Elecraft KRC2 Manual User Manual

Page 5

Firmware Requirements

To use the KRC2 with a K2 or K2/100 transceiver, you will need K2 main microcontroller
firmware revision 2.01 or later and either the KIO2 or KPA100 options.
Note: The main K2 microcontroller is U6 on the K2 Control board. To check your firmware
revision, hold any K2 pushbutton when powering up the K2. When you release the pushbutton, the
revision will be shown on the LCD (left side).

Assembly

A fine-point, temperature-controlled soldering iron (700-800 degrees F maximum) is

required to assemble the printed circuit board. A higher-wattage iron or one with a wide tip
may damage components, pads, or traces. We also recommend the use of a Panavise (or
equivalent bench vise) and an illuminated magnifying glass to facilitate PCB and connector
assembly. Additionally, flush-cut wire cutters are recommended for steps where component
leads must be cut close to the circuit board.

To avoid soldering conflicts, install components only in the order described below.

Double-check all values before soldering, since removing parts from double-sided printed circuit
boards can be difficult.

The leads on small capacitors can be fragile. When handling capacitors in the

following steps, do not pull on the leads or bend them excessively.

Locate the KRC2 PCB and identify the top and bottom sides. The side of the board with

outlines of ICs U4-U7 and most other components is the top; the side with the "KRC2" label is
the bottom. If an assembly step does not specify top or bottom, the component should be installed
on the top side.

Install the two 0.1-µF (104) capacitors with 0.1" (2.5 mm) lead spacing on the top side of the

board:

__C25, __C60

Solder C25 and C60

. Trim the leads of C25 as short as possible, using flush-cutters if

available. If the leads are not kept very short, they will interfere with installation of J5 on the
bottom side of the board.