We present measurements of the sub‐kilovolt X‐ray emission from imploding wire arrays on the 1 TW BLACKJACK 3 pulsed power generator. The plasma is created by driving a 1 MA, 100 ns current pulse through a cylindrical array of 12 fine wires. The wires form individual plasmas which then implode to become a single plasma on the axis of the array; this hot, dense plasma is an intense source of soft X‐rays. Calorimeter measurements show that maximum soft radiation yield is produced from arrays having a linear density of 100 to 200 &mgr;g/cm; for such arrays the implosion occurs within 20 ns of the current peak. The dependence of the total yield on mass is largely independent of wire material. The radiation pulsewidth measured with an unfiltered X‐ray diode increases monotonically with array mass from a 25 ns FWHM observed for 50 &mgr;g/cm arrays.The soft X‐ray spectra radiated by the imploding plasmas approach a blackbody spectrum with increasing wire mass and atomic number. Tungsten and silver plasmas radiate continuum spectra in the sub‐kilovolt range; no lines are discernable in either case. Stainless steel plasmas radiate a similar continuum, but L and M lines are present for lower mass arrays. The continuum radiated by aluminum plasmas is less smooth, and significant K and L lines are present for lower masses. Carbon plasmas radiate intense K and L lines and an optically thin continuum. Similar soft X‐ray emissions can also be achieved with small imploding gas jet plasmas.