Hello Herb and fellow Top Banders,
When I had Beverage antennas here I was never able to read the ground
resistance here as well. The reason it did not work here is there was actually
a small DC voltage difference between grounds apparently developed by galvanic
means or currents in the earth. This voltage does not allow a DC resistance
meter to read correctly.
As a side note there is a 1,000,000 volt DC power generation line running
from Celilo Oregon to Sylmar California that uses the Earth as one conductor.
Its no wonder here there is DC across portions of the ground. Just look up
Celilo converter station if you are curious. 3200 megawatts transported from
Oregon to California through the ground! This line is within 20 miles of my
farm. This may or may not be partly responsible for the DC difference on mine
or others Beverage antennas.
Lee K7TJR OR
I have reflection transformers at the end of every two wire Beverages which I
try to test by measuring the wires on the feed end. I remove the transformer
from the two wire WD1-A and check the resistance between the two wires which
tells me that through the reflection transformer I have continuity. It measures
about 40 ohms wire to wire, this is done when I notice any performance change
of the antenna. Now come the next test that baffles me completely. When I
measure from either wire to my ground rods alone, to see what the return
resistance is, I get reading
in the vicinity of 20K across the 900 foot run. I understand that if
the reading was very low it would defeat the whole Beverage principle.
But is 20K Ohms reasonable, very good, or marginal? I use three foot foot rods
at either end and when I pull one out yesterday before moving it the bottom 1/4
was moist and muddy. That Southern end of several reversible Beverages is
located about 100 feet or less from a salt marsh or salt pond. I also have to
such antennas made up of ladder line a DX Engineering components. They all
appear to be working well even though large grass has reach and covered portion
of some of them.
But my question is what is a reasonable or good return ground resistance for a
600' or 900' Beverage. I haven't found any sources of information expect the
saying that the higher Resistance the better. Is this correct?
Herb Schoenbohm, KV4FZ
_
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|