Scope Calibration

[James Douglas]

Finally got the manual for my Protek 6502 scope and started working with
it. Testing it's ability to "read correctly" Started by using home built
signal generator with 455k signal, from my DMM I can measure freq but
with the scope it was like 55k off of the desired freq?

Using this scope to measure freq should it be exact? Should I have it
calibrated? Should I purchase the service manual and calibrate it myself
or leave it to professionals? Finally and recommendations for a shop
that calibrates scopes.

Thanks!

 

[Jim Yanik]

James Douglas <james.douglas@genesis-software.com> wrote in
news:_vWdnRgW6cgQHnHeRVn-og@comcast.com:

Finally got the manual for my Protek 6502 scope and started working with
it. Testing it's ability to "read correctly" Started by using home built
signal generator with 455k signal, from my DMM I can measure freq but
with the scope it was like 55k off of the desired freq?

Using this scope to measure freq should it be exact? Should I have it
calibrated? Should I purchase the service manual and calibrate it myself
or leave it to professionals? Finally and recommendations for a shop
that calibrates scopes.

Thanks!

You have to look at your instrument specifications carefully,both for the
scope and the signal generator.


Any frequency measurment method will have it's tolerances based on how the
measurement is made,component accuracies,etc.
Measuing freq. by scope is not a very accurate method;scope timebases are
usually accurate to between 1.5-3% across the center 8 divisions,3% being
the norm.
CRT linearity will also affect accuracy of a scope measurement.


TEK 2445/65 series had a counter/timer option that was reasonably accurate
(compared to a true freq.counter)because it used a crystal reference
oscillator.

Also,your signal generator's freq.accuracy and stability is dependent on
how the signal is generated.

--
Jim Yanik
jyanik
at
kua.net