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.
Adjustable Attenuator Board
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-
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.