On 7/24/2013 11:25 AM, K8RI wrote:
The fan dipole on 75 can give much wider, usable areas.
With SS amps I'd like to be able to QSY with all the knob twisting.
Yes. It's easy to make wire spreaders by cutting 1/2-in PVC conduit into
18-in lengths and drilling holes for the wires. If one of the wires is
bare copper, the spreaders can be held in place with wire looped across
the spreader and soldered. I use hard drawn copper that I "make" by
buying #8 bare copper from a big box store, tying one end around a tree
and the other around a trailer hitch, and slowly stretching it until it
breaks. The resulting hard drawn copper has stretched by roughly 10%.
I consider copperweld antenna wire a terrible choice for serious antenna
work. My neighbor, W6GJB, built a 2-wire fan dipole using copperweld and
RG8, and hoisted it between a couple of redwoods with pulleys on both
ends and a weight on one end. It was on the ground the next day -- the
copperweld broke. We rebuilt it with the hard drawn copper.
The Power Point shows another elegantly simple and effective method of
broadbanding many resonant antennas that W6NL teaches in his classes at
Stanford. With SimSmith, you can simultaneously model both SWR and loss,
making it easy to optimize a design.
73, Jim K9YC
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