31,934
edits
556: Difference between revisions
→Challenges in the Vertical Signal Path
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<!--A pair of 8608 tubes. (temporary photo)--> | <!--A pair of 8608 tubes. (temporary photo)--> | ||
[[File:Two 8608 tubes.jpg|thumb|A pair of 8608 tubes.]] | [[File:Two 8608 tubes.jpg|thumb|A pair of 8608 tubes.]] | ||
[[File:Tek 556 vert amp output.jpg|thumb|Vertical output tubes. The beige rectangular components are 1kΩ plate resistors. In addition to reducing parasitics, moving the anode connection to the top on the 8608 tube allows the plate resistors, which dissipate a few watts, to be in the air stream from the fan.]] | |||
<!--Vertical output tubes. The beige rectangular components are 1kΩ plate resistors. In addition to reducing parasitics, moving the anode connection to the top on the 8608 tube allows the plate resistors, which dissipate a few watts, to be in the air stream from the fan.--> | <!--Vertical output tubes. The beige rectangular components are 1kΩ plate resistors. In addition to reducing parasitics, moving the anode connection to the top on the 8608 tube allows the plate resistors, which dissipate a few watts, to be in the air stream from the fan.--> | ||
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where the Delco DTG2400 PNP transistor was the only suitable part available. | where the Delco DTG2400 PNP transistor was the only suitable part available. | ||
After a break at serial number 2000, a major mod replaced the germanium parts with a design incorporating newly available silicon devices. | After a break at serial number 2000, a major mod replaced the germanium parts with a design incorporating newly available silicon devices. | ||
An aside – in the design of bleeding-edge electronic equipment, there can be a few bright ideas, | An aside – in the design of bleeding-edge electronic equipment, there can be a few bright ideas, | ||
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driven by the differentiated positive-going ramp, boosts the pull-down current, keeping the cathode follower in conduction. | driven by the differentiated positive-going ramp, boosts the pull-down current, keeping the cathode follower in conduction. | ||
Our circuit had been inherited from the 544-546-547 ‘scopes, and when I questioned the designer about the effect, | Our circuit had been inherited from the 544-546-547 ‘scopes, and when I questioned the designer about the effect, | ||
he said, “I always wondered … “. Some fiddling with currents and time constants diminished the effect. | he said, “I always wondered … “. Some fiddling with currents and time constants diminished the effect. | ||
===Brought to Market=== | ===Brought to Market=== | ||