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Entry  Thu Jan 20 00:00:07 2011, Zach, Electronics, GYRO, EOM circuit circuit_picture.pngimpedance_plot_1_19_11.png
    Reply  Thu Jan 20 17:04:42 2011, Zach, Electronics, GYRO, EOM circuit impedance_plot_1_20_11.png
       Reply  Fri Jan 21 18:15:58 2011, Zach, Electronics, GYRO, EOM circuit impedance_plot_1_21_11.png
Message ID: 1250     Entry time: Thu Jan 20 17:04:42 2011     In reply to: 1248     Reply to this: 1252
Author: Zach 
Type: Electronics 
Category: GYRO 
Subject: EOM circuit 

After looking at the impedances seen in all the different configurations, I decided that the most recent result just didn't make any sense. So I re-took the measurement, and the impedance magically came out to 46 ohms (see below).

What I think happened was that I changed the frequency range of the sweep after I had completed the calibration of the impedance test kit, so the analyzer was extrapolating out to where I was measuring. Another thing I noticed was that the results were different depending on whether I used single shot or continuous triggering. This final result was done with proper calibration and using single shot the way I was shown to do it the first time.

impedance_plot_1_20_11.png

Finally this business can be put to rest (unless there is reason to believe that 46 ohms is not close enough to 50 ohms---I'm not sure what sort of reflected power we are likely to be able to handle.)

RA: 46 Ohms is OK, but not too hot. How about trying out some trimmable components too? When you finish, I recommend filling the box with some kind of goo (like RTV) so that it doesn't all rattle around. That's what the professionals seem to do.

 

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