585: Difference between revisions

The 58x series were the first Tek scopes with [[distributed deflection plates]], the first Tek scopes to use a cross-wound continuous delay line, and the last with a [[distributed amplifier]].

 

At 100 MHz (down-rated to 95 MHz in 1962 and 85 MHz for the 585A in 1963) with the [[80|Type 80 plug-in]] and up to 85 MHz with the dual-channel [[82|Type 82]], they were the highest-speed general purpose scopes of Tek's tube scope era. (The 1 GHz [[519]] was specialized with no vertical amplifier.)

but are electrically different. The main difference is the impedance of the signal that passes

Schmitt trigger circuit was replaced by an [[STD615]] 10 mA [[tunnel diodes|tunnel diode]] AC-coupled to the base-emitter junction of an [[OC171]] germanium PNP transistor as a pulse amplifier.   

Like the [[545]], [[551]], and [[555]], the 585 uses two [[distributed amplifier]]s in the vertical signal path, one with seven differential [[6DJ8]] stages driving a helically-wound, differential [[delay line]], followed by a five-stage differential distributed driver amplifier and a [[7699]] or [[6939]] 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 fast rise time and high sensitivity (~5 V/cm vertically), albeit at the cost of limiting vertical deflection to slightly over 4 cm. Total acceleration voltage is 10 kV.

The manual says this (field-installable) modification (040-275) is "required for proper operation of plug-ins with numbers above [[81|Type 81]]". Non-A instruments with this termination have a front panel label reading "standardized vertical".

The 585 power supply is similar to other Tek scopes of the era such as the [[549]].  A linear regulator with a [[5651]] reference tube, a [[12AX7]]/[[6AU6]] error amplifier and three parallel [[12B4]] series pass tubes produces −150 V.   

This is the only adjustable rail, all other regulated voltages are referenced to it.   

The +100 V and +350 V regulators use half a [[6080]] each as the pass element, the +225 V two.   

In the +500 V path, a [[12B4]] performs this function.   

The unregulated +325 V input to the 225 V regulator is used to supply the HV oscillator, a [[6AU5]].

The 585 uses semiconductor diodes as rectifiers and germanium transistors in the 12.6 V power supply, and except for unmodified instruments before SN 1070, a tunnel diode and another germanium transistor in the time base A trigger circuit.