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The Tektronix Type A is a single-channel preamp [[introduced in 1959]] for [[500-series scopes]]. | The Tektronix Type A is a single-channel preamp [[introduced in 1959]] for [[500-series scopes]]. | ||
A [[545]] with a Type A has a system risetime of 18 nanoseconds. The plug-in uses a [[12AU6]] | A [[545]] with a Type A has a system risetime of 18 nanoseconds and a bandwidth of 20MHz. The plug-in uses a [[12AU6]] | ||
in the front end as a cathode follower. This input stage drives the second stage, a | in the front end as a cathode follower. This input stage drives the second stage, a | ||
differential amplifier made of two 12AU6 tubes. The second stage drives the output stage, | differential amplifier made of two more 12AU6 tubes. The second stage drives the output stage, | ||
a pair of cathode followers made of both halves of | a pair of cathode followers made of both halves of a [[12AT7]] tube. The plate of each output tube | ||
is connected to the cathode of the other output tube by a 0.005 microfarad capacitor. This | is connected to the cathode of the other output tube by a 0.005 microfarad capacitor. This | ||
"cross-coupling" extends the high-frequency response. | |||
Although 1959 was the first year one could find a "Type A" in the catalog, the same | |||
instrument with earlier "Type 53/54A" nomenclature was in the August 1956 | |||
Short Form catalog, and its slower Type 53A ancestor was in the August 1954 | |||
catalog which introduced the first 500-series scopes, the [[531]] and the [[535]]. | |||
Type 53A has only three tubes, and a bandwidth of 10MHz in the 530 mainframes. | |||
Tek never documented its performance in the 540 mainframes. | |||
* http://bama.edebris.com/manuals/tek/a/ | * http://bama.edebris.com/manuals/tek/a/ | ||
* http://w140.com/tek_fcp/tek_type_a_factory_cal_proc.pdf | * http://w140.com/tek_fcp/tek_type_a_factory_cal_proc.pdf | ||
Revision as of 12:50, 17 September 2010
The Tektronix Type A is a single-channel preamp introduced in 1959 for 500-series scopes. A 545 with a Type A has a system risetime of 18 nanoseconds and a bandwidth of 20MHz. The plug-in uses a 12AU6 in the front end as a cathode follower. This input stage drives the second stage, a differential amplifier made of two more 12AU6 tubes. The second stage drives the output stage, a pair of cathode followers made of both halves of a 12AT7 tube. The plate of each output tube is connected to the cathode of the other output tube by a 0.005 microfarad capacitor. This "cross-coupling" extends the high-frequency response.
Although 1959 was the first year one could find a "Type A" in the catalog, the same instrument with earlier "Type 53/54A" nomenclature was in the August 1956 Short Form catalog, and its slower Type 53A ancestor was in the August 1954 catalog which introduced the first 500-series scopes, the 531 and the 535. Type 53A has only three tubes, and a bandwidth of 10MHz in the 530 mainframes. Tek never documented its performance in the 540 mainframes.