Not to overdo my posting privilege, but I have something that might be
of interest for sale: An old Johnson 275-watt Matchbox, which is a
link-coupled balanced tuner for 80-10 meters (although WARC bands do not
appear on the bandswitch, it usually works on 30-17-12 when set to an
adjacent
On Thu, May 15, 2014 at 8:58 AM, Vic Rosenthal K2VCO k2vco@gmail.comwrote:
Not to overdo my posting privilege, but I have something that might be of
interest for sale: An old Johnson 275-watt Matchbox, which is a
link-coupled balanced tuner for 80-10 meters (although WARC bands do not
David,
I have enjoyed the dialog on this subject immensly as it reminds me of the
jouney I travelled to opitmize my wire antenna. The two major sources I have
studied include www.dxengineering (their articles on baluns and coax losses in
multiband antenna installations are excellent) and
A very interesting read, I have a couple of questions about practical
considerations.
The number one rule I look at all antennas with, is that all antennas
are a compromise. Let me know if I am getting off on the wrong foot here.
I like ladder line fed to various antennas (Horiz. Loops,
David,
The Wireman has a lightning arrestor for use with ladder line - it looks
very much like a pair of spark plugs mounted on a piece of copper. It
does not ground the ladder line, but it does provide suppression for
lightning surge voltages.
You may have better luck with a 1:1 balun
David, Industrial Communications Engineers (I.C.E.) makes a couple of open
wire arrestors that I think are well designed. On both legs of the open
wire they feature a DC short to ground (inductor) on the antenna side that
helps drain static ( and resulting noise) from the antenna, a gas tube to
Chuck - AE4CW wrote:
David, Industrial Communications Engineers (I.C.E.) makes a couple of open
wire arrestors that I think are well designed. On both legs of the open
wire they feature a DC short to ground (inductor) on the antenna side that
helps drain static ( and resulting noise) from the
That's important!
ICE says that they will work with impedances of 300-600
ohms. Although the characteristic impedance of a line may
be within this range, the impedance *seen* at a particular
point could be very high or low.
Multiply line SWR by line impedance. Most ladder line is
around
Tom W8JI wrote:
It takes exactly the same common mode impedance and common mode current
and voltage capacity in the balun if it is located at the tuner output
or at the tuner input when the network is a floating unbalanced
Probably true of the 1:1 configuration, but not of the 1:4
Probably true of the 1:1 configuration, but not of the 1:4
configuration. If you analyze the latter in terms of
chokes, you have a choke connected across the differential
signal, so if the differential impedance is high, most of
the current would bypass the antenna.
Why would anyone ever
Tom W8JI wrote:
Why would anyone ever put a 4:1 voltage balun on a tuner input? Bad
enough to use one on the output!
Who said voltage balun? The Elecraft 4:1 baluns are current baluns.
One wouldn't put them directly on the input, but the point was that it
is not sufficient to say that a
David Woolley wrote on Sunday, August 17, 2008 at 1:02 PM
Actually one might put them on the input, in the sense that one might have
a balanced feeder at close to 200 ohms and a balanced tuner at the antenna
end. That's probably the only case in which they would work well. (Given
that good
Actually one might put them on the input, in the sense
that one might
have a balanced feeder at close to 200 ohms and a balanced
tuner at the antenna end. That's probably the only case
in which they would work well.
The basic rule still applies. We can't move any balun to the
input of an
Tom W8JI wrote:
The only time moving the balun helps is if the network is a balanced
network. Even your example shows with the 4:1 balun you still had to use
Agreed. I had overlooked feed point tuner needs to balanced in that case.
a balanced tuner. With an unbalanced tuner the feedline
The question is, what is good enough? To minimize radiation from an open
wire tuned feeder requires, I believe, that the currents in the two wires to
be equal in magnitude and have a phase difference of 180 degrees at the
feedpoint of the feedline. Feeding a slanted dipole, which is certainly
Also, the load has a huge effect on balance. Few wire antennas for HF offer
decently balanced loads. Unless the wires are literally wavelengths (usually
hundreds of feet) from the earth and other objects, those objects will have
a strong effect on the currents on each side of the antenna. The
I heard some one say that a balanced tuner is very expensive to build. I used
some quarter inch copper tubing from the hardware store to build a four inch
coil. This is the tubing for a ice maker. I then built a four inch coil and
tapped it to a multi position switch from radio shack. I had a
I heard some one say that a balanced tuner is very
expensive to build. I used some quarter inch copper tubing
from the hardware store to build a four inch coil. This is
the tubing for a ice maker. I then built a four inch coil
and tapped it to a multi position switch from radio shack.
I had
On Sat, 16 Aug 2008 11:22:52 -0400, Tom W8JI wrote:
Moving the balun to the input of an unbalanced network does
NOT make life on the balun or the system easier for the
truly difficult problem, common mode isolation.
I strongly agree with all of this. One of the most important
functions of a
How about a normal L-type network? Connect one side to the balanced
line, and the other side via a current balun to the 50 coax. The tuner
is 'RF-floating'. (You can run the coax through a toroid or use two
seperate wires to make the current balun.)
73,
Arie PA3a
How about a normal L-type network? Connect one side to the balanced line,
and the other side via a current balun to the 50 coax. The tuner is
'RF-floating'. (You can run the coax through a toroid or use two seperate
wires to make the current balun.)
73,
Arie PA3a
How about a normal L-type network? Connect one side to the
balanced
line, and the other side via a current balun to the 50
coax. The tuner
is 'RF-floating'. (You can run the coax through a toroid
or use two
seperate wires to make the current balun.)
Arie,
Respectfully that does not work at
Arie,
An L network with the inductor in series with the line can be easily
made into a balanced tuner - use half the inductance and put the result
in series with each leg of the load. I have often thought about
creating a tuner like that by altering a KAT100 (using a second board
and set of
So, Tom, how would you comment upon a transistorised rig of 50 ohms
impedance unbalanced output connected to an unbalanced pi configuration
antenna coupling unit (variable C1 between input and ground, variable
series L in the hot lead, and variable C2 between output and ground)
followed by a
So, Tom, how would you comment upon a transistorised rig
of 50 ohms impedance unbalanced output connected to an
unbalanced pi configuration antenna coupling unit
(variable C1 between input and ground, variable series L
in the hot lead, and variable C2 between output and
ground) followed by a
Tom, thanks for this.
Actually, I do not think it OT. My KAT100 is an unbalanced coupling
unit, and my antenna is as described, so I am looking to match it
properly! At present I have a 4:1 balun (relieved from duty at the font
end of an HF LPDA) connecting the 450 ohm feeder to a short
since i just run qrp i have an elecraft t-1 remoted 60ft from my shack at
the base of an oak tree at the midpoint of my dipole.
a simple injection circuit provides for remote tune activation.
73
jim ab3cv
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Post to:
forgot to add that i'm using a ferrite choke on the input of the t-1 current
on the outside of the coax which is buried all the way back to the house.
tunes 80m to 10m, need to try it on 6m now that i have a k3.
73
jim ab3cv
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Tuner efficiency question
I've spent many years testing and evaluating tuner designs.
Using the Ten Tec 2KW L tuner, the Nye Viking 5KW MBV, the Johnson
KW Matchbox and home brew T network tuners. As well as my own
designs for a number of different types of dual balanced line tuners.
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