 The Mk . IV was a complex lash @-@ up of systems , known collectively in the RAF as the Airborne Radio Installation 5003 ( ARI 5003 ) . Individual parts included the R3066 or R3102 receiver , T3065 transmitter , Modulator Type 20 , Transmitter Aerial Type 19 , Elevation Aerial Type 25 , Azimuth Aerial Type 21 and 25 , Impedance Matching Unit Type 35 , Voltage Control Panel Type 3 , and Indicator Unit Type 20 or 48 . 
