Elecraft KX3-4M - Manual (Page 12)

12
Installing the KX3-2M or 4M Module
Preparing for Installation
Preventing Electrostatic Discharge Damage
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:
 Leave the KX3-2M or 4M PC board in its anti-static packaging until you install it.
 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).
 If you pick up a PC board that was not placed on an anti-static mat or in an anti-static package,
touch first a ground plane connection on the board such as a connector shell or mounting point.
 If you use a soldering iron to work on a circuit board, be sure your iron has an ESD-safe grounded
tip tied to the same common ground used by your mat and wrist strap.
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.
Suitable anti-static table mats are available from many sources including:
 U-line (Model 12743 specified at 10 7
ohms)
 Desco (Model 66164, specified at 10 6
to 10
8
ohms)
 3M TM Portable Service Kit (Model 8505 or 8507, specified at 10 6 to 10 9 ohms)