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frequency stability in a 24 hour period, the same stability as the [[180A]]. | frequency stability in a 24 hour period, the same stability as the [[180A]]. | ||
* [http:// | Internally, the 181 is similar to the [[180A|180]]. | ||
The oscillator drives a chain of synchronized monostable multivibrators. | |||
Each multivibrator is triggered by the output of the previous stage, and | |||
cannot be triggered again for the duration of its pulse width. In the 181, | |||
these pulse width ratio of one stage to the next is 1:10. | |||
The result is that when a stage triggers on a pulse at its input, it propagates | |||
that event to its output, but inhibits the next nine pulses. It does this by time, | |||
not by counting. After a stage returns to its resting state, it is triggerable again. | |||
So it triggers once every ten input pulses. | |||
The 181 also provides a 10MHz output. This is generated a 10MHz resonator that | |||
is driven by an amplified and waveshaped copy of the 1MHz crystal oscillator output. | |||
Since it is a harmonic, the 10MHz output has same frequency percentage accuracy is | |||
the reference oscillator. | |||
The power supply of the 181 produces +300V and -150V regulated voltages and | |||
+400V, -8V, and -25V unregulated. The voltage reference is a [[5651]] tube. | |||
The output tubes for both regulators are [[12B4]] and the feedback amplifier | |||
tubes are [[6AU6]]. The 181 does not contain a fan or a [[thermal cutoff]]. | |||
* [http://w140.com/mmm/tek-181.pdf Tektronix 181 Manual (PDF)] | |||
<gallery> | <gallery> |