L3 coaxial system - Amplifiers

The line amplifiers for the L3 coaxial system are designed to compensate for the loss of the 4 miles of cable which separate the repeaters; the flat amplifiers are used to compensate for equalizer loss and as transmitting amplifiers. The two types are basically similar, consisting of two feedback amplifiers in tandem, separated by an interamplifier network; in the line amplifier, this network is variable, and is automatically adjusted to compensate for variations in cable temperature, and for small deviations from the nominal 4-mile spacing.