[time-nuts] Question re 1pps output on the Z3805A

[Hal Murray]

mspencer12345 at yahoo.ca said:
> Does any one know the specified output level for the 1pps signals or have a
> high confidence measurement of the output voltage that they could share with
> me ?  (Measuring fast rise time signals is not really my forte and I don't
> trust my measurements of an apparent .15 volt pulse.) 

My guess would be close to 5V.  That's convenient to work with and it's what 
you get from old digital chips using TTL era switching levels.  They used 5V 
power supplies.  You may only get 4V if they used a non-CMOS chip.

That's assuming you are not using a 50 ohm terminator.


How did you measure 0.15 volts?

The pulse is probably about 10 microseconds wide.  If you have a scope, you 
can probably see it, even with an old analog scope.  You may not be able to 
measure the rise time, but you can see the pulse width.

The trick is to set things up for triggered sweep and then adjust the trigger 
level until it triggers.  Use the triggered light rather than looking at the 
picture.  Set the sweep speed to 1/10 second for the whole screen (10 ms per 
div) so it's ready again for the next pulse.  Take your time.  You have to 
wait a whole second to see if your adjustment worked.

You can use the beam as a triggered-light. Adjust the vertical offset and 
brightness so you can see the beam.  (Switch to auto triggering if you need 
to find the beam.)

After you get it triggering, you can adjust the sweep speed and brightness to 
show you the pulse.  It may help to dim the room lights.  You won't be able 
to look at the picture, only catch a glimpse of it.  But if you look at the 
area of interest, you can "see" that area when the next pulse goes off.


-- 
These are my opinions.  I hate spam.