[Elecraft] Velleman AS9 mat for KX3

[Alan Bloom]

I'm suspicious.  Why are some resistances specified "+/-"?  I'm pretty 
sure it doesn't have a negative resistance.  And the units of volume 
resistivity are ohm-cm (or ohm-m), not ohm/cm.

The fact that it doesn't specify compliance to any industry standard 
also is a concern.  An anti-static mat should comply with "ANSI/ESD 
S4.1" or "ANSI/ESD S20.20".  Those standards specify measuring the 
resistance between two weighted, circular electrodes of a certain size 
and spaced a certain distance apart on the mat.  The resistance should 
measure between 1 Mohm and 1 Gohm, depending on the relative humidity.

Here are the results of some testing I did on anti-static mats a few 
years ago, along with a recommendation for one mat I found that did 
measure within spec:

http://www.mail-archive.com/elecraft%40mailman.qth.net/msg94407.html

The bottom line is, many so-called "anti-static" mats don't do the job. 
  And the problem is, there is no easy way to tell.  Just because you 
managed to build something without damaging any parts doesn't prove the 
mat is working correctly.  This is one area where it doesn't pay to go 
cheap.

Alan N1AL



On 04/17/2016 01:24 PM, Bruce Nourish wrote:
> Hi folks,
>
> I'm adding a 2m unit to my factory built KX3, and wanted to check if the
> specs on this mat were adequate:
>
> http://www.velleman.eu/products/view/?country=be&lang=en&id=382422
>
> surface resistance: ± 10^8 - 10^10 Ω/sq
> volume resistance: < 10^10 Ω/cm
> RTT (point to point): ± 10^8 - 10^10 Ω
>
> It includes a wrist strap with a 1 MΩ resistor. The numbers look to be in
> the ball park of the examples given in the KX3 manual, but I wanted to
> check before I started poking around the guts of my very expensive toy.
>
> Bruce