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7A12: Difference between revisions
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The [[7A12]] uses the [[155-0032-00]] custom IC as a gain stage and the [[155-0022-00]] for channel switching. | The [[7A12]] uses the [[155-0032-00]] custom IC as a gain stage and the [[155-0022-00]] for channel switching. | ||
[[John Addis]] writes: There were two mistakes, concept errors, that doomed the 7A12 from day one. The first was in deciding to use the 1 GHz F<sub>T</sub> Tektronix IC process (called 50/450 for resistivities of the two base layers) for the signal path. This process was Tektronix' fastest but too slow for a plugin expected to provide 150 MHz bandwidth in the fastest original mainframe, the [[7704]]. At the time, HP had a 2.5 GHz process used in the 1830A, 250MHz plugin. | [[John Addis]] writes: There were two mistakes, concept errors, that doomed the [[7A12]] from day one. The first was in deciding to use the 1 GHz F<sub>T</sub> Tektronix IC process (called 50/450 for resistivities of the two base layers) for the signal path. This process was Tektronix' fastest but too slow for a plugin expected to provide 150 MHz bandwidth in the fastest original mainframe, the [[7704]]. At the time, HP had a 2.5 GHz process used in the 1830A, 250MHz plugin. | ||
The second day one mistake, later pointed out by [[Tom Rousseau]], was to arrange the two channels side by side. Roy wanted to be able to go from one sensitivity (deflection factor) to another without having to go through all the sensitivities in between as happens with a rotary switch. The vertical row of push buttons was functionally attractive. However, that would require both channels to occupy the same space if on a single, centered, vertical circuit board. | The second day one mistake, later pointed out by [[Tom Rousseau]], was to arrange the two channels side by side. Roy wanted to be able to go from one sensitivity (deflection factor) to another without having to go through all the sensitivities in between as happens with a rotary switch. The vertical row of push buttons was functionally attractive. However, that would require both channels to occupy the same space if on a single, centered, vertical circuit board. | ||