ECR Title: Add a 45.5MHz phase-locked OCXO	DCC No: E1500371-v1
Date: 8/27/2015
Requester: Daniel Sigg	Impacted Subsystem(s): ICS
Description of Proposed Change(s): We propose to add a 45.5 MHz phase-locked OCXO to clean up both amplitude and phase noise. Custom frequency oscillators have a long lead time and we propose to build 2 PLO chassis per detector.
Reason for Change(s): Compared to the original design we are using very large modulation indices. This makes us more sensitive to RF AM. Furthermore, the 45.5MHz is generated as the 5th harmonics of the 9.1MHz which results in poor amplitude and phase noise.
Estimated Cost: $4500/ifo for PLO&OCXO; WAG $3000/ifo for chassis & slow readback electronics.
Schedule Impact Estimate: can go on in parallel.
Nature of Change (check all that apply): Safety Correct Hardware Correct Documentation	Improve Hardware Improve/Clarify Documentation Change Interface Change Requirement
Importance: Desirable for ease of use, maintenance, safety Desirable for improved performance, reliability Essential for performance, reliability Essential for function Essential for safety	Urgency: No urgency Desirable by date/event: _after O1 ____ Essential by date/event: ______________ Immediately (ASAP)
Impacted Hardware (select all that apply): Repair/Modify. List part & SNs: ______________________ Scrap & Replace. List part & SNs:_____________________ Installed units? List IFO, part & SNs: _________________ Future units to be built	Impacted Documentation (list all dwgs, design reports, test reports, specifications, etc.): CDS rack drawings, EtherCAT system drawing, RF distribution drawing
Disposition of the proposed change(s): The disposition of this proposed engineering change request is to be completed by Systems Engineering and indicated in the “Notes and Changes” metadata field in the DCC entry for this ECR. The typical dispositions are as follows: Additional Information Required: in which case the additional information requested is defined. The ECR requester then re-submits the ECR with the new information using the same DCC number for the ECR but with the next version number. Rejected: in which case the reason(s) for the rejection are to be given Approved Approved with Caveat(s): in which case the caveat(s) are listed TRB: the ECR is referred to an ad-hoc Technical Review Board for further evaluation and recommendation. It is the System Engineer’s (or designee’s) responsibility to organize the TRB. The System Engineer (or designee) then makes a technical decision based on the TRB’s recommendation. Links to the TRB’s documentation (charge, memos, final report, etc.) are to be added to the “Related Documents” field for this ECR. CCB: a change request for approval of additional funds or schedule impact is to be submitted to the Configuration Control Board. Links to the CCB’s documentation (CR, etc.) are to be added to the “Related Documents” field for this ECR. Concurrence by Project Management: Acknowledgement/acceptance/approval of the disposition is to be indicated by the electronic “signature” feature in the DCC entry for this ECR, by one the following personnel: Systems Scientist Systems Engineer Deputy Systems Engineer