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{{Instrument Sidebar | |||
The '''Tektronix Type 181''' is a time mark generator [[introduced in 1955]]. There is a benchtop version, | |manufacturer=Tektronix | ||
the 181, and a rackmount version, the RM181. MOD 110 substitutes a oven- | |model=181 | ||
|class=Pulse Generator | |||
thereby achieving 2 parts per million | |series= | ||
frequency stability in a 24 hour period, the same stability as the [[180A]]. | |summary=Time mark generator | ||
|image=181_PC_ISO.jpg | |||
|caption=181, early version | |||
|introduced=1955 | |||
|discontinued=(?) | |||
|designers= | |||
|manuals= | |||
* [[Media:070-292.pdf|Tektronix 181 Manual]] (sn 6917, color schematics, PDF) | |||
* [https://w140.com/mmm/tek-181.pdf Tektronix 181 Manual (PDF)] | |||
}} | |||
The '''Tektronix Type 181''' is a time mark generator [[introduced in 1955]]. There is a benchtop version, the 181, and a rackmount version, the RM181. | |||
MOD 110 substitutes a oven-stabilized1 MHz crystal oscillator (OCXO), the CO181 (Tek part number [[158-007]]), thereby achieving 2 parts per million frequency stability in a 24 hour period, the same stability as the [[180A]]. | |||
A 181 with the OCXO mod is a "181 S1". | A 181 with the OCXO mod is a "181 S1". | ||
==Internals == | ==Internals == | ||
Internally, the 181 is similar to the [[180A|180]]. | Internally, the 181 is similar to the [[180A|180]]. | ||
The oscillator drives a chain of synchronized monostable multivibrators. | The oscillator drives a chain of synchronized monostable multivibrators. | ||
Each multivibrator is triggered by the output of the previous stage, and | Each multivibrator is triggered by the output of the previous stage, and cannot be triggered again for the duration of its pulse width. | ||
cannot be triggered again for the duration of its pulse width. In the 181, | In the 181, the pulse width ratio of one stage to the next is 1:10, i.e. when a stage triggers on a pulse at its input, it propagates that event to its output, but inhibits the next nine pulses (by time, not by counting). | ||
the pulse width ratio of one stage to the next is 1:10, i.e. when a stage triggers | |||
on a pulse at its input, it propagates that event to its output, but inhibits the next | |||
nine pulses (by time, not by counting). | |||
The 181 also provides a 10 MHz output. This is generated by a 10 MHz resonator that | The 181 also provides a 10 MHz output. This is generated by a 10 MHz resonator that is driven by an amplified and waveshaped copy of the 1 MHz crystal oscillator output. | ||
is driven by an amplified and waveshaped copy of the 1 MHz crystal oscillator output. | Since it is a harmonic, the 10 MHz output has same relative frequency accuracy as the reference oscillator. | ||
Since it is a harmonic, the 10 MHz output has same relative frequency accuracy as | |||
the reference oscillator. | |||
The power supply of the 181 produces +300 V and −150 V regulated voltages and | The power supply of the 181 produces +300 V and −150 V regulated voltages and +400 V, −8 V, and −25 V unregulated. | ||
+400 V, −8 V, and −25 V unregulated. The voltage reference is a [[5651]] tube. | The voltage reference is a [[5651]] tube. The output tubes for both regulators are [[12B4]] and the feedback amplifier tubes are [[6AU6]]. | ||
The output tubes for both regulators are [[12B4]] and the feedback amplifier | The 181 does not contain a fan or a [[thermal cutoff]]. | ||
tubes are [[6AU6]]. The 181 does not contain a fan or a [[thermal cutoff]]. | |||
==Pictures == | ==Pictures == |