Control of coaxial cable propagation delay for a beam phase monitor

The average position of the beam near the crest of the accelerating voltage in the Stanford Linear Collider linac must be kept stable to a fraction of an S-band wavelength or about 0.5 ps. Temperature stabilized S-band RF distribution cables and phase monitors have been installed along the 3 km linac to minimize the effects of the up to 40 degree F daily temperature excursions in the support building environment. In this paper, we present test results of the equipment designed to determine the stability of the RF distribution system by comparing it directly to the beam. In particular, efforts to stabilize the propagation delay of the system's coaxial cables will be described