Secure Telephone Unit
S T U
T E L C O
Telephone Company
T r a n s m i t
T x
United Kingdom
U K
U L
U n d e r w r i t e r s
V o l t s
V
Volts, alternating current
V a c
Voice Operated Switch
V O X
V o l t s P e a k - T o - P e a k
V p p
V r m s
Volts root-mean-square
B - 4
