S
steve
The scope is a Tektronix 2465a, I don't have the S/N offhand, but I
can get it tomorrow if needed. It's a newer unit, with all
pushbuttons instead of toggle switches.
The problem is that when in delayed sweep, measuring delta t using
overlap gives wrong readings (i.e. overlapping two marks from a time
mark generator at 50us reads 52.5us), but using the cursors, still in
delayed sweep, it reads on (i.e. putting cursors on rising edges of
two pusles). The horizontal axis also is correct, and the cursors are
correct again. So, the only problem is when in B swp, overlapping two
pulses to get a reading gives wrong numbers. Using cursors in A or B
swp gives proper readings,
We tried going through cal 01, 02, 03, and 04 with no luck. The offset
error is uniform for all B swp times for each A swp time (i.e. for
A=200us, the error will be the same for all B times, appx 10.2us, for
A=50us, the error will be the same for all B times, appx 2.5us).
Sorry if this is confusing, I will gladly clear anything up if I can.
Any help would be greatly appreciated, we're just a small calibration
lab, family run, and right now our only other standard scope (another
2465), is waiting on pots from sphere.co.
On a different note, the other 2465 we have had a problem with the
display. After warming up for probably half an hour, some dots appear
on the screen. They are on vertical graticule lines, and turning the
trace and readout intenities down doesn't change them. I've freeze
sprayed all I.C.'s with no effect. We aren't as concerned with this
problem, because the all time readings on this scope are dead on, and
we just need a NIST traceable reference so we can keep calibrating.
Thanks for any help you can give, and if I can clear anything up just
let me know.
Steve Kamego,
Calibration Specialty Inc.
can get it tomorrow if needed. It's a newer unit, with all
pushbuttons instead of toggle switches.
The problem is that when in delayed sweep, measuring delta t using
overlap gives wrong readings (i.e. overlapping two marks from a time
mark generator at 50us reads 52.5us), but using the cursors, still in
delayed sweep, it reads on (i.e. putting cursors on rising edges of
two pusles). The horizontal axis also is correct, and the cursors are
correct again. So, the only problem is when in B swp, overlapping two
pulses to get a reading gives wrong numbers. Using cursors in A or B
swp gives proper readings,
We tried going through cal 01, 02, 03, and 04 with no luck. The offset
error is uniform for all B swp times for each A swp time (i.e. for
A=200us, the error will be the same for all B times, appx 10.2us, for
A=50us, the error will be the same for all B times, appx 2.5us).
Sorry if this is confusing, I will gladly clear anything up if I can.
Any help would be greatly appreciated, we're just a small calibration
lab, family run, and right now our only other standard scope (another
2465), is waiting on pots from sphere.co.
On a different note, the other 2465 we have had a problem with the
display. After warming up for probably half an hour, some dots appear
on the screen. They are on vertical graticule lines, and turning the
trace and readout intenities down doesn't change them. I've freeze
sprayed all I.C.'s with no effect. We aren't as concerned with this
problem, because the all time readings on this scope are dead on, and
we just need a NIST traceable reference so we can keep calibrating.
Thanks for any help you can give, and if I can clear anything up just
let me know.
Steve Kamego,
Calibration Specialty Inc.