[Elecraft] ESD Question!

[Kurt Pawlikowski]

Jim,

    There are *no* dumb questions! In fact, this is a good question and 
not asked nearly as often as it maybe should!

    The biggest issue with ESD is keeping a discharge from going 
*through* you equipment. In *theory*, an ungrounded system offers some 
protection from this, but it is not recommended. If you have any ground 
(third wire or station ground), that will suffice. Usually, the third 
wire ground is used. I believe that's because 1) its ubiquitous and 2) 
because its ubiquitous, it'll be at the same potential with most of the 
things you have in your house which intern means you'll have little 
chance of becoming a "bridge" circuit in a "ground loop" (two grounds 
with different potentials). While this usually isn't an issue, I have 
heard of ground loops with potentially hazardous voltages. Maybe not so 
much for people as for equipment.

    You should be able to check your mat the same way you checked your 
wrist strap. Measure between the alligator clip and the mat itself. You 
should get similar (~1 megohm) results. Its been a long time since I've 
messed with mine, but IIRC, you should be able to make this measurement.

    Now, whether the ground you've chosen is effective is another 
matter. An interesting "revelation" is to measure between your station 
ground and your electrical ground. And, as I understand it, your station 
ground should be bonded to your electrical ground at the panel's ground 
rod. Why? Well, it helps keep lightening from using your ground (and 
consequently, you equipment!) instead of the "designated driver," 
so-to-speak. Of course, any direct hit and all bets are off. In fact, 
because of EMP, you can have electronics that are not even plugged in 
get fried. Isn't that special! {'-)

    I hope this helps.

    Regards,

    kurtt

    Kurt Pawlikowski, AKA WB9FMC
    The Pinrod Corporation
    kurtt at pinrod.com
    (773) 284-9500
    http://pinrod.com

capobs1 at bellsouth.net wrote:
> Good afternoon All.
>  
> They say an un-asked question is the only "dumb" question.  Well, here 
> goes!
>  
> I'm an appliance operator and my technical skills are kinda shallow.  
> I do have a DMM and know how to use it.
>  
> I'm in the planning stage of building my dream transceiver: aka an 
> Elecraft K3.
>  
> After reading through the assembly manual [thanks to its availability 
> on the Internet], it's very clear that I should not try such a  
> project without an ESD Wrist Strap and ESD Mat.  I have these in my 
> possession as we speak.  They were purchased from a commercial company 
> advertising them as ESD items.
>  
> That leads me to my question.  How can I be assured that this Mat IS 
> grounding a PCB [or anything else] during the "build" process?
>  
> I checked the resistance of the Wrist Strap and sure enough there is a 
> 1M Ohm resistor in there.
>  
> I cannot figure a way to check the Mat's grounding.  It's "alligator 
> clip" is attached to my station's woven metal Ground Strap system. 
>  
> Any help would be appreciated.
>  
> Thanks and Best 73.
>  
> Jim.........
> WA4NTM
>  
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