Hi Guys
Stay away from aluminum, the aluminum oxide dielectric is a terrible
complication around 2 MHz, it become a capacitor and a diode and will generate
a lot of noise in presence RF currents.
There is no way to avoid the diodes at the connection with different materials,
like at the ground plate. When these electrical junctions are very well they
will work well for few months, than the noise will start around Sunset when the
RF field from AM BC are more intense, the RF will be there, even if you are far
from BC station, the propagation peak is near Sunset.
Galvanic corrosion and diode formation is inevitable. Same problem is very
common on rotor, mast and tower contacts originating birds on 1810, 1820 and
every 10 KHz, most of this signals are originate on your own tower. Just
grounding the with a solid contact with the tower can kill a lot of noise.
I've seen several situation of aluminum joints becoming a strong noise source.
The same joints are not a problem on 80 or 40m, the issue is just around 2 MHz
Save yourself a lot of problems, aluminum an 160m antennas are not a good
combination.
73's
JC
N4IS
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