[Test-Equipment] scope delta cursor adjustment

[Al Parker]

hI Dick,
    I don't know abaout the "delta adjustment", but your DMM is measuring 
1.027 RMS voltage, and it may not be too accurate at 1kc.  Your seeing 3.24v 
peak to peak on the scope.  3.24 p-p = 1.14 RMS, so it looks to me like your 
only off 0.113 volts, and maybe that's within the margin of error for your 
setup.  I think you should expand the trace vertically to fill as much of 
the screen as possible, to insure minimum error.
73,
Al, W8UT

----- Original Message ----- 
From: "Dick KF4NS" <kf4nsradio at verizon.net>
To: "Test Equipment" <test-equipment at mailman.qth.net>
Sent: Monday, July 13, 2009 2:02 PM
Subject: [Test-Equipment] scope delta cursor adjustment


>I have a TEK 2465 and was making some test comparisons with my
> multi-featured DMM. I had never really done this before so had never
> paid any attention to the delta cursor positioning.
>
> Before I dig into the service manual for adjustment procedure I better
> pick some brains better than mine.
>
> I found that I had been setting the cursor at the very peak of the
> trace and the result was a higher voltage reading of the 1khz sine
> wave than should be. Example: for a DMM reading of 1.027V RMS
> I get 3.24V P-P on the scope. If I overlap the cursor and the peak I
> get the comparable reading. I realize that this delta feature is not
> a precision test for voltage. I used both the X10 probe and a quality
> section of 50 ohm coax. I used both 1Mohm GND and 50ohm DC input
> coupling. Result is always the same.
>
> I also realize that the cursor is not a perfect flat, straight line so
> maybe
> I am making a mountain out of a mole hole. After all, the reading is
> only 0.34V too high. If I use the recommended 5 divisions on the
> display it is better but I normally do not expand the trace that much.
>
> Opinions please.
>
> 73, Dick KF4NS
> St Petersburg, FL 33714 USA
> Keep The Glow!
>
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