Greetings:
Preparations continue for TransAtlantic II, the test transmissions from here
in Eastern Ontario on 137.710 kHz are now heard widely in the USA and
Canada.
Moving forward through the lists of things and issues to be worked on, the
subject of WIRE for LF antennas comes up. The objective of this email is to
have a discussion with active LF amateurs that will ensure for me at the end
of the day that the best alternatives have been discovered and considered
for use here.
The current antenna here for the test transmissions is made from what we
here call common antenna wire, 7 strands of semi hard copper wire, commonly
known as 7/24. For LF the type of wire is marginal, when used for long
spans it stretches and anneals, becomes eventually very brittle and fails.
A lousy wire solution for long spans associated with LF antennas. The LF
test antenna here is far from optimum because I simply do not dare to
stretch the wire harder with the rope that pulls the antenna away from the
supporting tower.
The alternative selections available here are very limited. There is a
reasonable quantity of semi hard drawn solid copper wire #12, commonly used
by the Broadcast Station industry. I use this for MF/HF antennas but it is
also subject to annealing and stretching.
We have available an insulated wire known variously as "FlexWeave", similar
to Litz wire but without the shellac to hold the wire together. This is
around 75 and 150 strands in the two sizes that are usually available. The
issue here again is strength, 150 Meter spans do not last very long.
The last is the good old copper clad steel wire, not much copper any more
but usually pretty good for long spans. Sources of this product are
limited, a good source here in Canada would be a help.
What are the other alternatives that you are using in your setup? Why are
they good? What is the usual cost in your area? If you were looking at
spans of up to 300 Meters what would you use for an antenna wire?
Not a glorious subject, but one which is important to the LF community.
Your comments are solicited.
Larry
VA3LK
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