Elecraft KX3 Speaker Grille Instructions - Manual

Elecraft • www.elecraft.com • 831-763-4211
E
LECRAFT 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 out 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 (supplied with the KX3).
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 following anti-static precautions (listed in order of importance) 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
9
ohms). Testing a mat requires specialized equipment, so we recommend that you choose an anti-static
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.