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Distributed deflection plates: Difference between revisions
Distributed deflection plates (view source)
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The lumped delay line is terminated at the end of the deflection structure outside the CRT. 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 transmission line has absorbed the plate capacitance. This means the vertical amplifier is driving a resistive load and not the capacitance of a long deflection plate. | The lumped delay line is terminated at the end of the deflection structure outside the CRT. 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 transmission line has absorbed the plate capacitance. This means the vertical amplifier is driving a resistive load and not the capacitance of a long deflection plate. | ||
Note that the last deflection plates are often tilted and farther apart than the others. This is to prevent the deflection plates from intercepting and cutting off the electron beam at large deflections. The famous 545A's CRT has only 4 divisions of deflection because of vertical deflection plate interception. | |||
[[File:Tek7844-v-b2.jpg|300px|thumb|right|Vertical termination resistor (l) and amplifier (r) in a [[7844]]]] | [[File:Tek7844-v-b2.jpg|300px|thumb|right|Vertical termination resistor (l) and amplifier (r) in a [[7844]]]] | ||