Tektronix 7854 O'scope plugin concept

[tkamiya]

Hi,

I have a new-to-me Tektronix 7854 scope.  As pretty much everybody knows, these will take just about any 7000 series plugins for verticals and horizontal time-base.  There are 4 plugin slots on this model.

I can understand why someone may want two or more vertical plugins.  But why more than one time-base?  Currently, I have 7B85 delaying time-base.  Why would I want something else?  (I know this one does not do x-y)  Also, the mainframe distinguishes slot A as delaying time base (only?).  What's so special about delaying?  (I know what it means) 

I am pretty sure there IS a good reason for each of these features.  I just would like to know what they are....

[David Hess]

Two separate timebase slots is feature in the 4-bay Tektronix 7000 series mainframes.

If you combined a delaying timebase in the left horizontal slot (7B85 or 7B15) and and delayed (or delaying) timebase in the right horizontal slot (7B50A, 7B80, 7B85, 7B10, 7B15, 7B92A, or 7B87), then you gain the features of a dual delaying timebase which can be used to "magnify" a trace horizontally and make better measurements in time.

Or two separate timebases can be used to display the same signal at two different sweep speeds.  Or different signals can be display at different sweep speeds.  This is like having two oscilloscopes with the same display.  If two dual delaying timebases like the 7B53A or 7B92A are installed, then it is like having two separate dual delaying timebase oscilloscopes with the same display.

The extra timebase slot is also convenient for plug-ins like digital multimeters and timer/counters.  This slot has access to the internal trigger signal path so timing measurements can be directly made on the displayed signal.

A spectrum analyser can be installed into the center two slots to display time and frequency at the same time like with a modern mixed domain oscilloscope.

In the case of the 7854, the 7B87 delayed timebase allows single shot digital storage and pretrigger storage.  Usually this would be combined with a 7B85 delaying timebase in the left slot for full dual delayed timebase operation when using these storage modes.