Vectronics VEC-821K - Manual (Page 7)

VEC-821 K Instruction Manual Super CW 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 positioning of the cooling tab.
I n t e g r a t e d C i r c u i t s :
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 1C 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: