What is a "mainframe" oscilloscope or logic analyzer?

All,

I've seen several oscilloscopes and logic analyzers advertized as
"mainframes". I understand that these devices need specialized plug-in
cards to operate, but is there anything else I need to know about them?
Are they typically configured through the front panel, just like their
"stand alone" cousins?

-Chess

 

[Jim Yanik]

chessaurus@yahoo.com wrote in
news:1152374457.632448.225030@m73g2000cwd.googlegroups.com:

All,

I've seen several oscilloscopes and logic analyzers advertized as
"mainframes". I understand that these devices need specialized plug-in
cards to operate, but is there anything else I need to know about them?

Yes,lots. ;-)

Are they typically configured through the front panel, just like their
"stand alone" cousins?

-Chess

A mainframe oscilloscope(MF) has the power supply,HV,display and CRT driver
amplifiers.Some may be CRT-storage displays that retain the waveform for
closer examination.(after the event's passed or you remove the probe.)

The plug-ins(PIs) contain the vertical amplifiers,attenuators,others have
the timebase or horizontal amplifiers.
Then there are specialized PIs like the TEK 7CT1N curve tracer,spectrum
analyzer PIs that take up more than one compartment(slot),sampling PIs that
extend the bandwidth far above the real-time BW,digital PIs that can make
the MF a digital storage scope,or a logic analyzer,or a word
recognizer/signature analyzer.
There are differential vertical amp PIs(7A13,7A22),FET probe PIs,50 ohm
input PIs,75ohm input PIs for cable uses) Different PIs have differing
BW,also dependent on MF bandwidth.Some instruments may have on screen
readouts of parameters.


This wide selection makes the mainframe a versatile test instrument.
(too bad TEK doesn't make them anymore)

The MF has the basic display controls,and the PIs have the vert and horiz
position,gain(volts/div),sweep speed(time/div),or other specific controls
on their front panels.
The TEK 11000(11K) series is fully programmable thru a GPIB interface.
(only using 11K PIs.)

The later TEK 7000 series mainframes are very good serviceable instruments.
7904,7904A,7104,7704A,7603 are all excellent MFs.

AVOID 7400,7500 series MFs,and IMO,avoid storage MFs.

An important caveat is that TEK-made ICs are no longer being
made,stocked,or sold new. Strictly salvage from "parts scopes".
TEK-made ICs have the prefix 155-xxxx-xx or 234-xxxx-xx.


--
Jim Yanik
jyanik
at
kua.net

 

A mainframe oscilloscope(MF) has the power supply,HV,display and CRT driver
amplifiers.Some may be CRT-storage displays that retain the waveform for
closer examination.(after the event's passed or you remove the probe.)
... snip ...
Jim Yanik

Jim,

I really appreciate you taking the time to explain these devices and
share your perspective on them. Sounds like the mainframe concept is a
good one. I didn't realize that Tek had discontinued making mainframe
oscilloscopes. They do appear to still make mainframe logic
analyzers... at least, I've seen quite a few modern Tek MF Logic
Analyzers on Ebay recently.

Thanks again for your help.
-Chess