82

The Tektronix Type 82 is a dual-trace plug-in for the 580-series scopes. The Type 82 combined with a 585 or 585A provides a 4 nanosecond risetime.

Key Specifications

Rise time	4 ns (in 585 mainframe), i.e. 85 MHz bandwidth
Deflection	10 mV/Div to 50 V/Div, 1-2-5

Internals

The front end of the Type 82 is a 7586 nuvistor cathode-follower, followed by bipolar diff-amps and diode channel switching, followed by a distributed output amplifier made of three 6DJ8 tubes, with differential 93-ohm outputs.

The use of a distributed amplifier in a plug-in is unusual. Note that the 58x series differs from 500-series scopes mainly in that the vertical signal interface between the plug-in and the mainframe is a low controlled impedance (93 ohms), as opposed to other 500-series scopes that present a high impedance to the plug-in.

Stan Griffiths wrote:

If you feed [a fast risetime] signal into an early type 82, you will find that the top three least sensitive positions have really terrible frequency response ... so bad, in fact, that some customers thought they were broken. When told this was normal, these customers wondered why Tek ever included them on the plugin. The answer was that they were still useful for low frequency signals ... but Tek never really made it well known that these 82 attenuator positions were lousey. I think this was fixed on the later 82's as Tek learned how to make better attenuators. If you have an early 82 and need to look at high frequency signals on the less sensitive ranges, the answer is to get X100 probes and use them on the more sensitive ranges where the frequency response is better.

The P6008 voltage probe was designed for use with the Type 82.

Pictures

• 

  Front view, early style

• 

  Left view.

• 

  Top view.

• 

  Right view

• 
• 
• 
• 
• 

  Bottom of distributed amplifier

• 

  Top of distributed amplifier

• 

  Front view, later style