Topband: Strange resistance between Beverage ground rods

[Mike Waters]

Good answer, Greg. DC is certainly not the best way to measure an RF ground.

I wonder what the difference would be if we used 1.8 MHz instead of 100 Hz?

I thoroughly soak the earth around the rods here with Epsom salt (magnesium
sulfate). It *really* decreases the ground resistance! The difference
between a newly-driven-in rod, and after applying that treatment, is
immediately obvious by listening to the receiver.

Of course, as N3OX once quipped, "I'm fond of adding elemental copper in
thin filaments stretching radially away from the ground rod for some
distance". ;-)

73 Mike
www.w0btu.com

On Nov 15, 2016 10:16 AM, "Greg - ZL3IX" <zl3ix at inet.net.nz> wrote:
> I came across this problem when I first started using Beverages in 2008.
I have come to the conclusion that the DC resistance measurement is
corrupted by electrochemical effects between the grounds, ie potential
differences. I then changed to an AC measurement. I made a simple 100-or-so
Hz oscillator using an op amp and  I put this between the two wires in
parallel at the feed and the ground. There is a 100 ohm resistor in series.
I measure the AC voltage across the Bev and the voltage across the resistor
and thus deduce a loop resistance through the ground.