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Distributed deflection plates: Difference between revisions
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The end of this delay line needs to be terminated to prevent the drive signal being reflected back through the line. In Tektronix scopes, the termination resistor can often be seen attached to a second pair of vertical deflection terminals on the side of the CRT, which bring out the end of the transmission line. | The end of this delay line needs to be terminated to prevent the drive signal being reflected back through the line. In Tektronix scopes, the termination resistor can often be seen attached to a second pair of vertical deflection terminals on the side of the CRT, which bring out the end of the transmission line. | ||
Distributed deflection plates reduce the capacitance seen by the driving amplifier, however, the terminated transmission line presents a much lower impedance than unterminated capacitive plates would. While better matched to semiconductor amplifiers, driving low impedances from tube amplifiers presented challenges, as cathode followers were not able to provide sufficient bandwidth. The problem was solved - at quite some expense - by using a [[distributed amplifier]]. | |||
==History== | ==History== | ||
Distributed deflection plates were introduced in the [[580-series scopes]] in the late 1950s. Transistorized scopes followed with the upgrade of the 50 MHz [[453]] to the 150 MHz model [[454]] in 1967. | Distributed deflection plates were introduced in the [[580-series scopes]] in the late 1950s. Transistorized scopes followed with the upgrade of the 50 MHz [[453]] to the 150 MHz model [[454]] in 1967. | ||
Typically, only the vertical deflection plates are distributed. An exception is the [[7104]] due to the high | Typically, only the vertical deflection plates are distributed. An exception is the [[7104]] due to the high horizontal system bandwidth required (350 MHz). | ||
==Literature== | ==Literature== | ||