[30m] My solution for joining copper and aluminum wire

[Jason Hsu, AA0II]

I use pre-tinned stranded copper wire (speaker wire is a good source).
I strip the copper wire and wrap it around the aluminum wire (after
using sandpaper to scrape off the oxide layer).  Because each strand
contacts the exposed aluminum in several places, the contact is solid.
Because the strands are pre-tinned, the direct copper-to-aluminum
contact is avoided.  For good measure, I also wrap a few turns of a
short length of pre-tinned solid copper wire around the aluminum wire so
as to help hold the stranded wire in place.  Then I use epoxy to hold
the assembly even more firmly in place.  During the whole process, I
disconnect all other radials and continuously monitor the impedance with
my antenna analyzer so that I know the connection is there.

Jason Hsu, AA0II