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Message ID: 299     Entry time: Mon Jul 2 12:29:01 2018
Author: Koji 
Type: Electronics 
Category: Characterization 
Subject: Impedances of individual components (3IFO EOM) 

[Rich Koji]

The impedances of the individual components from the 3IFO EOM (before modification) were tested.
Each component was modeled by LISO. The LISO model (in PDF and txt) are attached at the end of the entry.

Coils
There are three inductors taken from the EOM unit. They showed the Q ranging from 150~300.
Their impedances are compared with the coil taken from the 9MHz port of the spare EOM (=current LHO EOM).
The inductance of the 8.7MHz inductor indicated higher L but still higher Q.

Todd made a replica of the 45.3MHz coil. He used a silver plated wire and it actually showed highest Q of ~400.

Crystal capacitance
The crystal capacitances were measured by attaching a test rig on the DB15 connector of the crystal housing. The rig was calibrated such that the impedances of the attched components on the rig were measured. They showed somewhat similar feature with parasitic resonances at ~50MHz. Above this frequnecy the capacitance went down (i.e. Abs(Z) went up). This indicates there are stray series LCR in pararrel to the crystal. Not sure what is the cause of this.

The central (24.1MHz) port showed smaller capacitance. This probably means the plates for the central port is smaller. Not sure the actual dimensions of the plates for this unit.
 

Attachment 1: impedance_coils.pdf  801 kB  Uploaded Mon Jul 2 13:30:39 2018  | Hide | Hide all
impedance_coils.pdf
Attachment 2: impedance_xtals.pdf  682 kB  Uploaded Mon Jul 2 13:30:47 2018  | Hide | Hide all
impedance_xtals.pdf
Attachment 3: q_coils.pdf  956 kB  Uploaded Mon Jul 2 13:30:55 2018  | Hide | Hide all
q_coils.pdf
Attachment 4: component_models.pdf  680 kB  Uploaded Mon Jul 2 13:31:04 2018  | Hide | Hide all
component_models.pdf component_models.pdf component_models.pdf component_models.pdf component_models.pdf component_models.pdf component_models.pdf component_models.pdf
Attachment 5: liso_models.zip  3 kB  Uploaded Mon Jul 2 13:31:37 2018
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