Buck wrote:
This is the antenna I want to copy before I start experimenting:
http://hamcall.net/6bandmegpole.html

Hi Buck, they don't give exact building information as far
as I can tell. Here's what they say: Inverted V with the
center at 32 ft and ends at 8 ft. Approximately 135 ft
long fed with 100 ft of RG-213.

Why 32 ft with the ends at 8 ft? Because that is the
configuration that gives the advertised values of SWR.
Why 100 ft of RG-213? Because the losses in the coax
results in the advertised values of SWR. If you deviate
from their configuration including having different
ground conditions, you will, no doubt, need an antenna
tuner for some bands. They have probably fine tuned their
configuration so they can make their claims which you
probably will not be able to duplicate. I don't want to
discourage your experimentation - just make a prediction
based on experience.

If you really want an efficient all-eight-HF-band antenna
requiring no tuner, you can find one on my web page at
http://www.qsl.net/w5dxp/notuner.htm
If you don't want to go to the trouble of varying the
length of your feedline, you can at least learn what
you are up against in your quest.
--
73, Cecil http://www.qsl.net/w5dxp


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On Mon, 31 Jan 2005 08:42:30 -0600, Cecil Moore
wrote:

Buck wrote:
This is the antenna I want to copy before I start experimenting:
http://hamcall.net/6bandmegpole.html

Hi Buck, they don't give exact building information as far
as I can tell. Here's what they say: Inverted V with the
center at 32 ft and ends at 8 ft. Approximately 135 ft
long fed with 100 ft of RG-213.

Why 32 ft with the ends at 8 ft? Because that is the
configuration that gives the advertised values of SWR.
Why 100 ft of RG-213? Because the losses in the coax
results in the advertised values of SWR. If you deviate
from their configuration including having different
ground conditions, you will, no doubt, need an antenna
tuner for some bands. They have probably fine tuned their
configuration so they can make their claims which you
probably will not be able to duplicate. I don't want to
discourage your experimentation - just make a prediction
based on experience.

If you really want an efficient all-eight-HF-band antenna
requiring no tuner, you can find one on my web page at
http://www.qsl.net/w5dxp/notuner.htm
If you don't want to go to the trouble of varying the
length of your feedline, you can at least learn what
you are up against in your quest.


thanks, Cecil.

I have looked at that before.

( Not to argue with you, but I considered your feedline switches a
form of tuner, just not conventional .

That is definitely a great looking antenna. I am glad you pointed out
the precision needed on the OCF I was looking at. What I am working
towards is a great all-band antenna that can be easily ported and
setup and used without switching (kind of like the T2FD) and no
unique parts required.

I am glad to meet you (and know who you are.) To be honest, I have
spent a lot of time on your site. At one time, I could have answered
many questions about your antenna without looking at it. Your site is
the first place I saw the ferrite beads on the feedline for a choke
and I have investigated them in depth since then too.

One thing I didn't find about the antenna was the bandwidth of 40/80
meters or an SWR chart for each band. (I realize that you might not be
able to do that easily, I'm just stating an observation.)

Also, in addition to the antenna I mentioned to you (It was only one
of several OCF's I am looking at), it seems to be common for OCF
antennas to use 6:1 baluns. Some do use 4:1 and most, regardless of
the balun, require a tuner.

I have several ideas that I am kicking around so being able to easily
be able to build an inexpensive balun at different ratios will come in
very handy for my experiments.

Before the internet there were books. The best one could hope for was
to see a picture of the author on the cover, but now, after all these
years, I am still amazed when I find myself in conversation what use
to be ... the untouchables.

It was great to meet you. Thanks for replying.

Buck.


--
73 for now
Buck
N4PGW

Buck wrote:
( Not to argue with you, but I considered your feedline switches a
form of tuner, just not conventional .

More precisely, a form of tuned feeders.

One thing I didn't find about the antenna was the bandwidth of 40/80
meters or an SWR chart for each band. (I realize that you might not be
able to do that easily, I'm just stating an observation.)

The HF bandwidth of that antenna *plus* the tuned feeders is 27
MHz, all the way from 3 to 30 MHz with an SWR of less than 2:1
(for the ham bands). I haven't measured the SWR outside of the
ham bands. There's a graphic that shows the SWR=2:1 bandwidth
for 40m to be about 160 kHz for a fixed length of ladder-line.
--
73, Cecil http://www.qsl.net/w5dxp


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On Mon, 31 Jan 2005 12:24:20 -0600, Cecil Moore
wrote:

Buck wrote:
( Not to argue with you, but I considered your feedline switches a
form of tuner, just not conventional .

More precisely, a form of tuned feeders.

One thing I didn't find about the antenna was the bandwidth of 40/80
meters or an SWR chart for each band. (I realize that you might not be
able to do that easily, I'm just stating an observation.)

The HF bandwidth of that antenna *plus* the tuned feeders is 27
MHz, all the way from 3 to 30 MHz with an SWR of less than 2:1
(for the ham bands). I haven't measured the SWR outside of the
ham bands. There's a graphic that shows the SWR=2:1 bandwidth
for 40m to be about 160 kHz for a fixed length of ladder-line.


how much RF is in the shack when you use your system?


--
73 for now
Buck
N4PGW

Buck wrote:

Cecil Moore wrote:
The HF bandwidth of that antenna *plus* the tuned feeders is 27
MHz, all the way from 3 to 30 MHz with an SWR of less than 2:1
(for the ham bands). I haven't measured the SWR outside of the
ham bands. There's a graphic that shows the SWR=2:1 bandwidth
for 40m to be about 160 kHz for a fixed length of ladder-line.

how much RF is in the shack when you use your system?

The ladder-line comes off at right angles to the balanced
dipole so common-mode current is minimum and is choked
on the transmitter side of the ladder-line length selector.

Balanced currents don't cause "RF in the shack". If the
currents are unbalanced, RF in the shack is likely with
either coax or balanced line.
--
73, Cecil http://www.qsl.net/w5dxp


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