Jim Kelley wrote:
Can you describe the balun you used?

When one feeds the antenna system at a current maximum
point, the balun is non-critical. I am presently using
ten turns of RG-400 on an FT-240-61 toroid with no
measurable common mode current on an MFJ-853. As you
know, the stress on the balun is reduced when the
resonant current maximum point is located at the
output of the balun-choke. That's another bonus for
the matching system that I use.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
When one feeds the antenna system at a current maximum
point, the balun is non-critical. I am presently using
ten turns of RG-400 on an FT-240-61 toroid with no

Hi Cecil,
It seems like it's been a decade since we debated on RRAP. I hope all is
well with you.

I plan on erecting a multi-band inverted V with several insulators and
associated shorting connectors along each leg so that with all connectors
open, the antenna is resonant on 10m; with the first insulator on each leg
shorted, the antenna is resonant on 15m; with the first and second insulators
on each leg shorted the antenna is resonant on 20m; et cetera. Shorting and
opening insulators is easier than winding accurate chokes!

For a balun, I'm considering N4UJW's "Ugly Balun"
(see http://www.hamuniverse.com/balun.html).
UJW leaves the diameter of the coil form to the reader, only specifying that
18-21 feet of coax be used. Can you (or anyone else on RRAA) tell me if there
is an optimum diameter, considering that most of my operations will be on 20m?
(On that page, UJW has two balun projects -- see the first one.)

Warmest regards,
Jeff KH6O

Chief Petty Officer, U.S. Coast Guard
Mathematics Lecturer, University of Hawaii System
--

Jeffrey Herman wrote:
Hi Cecil,
It seems like it's been a decade since we debated on RRAP. I hope all is
well with you.

Things are terrible. I can't dunk a basketball anymore. :-)
Good to hear from you.

For a balun, I'm considering N4UJW's "Ugly Balun"
(see http://www.hamuniverse.com/balun.html).
UJW leaves the diameter of the coil form to the reader, only specifying that
18-21 feet of coax be used. Can you (or anyone else on RRAA) tell me if there
is an optimum diameter, considering that most of my operations will be on 20m?

This subject was recently beat to death over on QRZ.com or
eHam.net, I can't remember which. Here's some actual
measurements showing how the choking impedance varies
with frequency:

http://www.k1ttt.net/technote/airbalun.html

An ugly balun (N turns of coax) will not cover a 10:1
frequency range very well. If it performs well on 10m,
it doesn't have very much choking impedance on 80m. If
it performs well on 80m, it will have reached its series
resonant low impedance point before it reaches 10m. An
ugly balun performs reasonably well over a 3:1 frequency
range. And the choking problem worsens considerably with
non-resonant antenna systems.

However, the necessary choking impedance is minimized
if the antenna is low impedance resonant as yours will
be. I made some measurements on 20 turns of coax on a
2 liter pop bottle. It was parallel resonant at 14 MHz
(good high impedance) and series resonant at 28 MHz
(bad low impedance). It would probably function pretty
well from 40m to 15m.

A toroidal 1:1 choke-balun is much more broadbanded than
an ugly balun. For your antenna, ten turns of RG-400 on
a FT-240-61 toroid would, like mine, be good enough.
The AB-240-kit contains that toroid and comes with
instructions for winding a 1:1 choke-balun, all for $9.
However, I would not recommend that balun for non-
resonant antenna systems where three of those toroids
stacked would be about right. That web page is at:

http://www.amidoncorp.com/aai_cost_experimenter.htm
--
73, Cecil http://www.w5dxp.com

"Jeffrey Herman" wrote in message
...
Cecil Moore wrote:
When one feeds the antenna system at a current maximum
point, the balun is non-critical. I am presently using
ten turns of RG-400 on an FT-240-61 toroid with no

Hi Cecil,
It seems like it's been a decade since we debated on RRAP. I hope all is
well with you.

I plan on erecting a multi-band inverted V with several insulators and
associated shorting connectors along each leg so that with all connectors
open, the antenna is resonant on 10m; with the first insulator on each leg
shorted, the antenna is resonant on 15m; with the first and second
insulators
on each leg shorted the antenna is resonant on 20m; et cetera. Shorting
and
opening insulators is easier than winding accurate chokes!

For a balun, I'm considering N4UJW's "Ugly Balun"
(see http://www.hamuniverse.com/balun.html).
UJW leaves the diameter of the coil form to the reader, only specifying
that
18-21 feet of coax be used. Can you (or anyone else on RRAA) tell me if
there
is an optimum diameter, considering that most of my operations will be on
20m?
(On that page, UJW has two balun projects -- see the first one.)

Warmest regards,
Jeff KH6O

Chief Petty Officer, U.S. Coast Guard
Mathematics Lecturer, University of Hawaii System
--
How do you plan on actuating the switches? I tried some knife swithes and
thought I could switch them using a hook on a pole. This didnt work very
well for an all band antenna.

Jimmie D wrote:
How do you plan on actuating the switches? I tried some knife swithes and
thought I could switch them using a hook on a pole. This didnt work very
well for an all band antenna.

When I was in high school, I built my dipole with
a pulley at each end. For changing bands, I just let
the dipole down and either installed or removed the
jumper wires across the insulators. An Inv-V would
only require one pulley.
--
73, Cecil http://www.w5dxp.com

"Cecil Moore" wrote in message
et...
Jimmie D wrote:
How do you plan on actuating the switches? I tried some knife swithes and
thought I could switch them using a hook on a pole. This didnt work very
well for an all band antenna.

When I was in high school, I built my dipole with
a pulley at each end. For changing bands, I just let
the dipole down and either installed or removed the
jumper wires across the insulators. An Inv-V would
only require one pulley.
--
73, Cecil http://www.w5dxp.com

Yeah I thought about this but was trying to stay away from raising and
lowering the antenna. I used to have the antenna on a pulley but found that
sometimes the neighbor kids would lower it for me. The ones who were doing
it arent around anymore so I guess its safe to put it back up now.

On Sat, 6 Jan 2007 11:31:45 -0500, "Jimmie D"
wrote:

The ones who were doing it arent around anymore

Hi Jimmie,

Is it possible you had the key down when they last tried lowering it?

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Sat, 6 Jan 2007 11:31:45 -0500, "Jimmie D"
wrote:

The ones who were doing it arent around anymore

Hi Jimmie,

Is it possible you had the key down when they last tried lowering it?

73's
Richard Clark, KB7QHC

No, they were reallly good kids over all, they didnt get into half as much
as I did when they were my age. At least I dont think they ever fished with
pipe bombs. They also kept my grass cut while I was away for a really
reasonable price.

Jimmie D wrote:
Yeah I thought about this but was trying to stay away from raising and
lowering the antenna. I used to have the antenna on a pulley but found that
sometimes the neighbor kids would lower it for me. The ones who were doing
it arent around anymore so I guess its safe to put it back up now.

Them "not being around anymore" could mean any number
of things. :-)
--
73, Cecil http://www.w5dxp.com

I hate when kids mess with my antenna stuff!