Control Board - ELECRAFT K 2 Owner's Manual

K2 Manual 1/24/99 V.XC ©1999 Elecraft

4. Control Board

The control board is the "brain" of the K2. It monitors all signals
during receive and transmit, and handles display and control functions
via the front panel board. The microprocessor, analog and digital
control circuits, automatic gain control (AGC), and audio amplifier are
located on this board.
Components
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Review the precautions described in the previous section
before handling any IC's or transistors. These components can be
damaged by static discharge, and the resulting problems are often
difficult to troubleshoot.
Open the bag of components labeled CONTROL and sort the
parts into groups (resistors, diodes, capacitors, etc.). If any of the
components are unfamiliar, identify them using the illustrations in the
parts list, Appendix A. Doing a components inventory is optional.
Locate the control board. It is the smallest of the three K2 PC
boards, labeled "K2 CONTROL" on the front side, in the lower right-
hand corner. The lower left-hand corner is notched.
Open the bag labeled MISCELLANEOUS and empty the
contents into a small, shallow box or pan. This will prevent loss of any
of the small hardware, while still allowing you to locate items as
needed.
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The Allen wrenches are located in a small bag with the
MISCELLANEOUS items. These wrenches may have been oiled
during manufacturing. Remove the wrenches and wipe off the oil, if
any, then discard the bag.
Field Test Notes: Two different sizes of small crimp pins were
inadvertently purchased for the field test kits. Two of the pins are for
the speaker connector, and the other three--which are different--are for
the test probes (counter and voltmeter). The test probe crimp pins (3)
and housings (2) are bagged separately and labeled PROBES.
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There are four sizes of black-anodized, 4-40 machine screws
provided with the kit. The relative sizes of the screws are shown below
for identification purposes (not to scale). The 3/16" (4.8mm) pan-head
screws are the most numerous, and will be referred to as chassis screws
throughout the manual. There is only one Flat-head 3/16" (4.8mm)
screw in the kit.
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