Lie on the Beam by John Victor Peterson

Down in the radio beam station, Wagner, Ward and a very unsteady Portiz surveyed each other in stunned dismay for about ten seconds.

Fred Ward was struggling to put into speech that which he felt within. Here was crisis. Here was an intermingling of human and mechanical failings which had built up almost to the point of nervous dissolution in the men concerned. Probably of secondary importance now was the fact that two terrestrial cruisers were nearing perihelion at the sun; they depended absolutely on the keyed radio wave which would leap across their trajectory and crackle in their attentive receivers. But that keying device was out of commission and in all that great bank of two hundred keyers there was not another silent. There was not another which they could safely adjust to the cruisers' course without imperiling the safety of some other craft.