The MAC Card is a 6-layer PCB, 233mm by 280mm in size, 1.6mm thick with 35µ copper plating on all layers. The construction of the PCB is shown in figure. The MAC card is designed with 8mil track width and 8mil track-to-track spacing. The via size used is 16mils. The MAC Card uses two 160-pin Euro Connectors ( 5 rows X 32 pins ) to connect with the backpanel. Both, the input and output to be card is through these 320-pins. The MAC backpanel is actually a Backpanel system . built around a 3.2mm, 16 layer PCB whose construction is shown in figure. The backpanel system is made up of a set of four different cards. Three sets of smaller auxilliary cards plug into the 16-layer PCB which is used as the backpanel for the MAC and MAC Control cards. Two out of these three are essentially SMT-to-DIP adapters for the 50-mil X 50-mil AMPMODU Surface Mount connectors which receive the FFT outputs. The third is a termination card carrying line-to-line and line-to-ground terminations for the ECL signals. In all, 23 of the SMT-to-DIP adapters are used omthe backpanel. Seventeen of these occupy the center of the MAC backpanel "SMT-to-DIP adapters" while the other 6 plug-in horizontally into the upper and lower ends of the backpanel. The termination card too, like the adapter, plugs-in orthogonal to the plane of the backpanel. A total of 66 MAC cards are required for the entire system. Each backpanel supports 11 MAC Cards in addition to one MAC Control Card and one free slot. The inter-card spacing is of 6T ( = 1.2 inch ). Thus, a total of 6 subtracks make up for the entire requirement. Each MAC subrack is housed along with the FFT subrack and the distribution subrack in one of the 6 FX racks. Each distribution subrack supports 5 distribution cards. A total of 6 such subracks housing in all 30 distribution cards are required for the entire system. The arrangement of various subracks as well as the power-supply and fan tray are shown in figure.
GOBACK TO MAC SUBSYSTEM