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{{Instrument Sidebar | |||
|manufacturer=Tektronix | |||
|model=180 | |||
|class= | |||
|series= | |||
|summary=Time-mark generator | |||
|image=Tek 180A-Front-On.jpeg | |||
|caption=Tektronix 180A Time-mark generator | |||
|introduced=1958 | |||
|discontinued= | |||
|designers= | |||
|manuals= | |||
* [[Media:070-358.pdf|Tektronix 180A Manual]] (PDF) | |||
* [https://w140.com/tek_fcp/tek_type_180_field_recal_proc.pdf Tektronix 180 Field Recalibration Procedure (PDF)] | |||
* [https://w140.com/tek_fcp/tek_type_180a_factory_cal_proc.pdf Tektronix 180A Factory Calibration Procedure (PDF)] | |||
* [[Media:Tek 180 180a irb no ocr.pdf|Tektronix 180 and 180A Instrument Reference Book (PDF, needs OCR)]] | |||
}} | |||
The '''Tektronix 180A''' was [[introduced in 1958]] and is an all-tube time mark generator with an oven-controlled crystal oscillator (OCXO). | |||
Time mark generators put out pulses at user-selectable intervals. They are primarily used for calibrating the time-base of oscilloscopes. | |||
Switches on the front panel select which of the divided-down pulse signals will be added together to form the output waveform. | |||
Switches on the front panel select which of the divided-down pulse signals | The Tektronix 180 has toggle switches. The 180A has pushbutton switches. | ||
will be added together to form the output waveform. | |||
The signal path of the 180A starts with an OCXO producing 1 MHz, which is then divided down using synchronized monostable multivibrators. | |||
This scheme does not require precision in the time constant of the monostable multivibrators. | This scheme does not require precision in the time constant of the monostable multivibrators. | ||
The only precision component in the 180A is the OCXO (part number [[158-007]]). | The only precision component in the 180A is the OCXO (part number [[158-007]]). | ||
In addition to the time mark generator functionality, the 180A also produces | In addition to the time mark generator functionality, the 180A also produces sine waveforms at 5 MHz, 10 MHz, and 50 MHz. | ||
sine waveforms at 5 MHz, 10 MHz, and 50 MHz. | |||
These frequencies are produced by feeding the 1 MHz OCXO output to a series of three frequency multipliers. | These frequencies are produced by feeding the 1 MHz OCXO output to a series of three frequency multipliers. | ||
First the 1 MHz is quintupled to get the 5 MHz signal. | First the 1 MHz is quintupled to get the 5 MHz signal. | ||
Then the 5 MHz signal is doubled to the 10 MHz signal. | Then the 5 MHz signal is doubled to the 10 MHz signal. | ||
Then the 10 MHz signal is quintupled, yielding the 50 MHz signal. | Then the 10 MHz signal is quintupled, yielding the 50 MHz signal. | ||
Each of the three frequency multipliers is composed of a [[6DK6]] pentode | Each of the three frequency multipliers is composed of a [[6DK6]] pentode driving an LC resonator tuned to 5 MHz, 10 MHz, and 50 MHz. | ||
driving an LC resonator tuned to 5 | |||
The 180A manual suggests an interesting procedure for calibrating the OCXO, | The 180A manual suggests an interesting procedure for calibrating the OCXO, by attaching a small antenna to deliberately interfere with the national time standard broadcast, and observing the interference with a communication receiver. | ||
by attaching a small antenna to deliberately interfere with the national time standard broadcast, | |||
and observing the interference with a communication receiver. | |||
The method is to zero-beat the WWV standard frequency broadcast with the internal crystal oscillator to align the OCXO frequency. | The method is to zero-beat the WWV standard frequency broadcast with the internal crystal oscillator to align the OCXO frequency. | ||
First tune ham receiver to WWV broadcast - say | First tune ham receiver to WWV broadcast - say 10 MHz - and watch the audio subtone using an oscilloscope connected to the audio out of the receiver. | ||
Then wait for specific minutes of the hour where there is no audio subtone in WWV. | Then wait for specific minutes of the hour where there is no audio subtone in WWV. | ||
Then select | Then select 1 μs output on 180A, which will have 10 MHz as the harmonic. | ||
Connect a wire from the output of the 180A as an antenna and couple it to the antenna input of the receiver. | |||
This way, the 10 MHz WWV and 10 MHz harmonic from the 180A will beat in the receiver input, and the difference will be visible as a wave in the oscilloscope. | |||
Then adjust C105 to align the crystal frequency so close to the reference WWV 10 MHz that the frequency difference becomes zero or the waveform on the scope becomes flat. | |||
You could also use the S-Meter in the receiver instead of the oscilloscope to perform the same. | You could also use the S-Meter in the receiver instead of the oscilloscope to perform the same. | ||
The 180A, serial number 5599 and up, uses the [[120-119]] power transformer. | The 180A, serial number 5599 and up, uses the [[120-119]] power transformer. | ||
{{MissingSpecs}} | |||
==See Also== | ==See Also== | ||
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* [[Media:Tek discussion of hickok clone of 180a.pdf]] | * [[Media:Tek discussion of hickok clone of 180a.pdf]] | ||
==Pictures== | |||
== | |||
===180=== | ===180=== | ||
<gallery> | <gallery> | ||
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Tek 180a late sn power supply.png|late sn power supply | Tek 180a late sn power supply.png|late sn power supply | ||
</gallery> | </gallery> | ||
[[Category:Introduced in 1958]] | [[Category:Introduced in 1958]] |