Topband: Simple motor driven telescoping aluminum vertical for low bands?

[George & Marijke Guerin]

Hi Kristinn,

I, personally, believe Simple and Telescoping are probably not compatable.
A mast 12m / 40 ft high probably needs to be made of 50 mm diameter 3 mm
wall tubing - 2 inches OD x 0.125" wall, guyed at center and top to handle
wind and icing.  The top guy lines can be metallic for top loading...  get
as much loading as you can,.  I would try to resonate the antenna close to
the bottom of the band, and then use a good grade of RG-213 to the shack.  A
simple L-net tuner will do the matching at the radio end of the coaxial
cable.  If you can find it a TenTec L-net tuner. model 229 or 238, it does
well, and has a terminal on the back for extra capacity for the Low-Z match.
You may need as much as 2500 pfd shunt capacity to get a match.  The
inductance will be OK, somewhere between maybe 2 and 10 uHy, depending on
frequency and length of coax between the radio and antenna feed point.  I
would also consider radials off the roof to lengthen the ground plane as
much as possible.  If they cannot follow the slope of the roof, then
consider running them down the sides of the house and then across your
yard/garden areas.  this solution assumes you have no interest in 80 or 40
meters with this antenna.  I can give you multi-band suggestions if you want
to consider a 40 meter trap at the top of the mast and/or 80 meter traps in
the top loading wires.

73    George    K8GG





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