RC asked: > Hi Gang > I am slightly confused! When using ESD protective > measures you should use: > 1) a wrist strap connected to > 2) an anti-static mat. > 3)You should build/work on the anti-static mat to be > certain that all components (and you)are at the same electrical > potential there by minimizing any ESD damage. 4)should you connect the > anti-static mat to the carpet with a long clip lead? > 5)or house electrical ground?
------------------------------------------------- Here's the scoop from the KX1 manual. It's typical of the Elecraft manuals: Preventing Electro-Static Discharge Damage Problems caused by Electro-Static Discharge (ESD) may be very difficult to troubleshoot because damaged components may still operate somewhat rather than fail completely. We strongly recommend you take the following anti-static precautions (listed in order of importance) to avoid trouble: . Leave ESD-sensitive parts in their anti-static packaging until you install them. The packaging may be a special plastic bag or the component's leads may be inserted in conductive foam. Parts which are especially ESD-sensitive are identified in the parts list and in the assembly procedures. . Wear a conductive wrist strap with a series 1 megohm resistor. 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. DO NOT attach a ground directly to yourself as this poses a serious shock hazard. . Make sure your soldering iron is ESD-safe and has a grounded tip . Use a grounded anti-static mat on your work bench. ------------------------------------------ "Grounded" means connected to ground. The mains ground is normally used for this. In general it's a bad idea to have a ground connection separated from the mains ground. (In many places it's a violation of the electrical codes.) It *is* a good idea to make sure your mains grounds are connected! A very simple tester is available in almost any hardware store that plugs into an outlet. It tells you if the mains hot and neutral are connected to the right sides of the outlet and whether the ground is connected. It's rather astonishing to me (and un-nerving) just how many outlets in new homes and recently re-wired homes have no ground connection at all! Your carpet is not conductive. That's why you can develop a huge static charge on it. Connecting a wire to it won't do much. The idea of the wrist strap is to bleed off any charge you do accumulate so that even if you have a 'killer' carpet in the room, your body will be safely at ground potential when you touch the ESD-sensitive parts. You can accomplish this just as well without a wrist strap by briefly touching a known good, unpainted ground before touching the parts, but be aware of the warning to do this *frequently*. Squirming around on a cloth seat or sliding our foot on the floor can produce a killer static charge in an moment, so keep touching that ground before picking up each part. Finally, be aware that it's not just individual parts that need protection. Normally parts in a circuit will have a dc path to ground through resistors, coils and other components that protects them from most ESD dangers but, when you pull a board out of the rig, some circuits are opened by disconnecting the cables and connectors. It's rare to damage the assembled rig unless there's a huge pulse such as a near strike by lightning, but individual boards should be treated with the same respect you'd give the most sensitive individual component. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
