Vpp different from signal generator and scope

[[email protected]]

I have something simple but I can't seem to find an answer to it.

I am getting a different Vpp measurement on the scope from the signal
generator. When put in a 1Vpp 200KHz square wave from my signal
generator, while the frequency is dead on at 200KHz, I got a reading
of 2 Vpp on the scope. I made sure the signal generator is outputting
Vpp, not RMS. My scope is on DC Coupling.

Does anyone know why my Vpp reading on the scope is doubled?

Many thanks.

 

[John Popelish]

I have something simple but I can't seem to find an answer to it.

I am getting a different Vpp measurement on the scope from the signal
generator. When put in a 1Vpp 200KHz square wave from my signal
generator, while the frequency is dead on at 200KHz, I got a reading
of 2 Vpp on the scope. I made sure the signal generator is outputting
Vpp, not RMS. My scope is on DC Coupling.

Does anyone know why my Vpp reading on the scope is doubled?

Are you using a divide by 10 probe?
If so, have you tuned the probe compensation capacitor to
produce a flat frequency response?

Another possibility is that your vertical gain knob has
slipped on the shaft, since the gain ranges normally have
1-2-5 volts per cm jumps.

Does your scope have a reference output to check both the
frequency response and gain?

 

[JeffM]

willwestward@ gmail.com MULTI-POSTED:

I have something simple but I can't seem to find an answer to it.

Stop being selfish.
If you are going to post the same question MULTIPLE times
http://groups.google.com/groups/sea...iqhXo4cocwWvDVg2RHsu8f1bCg&scoring=d&filter=0
use this method:
http://www.google.com/search?q=cach...arked-as-Read-in-ALL-*-groups+Newsgroups.line

 

[Michael A. Terrell]

I have something simple but I can't seem to find an answer to it.

I am getting a different Vpp measurement on the scope from the signal
generator. When put in a 1Vpp 200KHz square wave from my signal
generator, while the frequency is dead on at 200KHz, I got a reading
of 2 Vpp on the scope. I made sure the signal generator is outputting
Vpp, not RMS. My scope is on DC Coupling.

Does anyone know why my Vpp reading on the scope is doubled?

Many thanks.

It sounds like the rated output is into a fixed impedance, and you
don't have a load on the generator. You can get two or more times the
rated output when the equipment is used, this way.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[bg]

[email protected] wrote in message

I have something simple but I can't seem to find an answer to it.

I am getting a different Vpp measurement on the scope from the signal
generator. When put in a 1Vpp 200KHz square wave from my signal
generator, while the frequency is dead on at 200KHz, I got a reading
of 2 Vpp on the scope. I made sure the signal generator is outputting
Vpp, not RMS. My scope is on DC Coupling.

Does anyone know why my Vpp reading on the scope is doubled?

Many thanks.

The generator needs to be terminated.
bg

 

[Jamie]

I have something simple but I can't seem to find an answer to it.

I am getting a different Vpp measurement on the scope from the signal
generator. When put in a 1Vpp 200KHz square wave from my signal
generator, while the frequency is dead on at 200KHz, I got a reading
of 2 Vpp on the scope. I made sure the signal generator is outputting
Vpp, not RMS. My scope is on DC Coupling.

Does anyone know why my Vpp reading on the scope is doubled?

Many thanks.

do you have a 50 ohm load on the generator?

 

[David L. Jones]

I have something simple but I can't seem to find an answer to it.

I am getting a different Vpp measurement on the scope from the signal
generator. When put in a 1Vpp 200KHz square wave from my signal
generator, while the frequency is dead on at 200KHz, I got a reading
of 2 Vpp on the scope. I made sure the signal generator is outputting
Vpp, not RMS. My scope is on DC Coupling.

Does anyone know why my Vpp reading on the scope is doubled?

The signal generator is set to 50ohm output termination. So unless you
add 50ohms to the output, the output voltage will be double what you
expect.

Many generators will allow you to switch the output to "high
impedance" mode and then you will get the output value as indicated on
the generator.

Dave.