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The 585A uses a tunnel-diode trigger circuit (see below), adds HF Sync and AC LF reject modes to the timebase A trigger selector, and adds a [[trace rotation]] coil. | The 585A uses a tunnel-diode trigger circuit (see below), adds HF Sync and AC LF reject modes to the timebase A trigger selector, and adds a [[trace rotation]] coil. | ||
==Links== | |||
* [https://www.radiomuseum.org/r/tektronix_crt_oscilloscope_585.html Tek 585] @ radiomuseum.org | |||
* [https://youtube.com/watch?v=RvemavylsCI Inside a Tek 585A] @ YouTube | |||
==Internals== | ==Internals== | ||
=== Plug-in Interface === | === Plug-in Interface === | ||
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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 (~5 V/cm vertically) | 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. | |||
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. | ||
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After serial number 2585, the back termination of the final distributed amplifier output was made adjustable. | After serial number 2585, the back termination of the final distributed amplifier output was made adjustable. | ||
The manual says this (field-installable) modification (040-275) is "required for proper operation of plug-ins | The manual says this (field-installable) modification (040-275) is "required for proper operation of plug-ins | ||
with numbers above [[81|Type 81]]". | with numbers above [[81|Type 81]]". Instruments with this termination have a front panel label reading | ||
"standardized vertical". | |||
===Power Supply=== | ===Power Supply=== | ||
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 | 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]]. | |||
A transistor-based regulator supplies a +12.6 V heater voltage to the plug-in. | A transistor-based regulator supplies a +12.6 V heater voltage to the plug-in. | ||
A [[delay relay|6N045 delay relay]] controls a multi-contact relay to switch supply voltages on only after the tubes are warmed up. When the main relay engages, the delay relay is cut out so it will be ready to delay again even after a quick interrupt in power input. | A [[delay relay|6N045 delay relay]] controls a multi-contact relay to switch supply voltages on only after the tubes are warmed up. | ||
When the main relay engages, the delay relay is cut out so it will be ready to delay again even after a quick interrupt in power input. | |||
The 585 contains a 53°C (128°F) [[thermal cutoff]]. | The 585 contains a 53°C (128°F) [[thermal cutoff]]. | ||
===Semiconductors=== | ===Semiconductors=== | ||
The 585 uses semiconductor diodes as rectifiers and | The 585 uses semiconductor diodes as rectifiers and germanium transistors in the 12 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. | |||
=== Rackmount Versions === | === Rackmount Versions === |