Vectronics VEC-830K - Manual (Page 6)

VEC-830K Instruction Manual Single Side-Band Filter Kit
Transistors:
If transistors are installed incorrectly, damage may result when power is applied.
Transistors in metal cases have a small tab near the emitter lead to identify
correct positioning. Semiconductors housed in small plastic cases (TO-92) have
an easily-identified flat side to identify mounting orientation. Many specialized
diodes and low-current voltage regulators also use this type packaging. Larger
plastic transistors and voltage regulators use a case backed with a prominent
metal tab to dissipate heat (T-220). Here orientation is indicated by the
nositionine of the colling tab.
Integrated Circuits:
Proper IC positioning is indicated by a dot or square marking located on one end
of the device. A corresponding mark will be silk-screened on the PC board and
printed on the kit's parts-placement diagram. To identify specific IC pin numbers
for testing purposes, see the diagram below. Pin numbers always start at the
keyed end of the case and progress counter-clockwise around the device, as
shown: