On Sun, Sep 22, 2019 at 03:15 AM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:
On Sun, 22 Sep 2019 at 08:10, Dr. David Kirkby <
drkirkby@...> wrote:
I fail to see the need to worry if the active devices is connected across
a 50 ohm resistor. 50 ohms is effectively a short circuit as far as static
is concerned.
Here¡¯s a video from dave Jones of EEVBLOG measuring the DC resistance of
antistatic mats.
Two DVM probes are put next to each other, the meter, which can read upto
300 M ohm can measure anything.
I should have said that the meter can not measure the resistance - it is
over 300 M ohm.
You are not going to zap the NanoVNA with static on its RF input terminals.
--
Dr. David Kirkby,
David, antistatic mats are typically constructed of 3 layers: the outside being a work surface of some plastics composition and the middle is the conductive portion. What was done in the video was not a valid test. He should have used a surface charge meter to measure.
The whole idea is to bleed off any charges, not to 'short' them at the work surface.
The middle layer of the work mats is made up of a carbon weave and yes, it conducts. Folks also need to know that these mats need to be grounded or they're useless. Many times in dry weather, I've gotten up from my chair and placed my hand at the edge of the mat to be greeted with a nice zap every so often.
Shocking!
Larry
