"mike" wrote in message
news:%9wNi.207$Cd7.2@trnddc03...
robb wrote:
there is quite a variety of sig/func generators on the bay
....
just wondering if there is a basic series or brand to looking
for
to test/setup a tek 2236 scope ?
thanks
rob

You need to be a lot more descriptive about what you're trying
to
accomplish.
If you have other uses for the generator, use those criteria
for your
decision. If ALL you want is to calibrate the scope, forget
it.


I know just enough to realize that best option for calibration
is... send it to a lab.

however, i want to be able to test my scope's range of
functioning initially and (on occasion) then use the generator
to inject signals into circuits that i might be hobbying with
later (or any other usefullness)


For calibration purposes, a generator won't do you any good
unless it
has the waveform precision you need and also has traceable
calibration. You can't afford that.

It's a binary situation. If you use your scope in business,
and
maintain any certifications, you must send it in to have it
done right.


just **hobby** use....
it would be a short lived, fault ridden business buying a abused
scopes from the bay and trying to start some electronics related
business with that equip.

these were purchased on hobby budget and will be used as hobby
tools.

i would just like the peace of mind (on hobbyist budget) that
the scope is not dead or way off on certain settings....
so , my thinking is to run scope through a range and
combination of measurements to know if it gives the expected
behavior (read, some close or near expected measurement/wave/func
form )


For hobby use, my experience says that a TEK scope either works
"close
enough" or it needs fixed. A scope is a poor tool for making
measurements. It's great for "looking at the waveform", but
unless
you have a scope with built-in counter and DVM, you won't get
accurate
measurements.


The tek 2236 does have a built in autoranging DMM (w/frequency,
period, width, 0-2G-Ohm meas, etc ) that can be used through a
"separate" leads port or will display the measurements from
channel 1 concurrently with CRT plus more stuff


Here's how you check a scope.
If it's a CRT scope, there are some things that mess up
everything.
Wrong high voltage can shrink or expand the display. A sure
sign
is if the display changes size when you change intensity. Make
sure
that's not a problem before you go tweeking stuff. Ditto for
other power supplies, but the effects can be much less
dramatic.


my scope passes this test but i read "online researching" that
the tek 2236 has virtually NO power supply isolation and the
measurements get munged by it's own noisey power supply ???
anyone know about this

i have seen where there appears to be slight noise (small fuzzy
waves and pulsing) in the sweeps and was wondering if this was
the isolated power supply issue or another fault in the scope ?


Do all the functions work? check.
Does it trigger? check.
Use a T-connector to put your DVM and a variable power supply
into the
vertical input. Compare deflection against your DVM. Check
Stick a transformer from the AC line into the input. Wall wart
etc.
Does it look like 60 Hz. or 50Hz. depeding on where you live.
You can check several sweep ranges.
Find a known signal source. Crystal oscillator in your
computer,
27MHz CB walkie talkie etc. Use that to check the faster
sweeps.


great, thanks for that, i will try those reccomendations ....


Now comes the hard part.
In a perfect world, frequency response and transient response
are
equivalent. In the real world, where you're looking at
tranisents,
I prefer to optimize transient response.
Stick the calibrator output into your vertical input.
(I'm assuming the scope has one. If not, skip the step.
Most generators are worse than the scope.)
If the corners are mostly square, you're done.


the built-in scope probe calibrator is what i used for first
trace test and probe calibration ( 500 mv P-P 1 kHz )

FWIW the probe calibration gave picture perfect CRT image of over
and under shoot wave form when turning the calibration screw on
probe. that is leading edge of square wave turned up or down
while rest of wave remained flat and steady ???

when adjusted the form was square, even width and flat across the
CRT.


Don't open the case if you don't have the manual with
calibration
procedures and the equipment specified.

learned that lesson a while ago

thanks mike for taking time to help an amateur hobbyist, thanks
for info and ideas

robb