585: Difference between revisions

585 (view source)

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 The main difference is the impedance of the signal that passes
 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,
-Indeed, in those scopes, the plug-in is directly driving tube grids in the mainframe.
+driving tube grids in the mainframe.
-In 580-series scopes, the plug-in expects the mainframe to have a controlled impedance of 93 Ω per side (differential signal).
+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 pin-out being essentially flipped 180° from its
+the 580-series pin-out being essentially flipped 180° from its 530/540/550 series counterparts
-/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.
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 made of a pair of miniature dual triode tubes.
-Starting at serial number 1071, the miniature dual triode Schmitt trigger was replaced by a
+Starting at serial number 1071 (and sometimes retrofitted to earlier instruments), the dual-triode
- mA [[tunnel diodes|tunnel diode]] and a pulse amplifier made with an [[OC171]] Germanium PNP
+Schmitt trigger circuit was replaced by a 10 mA [[tunnel diodes|tunnel diode]] AC-coupled to the
-transistor.  The tunnel diode is AC-coupled to the base-emitter junction of the transistor.
+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 ===
-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]],
-the [[T581]], enabling it to have both high sensitivity and fast risetime.  Total acceleration voltage is 10 kV.
+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.
 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===