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The power, efficiency and operating frequency specifications can be met over a wide range of breakdown voltage IMPATT diodes. The AM noise figure appears to be the most critical diode specification and the higher breakdown voltage diodes appear to give superior performance. Diode reliability for the IMPATT diodes is a serious problem and degradation with subsequent failure is the norm. A prototype oscillator was assembled. This oscillator met power output, electronic tuning, frequency pulling and pushing and power pushing. The oscillator failed to meet the specifications of AM noise and power pulling.

A new, modified plated heat sink process has been applied to the new zinc diffused wafers grown for this program. The resulting devices have been successful in terms of power and efficiency at 14.85 GHz. The AM noise level of these devices is presently being evaluated. A new, simple AM noise measuring system has been assembled which permits rapid evaluation, although the accuracy is not as high as the standard system described earlier. The initial version of the copper cavity has been evaluated. This oscillator operates much more consistently than previous cavities in that difficulties associated with RF contacts of the cavity parts have been eliminated. However, RF leakage is evident from the bias leads and the tuner mechanism is presently over compensating the frequency with temperature. These characteristics are in the process of being corrected.