o-scope - test-drb@ccmp.vtda.org

6 May 2001

From: Jim Strickland &lt;jim(a)calico.litterbox.com&gt;
...
 So I'm a 'scope newbie, does the probe
impedance (13 pf) have to match the
rating on the jack on the scope (47 pf) for the waves coming out of the 
calibration jack to be properly square?  And if so, does anyone have a source
for probes that work with ancient scopes like this?
 Most probes can be adjusted to work with a range of capacitance, they 
normally have a little adjustment hole at the end that attaches to the
scope.  Adjust it for the flattest trace.

...
 Also, how do I tell a 535a from a 545a?  
 Look above the CRT and see if it says TYPE 535 or TYPE 545?  I assume
this is a big old tube scope, if not ignore the rest.  
...
 From Oscilloscopes, Selecting and Restoring a Classic
by Stan Griffiths the 535A is 15MHz bandpass 5MHz trigger.  545A 33 MHz bandpass 5
MHz trigger.
Bandpass may be less depending on what plugin is installed.

I have a 547 (50 MHz bandpass and trigger) which I use to maintain my 
PDP-8's.  Mine is a nice scopes but can be a little temperamental.  
Depending on what you are using it for the limited bandwidth (especially
trigger) may be an issue.

David Gesswein
http://www.pdp8.net/  -- Run an old computer with blinkenlights