The bandwidth of the electronic subsystem is a function of the circuit components, and is defined in the following manner: The lower half-power frequency is defined as the lower fre­quency at which the current gain of the subsystem is down to 70. 7 percent of the midband value; the upper half-power frequency is defined as the upper frequency at which the current gain of the subsystem is down to 70. 7 percent of the midband value. The bandwidth is defined as the difference of the upper half-power frequency and the lower half-power frequency. The lower half-power frequency is determined by the equation:

2* RL CC

where

f j = lower half-power frequency in cps Rl = load resistance of a stage in ohms, and

= coupling capacitance to this load resistance in farads.

These components are the same components as those which provide the appropriate RC clipping. The minimum RC clipping time that can be used is determined by the characteristics of the leading edge of the information pulse. In general, in order to restrict the losses of pulse height in an RC clipping circuit to the order of 25 percent of the peak input pulse or less,, the clipping time must be at least ten times the rise time of the information pulse. As described earlier, the rise time of the slowest information pulse (the pulse from the in-core detector assembly) is approximately 0. 15 psec. It is therefore necessary that the clipping time be not less than 1. 5 psec to keep the loss in height to 25 percent. A clipping time of 2 psec was selected. This results in a calculated lower half-power frequency of approximately 21 kc/sec in the first stage of the remote amplifier and in the first stage of the discriminator.

The upper half-power frequency is determined by the high-frequency components or characteristics of the circuitry. These components and characteristics are, in general, the parallel interstage resistance, the shunt capacitance, and the frequency characteristics of the active devices used. On the basis of the parallel resistance and shunt capacitance, including the stray capacity, the upper half-power point will be in the region of 15 Mc/sec to 30 Mc/sec.

Considering a single stage with the type of transistor used in the amplifier stage of the

subsystem, the upper half-power frequency due to beta fall-off will be 7 Mc/sec minimum.

With five similar stages, the upper half-power point will be reduced by the additional breaks, and

(71

as described in Petit and McWhorter, ‘ ’ the new upper half-power frequency f’2 is given by