A Data Communication Historical Series
By Bob Pollard
Seattle Washington 1953 – 1957: The following diagrams/drawings are a few samples of the 50 or so drawings I composed during my days as a Wire and Repeater Technician.
The first three drawings represent the contacts, coils and wiring of relays / repeaters used in the Seattle office.
Click the diagram to enlarge, use back button to return
The following diagram represents a 1950s jack matrix used for routing, re-routing, removing, and/or replacing component parts of a carrier system.
1. The frequency tuner, which is necessary for modulation or demodulation of the carrier frequency. 1A is part of the tuner.
2. The carrier frequency (oscillator) for the modulator or demodulator.
3. On the receive side, to the carrier device, this would be a power amplifier.
4. On the send side, from the carrier device, this would be a ‘pad’ (power reducer).
5. The jack connected to the carrier device for transmitting (send) to the telephone line.
6. The jack connected to the carrier device for receiving from the telephone line.
7. The jack connected to the frequency tuner on the transmitting (send) line and strapped to jack 5 to complete the circuit.
8. The jack connected to the frequency tuner (1A) on the receive line and is strapped to jack 6 (to receive carrier) to complete the circuit.
9. The jack connected to the frequency tuner on the telephone channel side and is strapped to jack 10 to complete the circuit.
10. Jack 10 is connected to the amplifier (3) on the receiving side of the line. On the send (transmitting) side of the line jack 10 is connected to a ‘pad’ (power reducer) (4). Jack 10 is strapped to jack 9 to complete the circuit.
11. Jack 11 is connected to the amplifier (3) on the receiving side or the pad (4) on the send side. Jack 11 is strapped to jack 12 to complete the circuit.
12. Jack 12 is connected to the telephone channel (line), one for sending and a second one for receiving since sending and receiving functions must be separated, which requires two channels (lines). Jack 12 is strapped to jack 11 to complete the circuit.
13. Jack 13 is a jack used for connecting test equipment; includes an isolation pad (coil).