Thread: Antenna Tuner
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Old December 13th 04, 08:45 PM
Jack Painter
 
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wrote
Yes, thank you..I have been thinking about modifying an existing tuner
with the balun on the output. The problem is that ALL components must
be isolated from ground. I suppose I could pull that off, but it is
not as simple as you might think, especially with a tuner that uses a
tapped inductor in a T match. I t would probably be easier to float a
roller inductor than a tapped inductor because of the switch. The
caps are usually above ground already in a T match, so thats not a
problem. I'm thinking about it, but it would be nice if there was a
good affordable balanced tuner out there.
Jim


Jim, your original query and subsequent comments leave a couple of
questions:

1. Is an ATU desired?
2. Will it operate a balanced line? (other antennas as well?)
3. Why is isolation from ground so important to you?

Radio Works puts out some good products, one of them is the Line Isolator
for just the situation you are possibly describing:

http://www.radioworks.com/PDFLineIsolator.htm

However it should be noted that this is offered by Radio Works (in my
opinion) mainly because they promote the Carolina Windom style antennas,
which are designed to radiate vertical components of feedline. Most antenna
types, especially anything using a Balun at the feedpoint would have no such
radiation on the feedline or shield. Antennas requiring good RF ground or
radials would do so, those that don't still require bonding and grounding
for lightning protection, at least in any area that can have lightning. So
the multiple use of line isolators, and/or your insistence on having all
components isolated from ground may correct RF problems that should be
addressed at their cause, and at the expense of maintaining safe bonding and
grounding of the station equipment for lightning protection.

As Bob Miller also added (fwiw): I use two MFJ tuners, the 962D 1.5kw
air-core inductor and the 994 600w ATU "Intellituner". Both perform very
well for me on end fed wires and dipoles. Isolating anything in my station
from ground is out of the question, as it should be for anyone who remains
connected to either or both power and antennas during thunderstorms.

73,
Jack Painter
Virginia Beach VA