To: Edgar Castro

From: Jon Hagen

Date: Feb. 2, 2001

Subject: Report for January, 2001

The two monoplexer drivers were modified to improve the turn-off time from 20 microseconds to 5 microseconds. The opto-coupler inputs were modified to improve their match to the 50-ohm control.

While testing the 430 Gregorian radar system, the old collector in use on that side arced and burned out its rexolite window. It was found that the access plate - added when extensive mechancial repairs were made about a year ago - had been installed with RTV compound on the contacting area. This had been done to make the unit gas tight but the RTV left the flange insulated and arcing occurred across the insulated areas between the bolts. The flange was refaced and the number of bolts was doubled. This collector will be retired when the second new collector is finished. The as-built drawings for the first new collector were consolidated and updated and sent to the shop at the Ithaca lab, where two additional units are being made

I wrote a memo describing proposed hydraulic safety damper system for the Gregorian dome and the carriage house. A copy was sent to Jose' Maldonado, who is investigating the feasibility of building these systems here. The memo could also be sent out as an RFP to hydraulic

consultants, who would likely give us some valuable advice, even if we design and build the system ourselves.

We installed anlog meters at the three tiedown control stations to read the cable tensions and to provide manual control, independent of the Little Star control computers.

A new 1-chip (LTC1562 quad second-order filter) version of radar matched filter was designed - the additional filter is needed for upcoming dual-beam radar operation.

A two-page B-size schematic was drafted for the downstairs IF/LO system. This complete but somewhat simplified schematic provides an overview to the schematics of the individual units and can replace the original D-size schematic which doesn't indicate the boundaries of the physical units.