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585: Difference between revisions
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The main difference is the impedance of the signal that passes | The main difference is the impedance of the signal that passes | ||
through the interface from the plug-in to the mainframe. | through the interface from the plug-in to the mainframe. | ||
In 530/540/550-series scopes, the plug-in expects the mainframe to be a high impedance load | In 530/540/550-series scopes, the plug-in expects the mainframe to be a high impedance load, | ||
driving tube grids in the mainframe. | |||
The [[580 Series plug-in interface]], on the other hand, presents a differential transmission line | |||
input with an impedance of 93 Ω per side, going into the first distributed amplifier stage. The | |||
other end of this transmission line is returned to the plug-in for termination and biasing. | |||
The [[580 Series plug-in interface|pin-out of the interface connector]] is also different, | The [[580 Series plug-in interface|pin-out of the interface connector]] is also different, | ||
the 580-series pin-out being essentially flipped 180° from its | the 580-series pin-out being essentially flipped 180° from its 530/540/550 series counterparts | ||
530/540/550 series counterparts (''Signal Out'' is between pins 14 and 16 as opposed to between pins 1 and 3, etc.) | (''Signal Out'' is between pins 14 and 16 as opposed to between pins 1 and 3, etc.) | ||
The [[81|Type 81]] adapter allows the use of letter-series and 1-series plug-ins in a 585. | The [[81|Type 81]] adapter allows the use of letter-series and 1-series plug-ins in a 585. | ||
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made of a pair of miniature dual triode tubes. | made of a pair of miniature dual triode tubes. | ||
Starting at serial number 1071, the | Starting at serial number 1071 (and sometimes retrofitted to earlier instruments), the dual-triode | ||
10 mA [[tunnel diodes|tunnel diode]] | Schmitt trigger circuit was replaced by a 10 mA [[tunnel diodes|tunnel diode]] AC-coupled to the | ||
transistor. The | base-emitter junction of an [[OC171]] germanium PNP transistor as a pulse amplifier. | ||
The slower "B" timebase uses a Schmitt trigger circuit. | |||
=== Vertical Signal Path === | === Vertical Signal Path === | ||
Like the [[545]], [[551]], and [[555]], the 585 uses two [[distributed amplifier]]s in the vertical | Like the [[545]], [[551]], and [[555]], the 585 uses two [[distributed amplifier]]s in the vertical signal path, | ||
signal path, one with seven differential [[6DJ8]] stages driving a helically-wound, differential [[delay line]], | one with seven differential [[6DJ8]] stages driving a helically-wound, differential [[delay line]], followed by | ||
followed by a five-stage differential distributed driver amplifier and a [[7699]] power stage driving the CRT. | a five-stage differential distributed driver amplifier and a [[7699]] dual tetrode power stage driving the CRT. | ||
Unlike the other 500-series scopes, the 585 uses a CRT with [[distributed vertical deflection plates]], | Unlike the other 500-series scopes, the 585 uses a CRT with [[distributed vertical deflection plates]], | ||
the [[T581]], enabling it to have both high sensitivity and fast risetime. | the [[T581]], enabling it to have both high sensitivity (~5 V/cm vertically) and fast risetime, | ||
however, limiting vertical deflection to slightly over 4 cm. Total acceleration voltage is 10 kV. | |||
Several improvements were published for the 585 circuitry, including the enhanced trigger circuit. | Several improvements were published for the 585 circuitry, including the enhanced trigger circuit. | ||
If all of those changes are applied to a 585, it is essentially a 585A. | If all of those changes are applied to a 585, it is essentially a 585A. | ||
After serial number 2585, the back termination of the final distributed amplifier output was made adjustable. | |||
The manual says this (field-installable) modification is "required for proper operation of plug-ins with numbers above | |||
[[81|Type 81]]". | |||
===Power Supply=== | ===Power Supply=== | ||