[Antennas] 2 trees 150' apart 60' high

Thu Jun 2 18:02:54 EDT 2005

> The last time I looked the formula for a 1/2 wl dipole was
> 468/Feq in MHz. 468/3.75 = 124.8 ft.
>> 73 de Jerry, KØEJF
> E.J.(Jerry) Forwood

Jerry - I read 75m and "saw" 40, LOL. Thanks.
Jack
> -- "Jack Painter" <223bthp at cox.net> wrote:
> Larry wrote:
> > I have 2 pin trees about 150' apart and about 60' tall, about 200 feet
> > of #10 insulated stranded wire and 100' of 450 Ohm ladder line. My
> > tuner has a balanced line input and I also have a 1:1 balun handy. I
> > also have 50 and 75 Ohm coax cable.
> >
> > I am looking for all band operation, but with the way bands are now I
> > probably should concentrate on 75-20 Meters.
> >
> > My thought is 150' dipole fed by ladder line to the tuner is the best
> > use of the space.
> > Would a 125' 75 Meter dipole with the balun at the feed point and coax
> > feed be a better choice?
> > I had a G5RV up for many years but one leg broke about a foot from an
> > end insulator, should I just fix/shorten that antenna and put it back
> > up?
> >
> > Any ideas?
>> Larry,
>> That's a long span to support a dipole, but possible. I have a
> 60 meter and
> 75 meter (fan) center-coax-fed dipole with 1:1 current-type balun at the
> feedpoint. My span is 115', and dipole length for 60 meters is about 90'.
> Your 75 meter dipole would not be anywhere near 125' long, so
> I'm, not sure
> where you came up with the 125' number.
>> Feeding with ladder-line might help you (with a tuner) for some all-band
> capabilities. With at least 1/4 WL elevation, the dipole is an outstanding
> performer on it's cut frequency bands. This performance drops off
> the higher
> in frequency you use it, until still workable but not a good
> performer much
> above 20 meters. You can use both standing and running rigging and blocks
> (pulleys) to support the heavy Balun and antenna lines. 5/16th or heavier
> milspec Dacron (standing rigging to hold the Balun) and lighter lines
> (running rigging) to raise and lower the antennas for trimming/tuning.
>> Be sure to well waterproof and strain-relief the coax connector under the
> Balun (if used), and allow for opposite wind/sway of the pine trees by not
> pulling the support lines or antennas too taut. Mine survived a
> hurricane,
> but that means those two pine trees also made it, many did not!
>> Best regards,
>> Jack
> Virginia Beach, Virginia
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