Elecraft K2 Owner's Manual User Manual

Page 23

LECRAFT

Option Components

All component locations on the Control board should now be filled
except for the following:

 C44 (top side of the board near the microcontroller, U6). This

capacitor will not be used.

 J1 and J2 (bottom side). These two connectors are provided for an

audio filter option (KAF2 or KDSP2). An audio filter should not
be installed until the K2 has been completed and tested.

Visual Inspection

Nearly all problems with kits are due to incorrectly installed
components or poor solder joints. You can avoid these problems by
doing a simple visual inspection. A few minutes spent here may save
you hours of troubleshooting time.

Make sure there are no components installed backwards. Check

all diodes, resistor networks, electrolytic capacitors, and ICs. (The
parts placement drawings in Appendix F will be helpful when
checking diode orientation.)

Examine the bottom of the PC board carefully for the following

(use a magnifying glass if available):

 cold solder joints
 solder bridges
 unsoldered pins

Resistance Checks

In the table below, "<" means "less than," and ">" means "greater
than." When measuring resistances that show a minimum value in the
table (such as > 100 k), your resistance reading may be much higher or
even infinite. This is typical when using a DMM (digital multimeter).
If you use an analog meter you may find that some or all resistance
measurements are too low. Note: Some digital multimeters will flash
their display to indicate an infinite resistance.

Perform the resistance checks listed below to ensure that there are

no shorts in the most critical control circuits. (The Control board will
be fully tested in a later section.)

Test Point

Signal Name

Res. (to GND)

P2 pin 1

12V

> 10 k

U5, OUT ("5V" pin)

> 2 k

U4, OUT ("8V" pin)

3 - 7 k

Q1 collector

> 1 M

Q2 collector

> 1 M

U3 pin 8

12V IN

> 10 k

U6 pin 13

OSC1

> 100 k

U6 pin 14

OSC2

> 100 k

U6 pin 29

DASH

70 - 90 k

U6 pin 30

DOT/PTT

70 - 90 k

U8 pin 2

VPWR

> 100 k

U8 pin 15

VBIAS-XFIL

> 100 k

U8 pin 16

VBFO

> 100 k