Adjustable Attenuator Board

TM 11-5805-451-15

which cause two signals from input port 1 to reach output port 1 out of phase. The

65-dB loss between any input and the other inputs is due to the two equal-loss paths

connected so that the signals arrive 180 degrees out of phase.

The adjustable attenuator board, Philco part No. 368-42056, used in the

Express Orderwire Multidirection Unit consists of five 600-ohm "H" pads of 1 dB,

2 dB, 4 dB, 8 dB, and 16 dB. By strapping various combinations of these pads,

any value of attenuation between 0 and 31 dB can be obtained in 1-dB steps.

Voice-Frequency Amplifier Board

The voice-frequency amplifier board, Philco part No. 368-41965, used in

the unit incorporates ultra-stable two-transistor amplifiers with a transformer-

coupled input and output impedance of 600 ohms. The amplifiers can accept signal

levels from -40 to 0 dBm and have a maximum output level of +10 dBm. They

provide a maximum signal gain of 30 dB, and the gain is variable down to 0 dB.

Two amplifiers, designated as "A" and "B" units, are mounted on each voice-

frequency amplifier board with the "A" unit gain control at the top and the W" unit

gain control at the bottom when the board is inserted in its connector. (Refer to

figure 7-6. ) There are seven test points provided on each amplifier-board. The

black test point is the dc and signal common. The output test points are either red

and orange or yellow and green. The input level is measured between either brown

or blue and common.