Weird (??) display in Tek 2465BCT CAL01 procedure

Rogerio O

Dear All,

After fixing the A5 board of the scope which was damaged due to capacitor leakage I have started to try to calibrate the scope.

I managed to adjust DAC REF without any issues and moved to CAL01.

After trying to read as much as I could about the automated cal steps, I managed to find a very good post from Randy Peckenpaugh, wb0smx at his website which documented all the calibration steps of a 2465A WITH PHOTOS!
See (;paged=3).
I am using a TG501 with a 50 ohm termination (just to make sure I do not overload the scope input) as the "signal source" with a coax Tee attached to the output.
One side of the tee is connected to the 2465 using a TEK 012-0482-00 precision coax cable and the other side is connected to my TDS2024B that is used to "monitor" the signal used for calibration.
The 50 ohm termination and the signal monitoring scope are just precautions since the TG501 is rarely used and it may go crazy during the calibration procedure.

I could follow the procedure without problems until I reached step n.
The 2465BCT display is very different from the pictures, and the display is not "stable" as it was on the previous steps.
Also, I could not obtain a well defined pulse at the Delayed B sweep trace as I could see in the picture of the above-mentioned reference.
What I see one near horizontal line and one curved that shift when I move the DELTA knob.
I have started a new picture album with a movie and some photos of what I am getting as well as the behaviour shown in the reference.

Any help will be welcome.

Rogerio O

I forgot to mention that the album is named "Tek 2465BCT CAL01 weird behavior."



the 2465x calibration is a bit weird in terms of how it is described, I agree ;-)

But, you have to do the calibration exactly as described, you cannot add a 50 Ohm terminator if not told to do so.
The calibration routine inside the scope will engage its own 50ohm when needed, and you cannot have two in parallel at some points.