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Elecraft K3
12VDC OUT Current Modification
Revision C, December 22, 2016
E740176
Copyright © 2016, Elecraft, Inc. All Rights Reserved
Introduction
This modification raises the current available from the 12VDC OUT connector on the K3 from 0.5A to 1.0A. It
involves replacing three components on the K3 RF board: diode D34, choke RFC 48 and resettable fuse F2. This
modification applies only to older K3 transceivers. Later K3 transceivers and all K3
S transceivers provide 1.0A
capability from the 12VDC OUT connector.
Parts and Tools Required
You will need a temperature-controlled ESD-Safe soldering station, fine solder, and your normal hand tools such
as needle nose pliers and diagonal cutters. In addition, you will need de-soldering tools such as a solder-sucker or
high-quality de-soldering wick. The action of de-soldering wick is often improved by adding a small amount of
pure rosin-based liquid soldering flux.
A kit containing the required parts is available from Elecraft. Order K312MDKT
QUANTITY DESCRIPTION
ELECRAFT PART
1 Choke, 10uH 1.28A E690303
1 Diode E560063
1 Resettable Fuse, 1.1A E980223
1 Label, 1.0A SWITCHED, Mylar E980226
Procedure
A grounded wrist strap and ESD dissipating mat are recommended whenever you work inside your K3.
Optionally, touch a bare metal ground frequently while working.
Disconnect power and all cables from your K3.
Whenever you remove screws from a panel, if one screw seems too tight to loosen without
damaging it, first loosen the other screws then try again. Sometimes one screw binds in its
hole when the other screws are tightened.
Remove the screws from the rear section of the K3’s bottom cover shown in Figure 1. If either of the two
screws indicated turns but does not unscrew, the spacer it screws into inside is loose. You’ll need to remove the
front section of the bottom cover and hold the spacer with long-nose pliers or strong tweezers to remove the
screw. Later you will be instructed to remove the K3 top cover. When you do that locate the screw from above the
pc board that threads into the spacer and tighten it securely.
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