as shown in FIGS 5 and 7, {TAIL ~ the reference unit} can be connected indirectly to {HEAD ~ the reference junction} by a coaxial adapter 68 and a coaxial cable 49 
In particular , the reference unit can either be connected directly to the reference junction with its connector screwed into the lower threaded cavity 64 or , as shown in FIGS 5 and 7 , { TAIL ~ the reference unit } can be connected indirectly to { HEAD ~ the reference junction } by a coaxial adapter 68 and a coaxial cable 49
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