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.

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.

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.

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.

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.

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.

Don't open the case if you don't have the manual with calibration
procedures and the equipment specified. You can substitute
equipment, but your question suggests you don't have the knowledge
to do that. Virtually any non calibration generator you pick
will be worse than your scope. Just getting the waveform into
the scope without degrading it is an art.

RESIST TEMPTATION TO MAKE IT PERFECT.
YOU RISK MAKING IT MUCH WORSE.
RESIST TEMPTATION TO LET YOUR BUDDIES TALK YOU
INTO MAKING IT PERFECT.
IF IT AIN'T BROKE, DON'T FIX IT.
IT WILL NEVER BE PERFECT, DON'T EVEN TRY.
If it's far enough out of calibration to need significant tweeking
it's probably broke. Fix it before you try to calibrate it.
Leave the covers on and enjoy your scope.

The above assumes the scope works and nobody's been inside
messing with adjustments.

Scopes are great for looking at waveforms. If you need to
know the frequency of something, use a counter. If you need
to know the voltage of something, use a DVM.

mike
designed scope calibration generators in a former life.

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