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Problem with phase shifting 33120A and 33250A.

Question asked by vostok on Apr 15, 2011
Latest reply on Apr 21, 2011 by lhornburg
Hello,

I have a setup with 33120A driving a vibrating specimen and 33250A controlling short light pulses (about 1/100th of the vibration period) illuminating the sample.

When I offset the illumination frequency at, say, 1 Hz I see the sample apparently oscillating at 1 Hz as expected (the true oscillation frequency is in the kilohertz scale). What I like to achieve is to set the drive and illumination pulse frequencies equal and control the phase difference of the signals in order to image the my sample at different phases of the oscillation period. I have got the two generators synchronized via the 10MHz clock cable.

When I manually adjust the phase of 33120A (the newer one doesn't have a manual menu option) I see the sample moving corresponding to to the phase I just adjusted.

My problem is that when sending PHAS 180.0 etc. commands to the generators (either one) via GPIB, I see no movement or change in position. A GPIB query "PHAS?" confirms that the generators received my commands.

What seems to be the problem here? Any ideas?

Lauri Kangas, Finland  

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