Designed to isolate test equipment from a network-under-test so that the twisted pair communication network's performance can be measured without affecting its integrity, these new wide-band baluns use high-speed signal conditioning techniques to increase frequency response by an order of magnitude over existing products. The baluns are said to permit the insertion, transmission and return loss, as well as other qualities of signals encountered in fibre channel, Gigabit Ethernet and other types of networks to be easily and accurately measured.The HFB050150, HFB050100 and HFB050078 baluns convert a balanced differential-mode 150 ohm, 100 ohm and 78 ohm signal, respectively, to a grounded unbalanced 50 ohm signal with 15 dB return loss from 1.0 MHz to 1.2 GHz. The baluns have a terminator network and correlation data for periodic calibration verification and come with terminal pins for connecting network to balun.