Elecraft KX3 User Manual

ELECRAFT KX3 Application Note

Installing the Speaker Grille Cloth

Revision A, July 30, 2012

Copyright © 2012, Elecraft, Inc., All Rights Reserved

Background

Some KX3 owners have reported issues with the internal speaker. During our search for the cause, we found that the fabric
grille could vibrate if the volume was very high, so we started removing the grilles.

Based on an evaluation of field reports and our own further testing, we've concluded that, in nearly all cases, edge-to-edge
contact between the top and bottom covers is to blame, not the grille.

As long as the grille is not creased and is kept flat when the speaker screws are tightened, it should stay ou t of contact range
of the speaker cone.

Order KX3GRILLEKT to obtain the grille and for new speaker mounting screws.

Tools Required

1. ESD Protection (see Preventing Electrostatic Discharge Damage, below).

2. #1 size Phillips screwdriver. To avoid damaging screws and nuts, a power screwdriver is not recommended.

3. Needle nose pliers.

4. 5/64” Allen Wrench for the VFO know (sup pl i ed wi t h t he KX 3) .

5. Soft cloth or clean, soft static dissipating pad to lay cabinet panels on to avoid scratching.

Preventing Electrostatic Discharge Damage

Your KX3 contains many components susceptible to electrostatic discharge damage (ESD). ESD damage may occur with
static discharges far too little for you to notice. A damaged component may not fail completely at first. Instead, the damage
may result in below-normal performance for an extended period of time before you experience a total failure.

We strongly recommend you take the followi ng a nt i-st at i c precautions (listed in order of import ance) to ensure there is no
voltage difference between the components and any object that touches them:

 Wear a conductive wrist strap with a series 1-megohm resistor that will constantly drain off any static charge that

accumulates on your body. If you do not have a wrist strap, touch a ground briefly before touching any sensitive
parts to discharge your body. Do this frequently while you are working. You can collect a destructive static
charge on your body just sitting at the work bench.

WARNING

DO NOT attach a ground directly to yourself without a current-limiting resistor as this poses a serious
shock hazard. A wrist strap must include a 1-megohm resistor to limit the current flow. If you choose to
touch an unpainted, metal ground to discharge yourself, do it only when you are not touching live circuits
with any part of your body.

 Use a grounded anti-static mat on your work bench (see below).

Choosing an Anti-Static Mat

An anti-static mat must bleed off any charge that comes in contact with it at a rate slow enough to avoid a shock or short
circuit hazard but fast enough to ensure dangerous charges cannot accumulate. Typically, a mat will have a resistance of up
to 1 Gigaohm (10
mat that comes with published resistance specifications and clean it as recommended by the manufacturer. Testing has
shown that many inexpensive mats that do not specify their resistance have resistance values much too high to provide
adequate protection, even after they were cleaned and treated with special anti-static mat solutions.

9

ohms). Testing a mat requires specialized equipment, so we recommend that you choose an anti-static

Elecraft • www.elecraft.com • 831-763-4211

Suitable anti-static table mats are available from many sources including:

7

 U-line (Model 12743 specified at 10
 Desco (Model 66164, specified at 10

TM

 3M

Portable Service Kit (Model 8505 or 8507, specified at 106 to 109 ohms)

ohms)

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to 108 ohms)

Procedure

Observe ESD precautions when working inside your KX3. Wear an ESD wrist strap or touch an

unpainted, metal ground frequently while working.

Separating the KX3 Case Halves

Open the KX3 just as you would to install or remove batteries (see Internal Batteries in your Owner’s

Manual for details about how to do this).

If batteries are installed, remove them.

Disconnect the flex cable and the battery cable as shown in Figure 1. The owner’s manual cautions against
disconnecting the flex cable. That is because the connectors on the flex cable are not designed for heavy use. It is
necessary to disconnect the ribbon cable in this case. Gently work the connectors loose holding the stiff section
attached to each connector. Do not pull on the ribbon cable itself.

Figure 1. Opening the KX3.

Set the bottom cover assembly aside in a safe place.

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Removing the VFO Encoder

Remove the VFO knob as shown in Figure 2.Use your fingernails or a soft tool to free the finger grip. A sharp tool
may scratch the knob.

Figure 2. Removing the VFO Knob.

Turn the assembly over so you can see the back of the encoder. There are two types of encoders used in the KX3. One
has a shield soldered to the back of the encoder and the other has a shield that mounts onto the front. If your encoder has a
soldered shield, there is a lock washer on the inside of the front panel. Take care not to lose the lock washer between the
front panel and the CP board when you remove the encoder in the following steps.

Figure 3. Encoder Types.

Elecraft KX3 Application Note – Installing the Speaker Grille Cloth Page 3 of 9