During the August-September 1999 test beam in H8 at CERN three half-modules
, equipped with different types of fast binary Front End electronics, have
been tested. The results indicate that all three SCT electronics candidates
satisfy ATLAS efficiency and noise occupancy requirements, Tn addition, a
study on the effect of detector bias voltage on efficiency (ballistic defic
it) is reported. (C) 2001 Elsevier Science B.V. All rights reserved.