To: Edgar Castro

From: Jon Hagen

Date: Feb. 4, 2000

Subject: Monthly report for December, 1999 and January, 2000

The half-height 430 MHz waveguide calibration kit (three waveguide shorts) was built in Ithaca and shipped to Arecibo where it was used to tune two waveguide-to-coax transitions (also made in Ithaca) and to tune the recently repaired waveguide collector.

An improved wheel bearing design was made for this collector; the old wheels and bearings were badly worn. Eight new hub/bearing assemblies were built in Ithaca and shipped to Arecibo. This design will also be used in the new higher power collector.

The half-height turnstile was also fabricated in Ithaca and delivered to Arecibo. This unit was designed entirely using a finite element program (HFSS) and was built with fixed (non- adjustable) shorts. Testing showed that the return loss and isolation are both better than 35 dB at 435 MHz. Bolting a thin shim into the end of one of the fixed shorts should move the optimum frequency down to 430 MHz, with only a negligible effect on the polarization purity. The design of the waveguide run from the collector down to the feed cabin and turnstile is being coordinated with the mechanical engineering department.

A new smaller and simpler driver was designed for the PIN diode receiver protectors used in the 430 MHz radar system. The new drivers will be built for use in both the carriage house and the Gregorian dome.

California Tube Labs reports that they are almost finished repairing a Litton L3403 klystron from Millstone. Arecibo's klystron is the second or third in line for repair.