[time-nuts] Digital Scopes - suggestions

Didier Juges didier at cox.net
Wed Oct 24 21:53:34 EDT 2007

I did some more experiments with the Tek TDS-210.

When measuring the PPS signal from the Thunderbolt, I can offset the trigger
point in a calibrated fashion to the left of the screen up to the 250uS/div
sweep speed. That means at that point, the actual trigger point is 400
screen widhts to the left of the scope :-) When I put the next pulse right
in the middle of the screen, the offset is displayed as exactly 1.000
second. If I move the pulse by exactly 7 pixels to the right of the center
of the screen, the offset changes from 1.000 to 999.9 milli-second. That's
good resolution for a scope.

I bought my TDS-210 used but in like new condition with the Tek carry case,
manual and probes in original condition for $400 3 years ago. I highly
recommend it. The TDS-220 is the same scope with a rating of 100 MHz instead
of 60 MHz. Both have very high ADC conversion rate listed as 1 GS/sec, so
even a single shot sampled at the highest sweep speed looks considerably
smoother than the same shot on my Tek 2430A DSO. These have the monochrome
LCD, which I actually prefer to the color LCD used on the newer scopes,
because it appears much sharper, and the traces are not offset, so signals
that are really the same actually superpose each other.

Newer scopes have more desirable features, such as USB connector for
computer connectivity and for a thumb drive, and a color screen, but they
also cost a lot more.

Didier KO4BB

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