Re: Tek 2465B Calibrator issues

Tom Gardner
 

I'm unconvinced it could check the measurement accuracy in one sense, since I assume the cursors and calibration signal are derived from the same source.

It could be used to check the X linearity and the X magnification, but personally I'd just use other independent equipment for that.

On 28/03/19 01:18, Siggi wrote:
The point of this on the 2465s is that it allows the user to validate the
time base accuracy on the spot. For this purpose, the poor rise and fall of
the calibrator are unimportant, as you just line some part of the rise or
fall up to the graticule for a check.

It sure looks ugly at fast sweeps though :).

On Wed, Mar 27, 2019 at 20:43 Tom Gardner <tggzzz@...> wrote:

I don't like the "calibrator" output on the 24x5 series: the period
changes
according to the timebase so that there is always 5 cycles on the display.
At
high sweep speeds (i.e. much faster than1ms/div) the poor risetime of the
calibrator signal is evident.

The only practical use for a calibrator output is to calibrate the low
frequency
frequency response of a *10 "high" impedance probe. For that, all you need
is a
couple of cycles of a 1kHz waveform with a flat top - and you just tweak
the
scope probe so that its response looks flat. There are many descriptions
of how
to do that.

Summary: if you have fast sweep speeds (say <1us/div) and the waveform is
distorted, don't worry because that is normal. If, OTOH, the waveform is
distorted at 200us/div, then tweak the probe. If a problem remains, post a
picture.


On 26/03/19 13:29, Marcial Gomez Varas wrote:
Hi everyone,

I bought some time ago (2017) a TEK 2465B that I didn't have too much
time to play with (having 2 kids and a travelling job doesn't help!)
I have been toying with it lately, and I've discovered that the
calibrator is showing some really awful square signal.
It's clearly NOT square ! It has quite a bit of slope in the rise and
fall lines, and bouncing on the high level.
I have checked and both the output levels and frequency seem to be OK,
but somehow the signal is distorted.
Could it be some capacitor? Looking at the service manual it shows to be
in the A1 board, section 5 (That should be in the middle left side, am I
right?)
Any help would be appreciated !

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