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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: 1248     Entry time: Thu Jan 20 00:00:07 2011     Reply to this: 1250
Author: Zach 
Type: Electronics 
Category: GYRO 
Subject: EOM circuit 

 I finally got around to re-modifying the EOM resonant circuit. Since adding a parallel resistance at the input didn't seem to work when I tried it before the holidays, I decided to try Solution 1 of Koji's suggestions from this elog post. Below is a picture of the circuit once I was done modifying it. It has 3 cascaded RF transformers at the input followed by an inductor (actually two in series) which is in parallel with the EOM to ground. The transformers are 1:16, 1:4, and 1:2, giving an impedance division of 16*4*2 = 128. Since (as explained in the linked post), the resonant impedance of the circuit without the transformers is estimated to be around 6 kohms, their addition should result in an input impedance on resonance of ~50 ohms. The plot below the picture shows that this is not the case; the result is closer to 140 ohms.

I assume that the problem here is the various stray losses from series resistances (e.g. in the transformers). I am going to take a look at all the data points we have from the various impedances measured using the various circuits and try and come up with a solution that will work.



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