ECR Title: Unfied ALS Frequencies	DCC No: E1300697-v1
Date: 9/3/2013
Requester: Daniel Sigg	Impacted Subsystem(s): ISC
Description of Proposed Change(s): Change all ALS frequencies to the nominal H1/L1 frequencies. This is what it should be: H1X/L1X: f=24.407079 MHz, H1Y/L1Y: f=24.482125 MHz, H2X: f=24.440707 MHz, and H2Y: f=24.515730 MHz. And here is what we have: S1000575 24.407079 500-14927 LHO H1 EX no change S1000576 24.407079 500-14927 LHO spare no change S1000577 24.407079 500-14927 LLO L1 EX no change S1000578 24.407079 500-14927 LLO spare no change S1000581 24.440707 500-14927 LHO H1 EY 24.482125 S1000582 24.440707 500-14927 LHO spare 24.482125 S1000583 24.440707 500-14927 LLO L1 EY 24.482125 S1000584 24.440707 500-14927 LLO spare 24.482125 S1000585 24.482125 500-14927 LHO H2 EX 24.407079 S1000586 24.482125 500-14927 LHO spare see E1300659-v1 S1000579 24.515730 500-14927 LHO H2 EY 24.482125 S1000580 24.515730 500-14927 LHO spare see E1300659-v1 Change the H2 IMC frequency to the same as H1/L1. S1000569 24.078360 500-14927 H1 IMC corner no change S1000570 24.078360 500-14927 LHO spare no change S1000571 24.078360 500-14927 L1 IMC corner no change S1000572 24.078360 500-14927 LLO spare no change S1000573 22.993090 500-14927 H2 IMC corner 24.078360 S1000574 22.993090 500-14927 LHO spare see E1300659-v1
Reason for Change(s): The RF sources for the ALS frequencies are partially wrong. This is part due to an initial error and part due to the fact that the third interferometer has been converted into a straight configuration. Since the IMC lengths are all identical now, so should the RF frequencies.
Estimated Cost: ALS RF oscillators on hand, rework and retesting.
Schedule Impact Estimate: none. The change needs to be implemented by the start of HIFO-X.
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: ____________ Essential by date/event: _HIFO-X_____ 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.): E1000482
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, or Deputy Systems Engineer