"billcalley" wrote in message
oups.com...
What I gleaned from the excellent answers for the original "VSWR
Doesn't Matter?" thread is that high VSWR doesn't really matter in a
lossless transmission line environment between a transmitter's antenna
tuner and the antenna, since any reflected RF energy will simply
continue to "bounce" back and forth between the tuner's output
impedance and the antenna's input impedance until it is, finally,
completely radiated from the antenna without loss.

That's basically true but ignores the stress that can be placed on the
output circuit of the transmitter. Why do you think VSWR shut-down circuits
are so popular? One can see rather high voltages or currents that are
potentially damaging to the transistors and capacitors.

Now, since "lossless" is an abstraction and all materials have voltage and
current limits, just make this easy on yourself and always strive for a VSWR
of 2:1 or less. It simply works better and is more reliable.

Charles Schuler wrote:
Now, since "lossless" is an abstraction and all materials have voltage and
current limits, just make this easy on yourself and always strive for a VSWR
of 2:1 or less. It simply works better and is more reliable.

But renders many all-HF-band dipoles useless. :-) I regularly
run up to an 18:1 SWR on my 450 ohm ladder-line. Owen's
transmission line calculator says I'm losing about 0.8 dB
in 100' of line under those conditions on 40m. IMO, it's
a small price to pay for all-HF-band operation.
--
73, Cecil, w5dxp.com

"Cecil Moore" wrote in message
...
Charles Schuler wrote:
Now, since "lossless" is an abstraction and all materials have voltage
and current limits, just make this easy on yourself and always strive for
a VSWR of 2:1 or less. It simply works better and is more reliable.

But renders many all-HF-band dipoles useless. :-) I regularly
run up to an 18:1 SWR on my 450 ohm ladder-line. Owen's
transmission line calculator says I'm losing about 0.8 dB
in 100' of line under those conditions on 40m. IMO, it's
a small price to pay for all-HF-band operation.

How many Ham transmitters have a balanced output?

How are you feeding a balanced line?

If you are using an antenna tuner with unbalanced in (50 ohms) and balanced
out (variable impedance), you should be OK in most situations.

Charles Schuler wrote:
How are you feeding a balanced line?

http://www.w5dxp.com/notuner.htm

If you are using an antenna tuner with unbalanced in (50 ohms) and balanced
out (variable impedance), you should be OK in most situations.

No tuner! I don't like tuner losses. The feedpoint impedance
is always between 35 ohms and 85 ohms resistive. My choke
has an impedance in the thousands of ohms.
--
73, Cecil http://www.w5dxp.com

On Thu, 29 Mar 2007 22:44:24 GMT, Cecil Moore
wrote:

No tuner! I don't like tuner losses. The feedpoint impedance
is always between 35 ohms and 85 ohms resistive. My choke
has an impedance in the thousands of ohms.

Cecil,

Please explain your antenna and radio. I am assuming you have a solid
state rig with an so-239 connector on it for the basic and then you do
what?

Thanks


--
73 for now
Buck, N4PGW
www.lumpuckeroo.com

Buck wrote:
Cecil Moore wrote:
Please explain your antenna and radio. I am assuming you have a solid
state rig with an so-239 connector on it for the basic and then you do
what?

Hi Buck, Please check out my associated web page and then
ask me anything that you don't understand.

http://www.w5dxp.com/notuner.htm

Contrary to what you may have been told, you can change
the 50 ohm SWR seen by your transmitter by changing the
length of the 450 ohm ladder-line.
--
73, Cecil http://www.w5dxp.com

On Fri, 30 Mar 2007 02:43:38 GMT, Cecil Moore
wrote:

Buck wrote:
Cecil Moore wrote:
Please explain your antenna and radio. I am assuming you have a solid
state rig with an so-239 connector on it for the basic and then you do
what?

Hi Buck, Please check out my associated web page and then
ask me anything that you don't understand.

http://www.w5dxp.com/notuner.htm

Contrary to what you may have been told, you can change
the 50 ohm SWR seen by your transmitter by changing the
length of the 450 ohm ladder-line.

Ok, I have seen that. It isn't that the antenna isn't tuned, it is
tuned with the twin-lead instead of a conventional tuner.

I might have enough twin lead to build one of those. I'll have to
consider it. It has always tweaked my interest.

Thanks



--
73 for now
Buck, N4PGW
www.lumpuckeroo.com

Cecil Moore wrote:

Buck wrote:
Cecil Moore wrote:
Please explain your antenna and radio. I am assuming you have a solid
state rig with an so-239 connector on it for the basic and then you do
what?

Hi Buck, Please check out my associated web page and then
ask me anything that you don't understand.

http://www.w5dxp.com/notuner.htm

Contrary to what you may have been told, you can change
the 50 ohm SWR seen by your transmitter by changing the
length of the 450 ohm ladder-line.
Now that is a "real" ham radio antenna system, screwampus but it provably
works, and is repeatable (by others).
--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.Â*Â*
--Schiller

http://www.w5dxp.com/notuner.htm

Cecil,

Looking more at your antenna, I am making several observations. I
posted the URL at the top for other readers to know what we are
talking about.

I kind of wish you would change the name of the antenna and not call
it 'no-tuner' because I feel let down every time I look at it and see
the feed-line tuner. I realize it isn't a conventional tuner. Don't
get me wrong, I think it is a GREAT idea and I like it very much and
would like to try it myself. However, I feel it is a little deceptive
in the name.

I have a few questions about the system. I may have asked some
already in another thread, so please bear with me. This is a better
place to discuss it rather than hijacking another thread.

I see you use 450 ohm ladder line (or window-line as some call it.) I
am wondering if the concept will also work with other impedance
feedline such as 600, 300 or 75 ohm twin-line or even possibly with
coax. ****


**** I just looked over your program. I see that you have it setup to
allow 300 or 450 ohm ladder line. I wonder if you have LLWL available
for 600 and 75 ohm.... I will try to put this in XL. (I don't have a
basic program.) OK, I just found the compiled program.

I am interested in making one, but I only have 300 ohm.

Does the feedline act as part of the antenna? I am sure it will, at
least up to the 'no-tuner' if it acts like a G5RV, but do you know if
the feedline radiates?

Have you measured the power at both sides of the 'no-tuner' to see
what loss there might be? I doubt there would be much considering
that you are using window-line.

I see a couple of the frequencies are above 1.5:1, which I am not
comfortable going over with solid state rigs. Do you think that could
be fine-tuned with the addition of a 1/2 foot section or maybe with
that and a 1/4 foot section?

Would it be safe to assume that I can create a mono-band dipole, maybe
even multi-band - if I am lucky, by fixing the length of the dipole
and the feedline such that the increment gives me the imax at the
balun for the desired frequency(s)?

Finally, you have a 1:1 choke at the feeder. I see that the better
quality coax, the more toroids are needed. Would there be a problem
with using a foot of RG-58 with the fewer toroids and then connect
that to the high-quality line? I suspect that by then the common-mode
currents will be gone and there would be minimum loss in such a short
strand of lower-grade coax for HF. I doubt there would be a
noticeable signal loss.

Does the 'no-tuner' feedline need to be spread out. I see from the
photo that your 16 foot section is one large loop, I figure it must be
close to a four-foot diameter loop.

Is there a similar system that would work with a vertical?

Thank you,

I appreciate your taking time to answer this. I hope many of us can
learn from it.

Buck
N4PGW








--
73 for now
Buck, N4PGW
www.lumpuckeroo.com

After reading your webpage more closely......

On Fri, 30 Mar 2007 10:42:26 -0400, Buck
wrote:


http://www.w5dxp.com/notuner.htm

I see you use 450 ohm ladder line (or window-line as some call it.) I
am wondering if the concept will also work with other impedance
feedline such as 600, 300 or 75 ohm twin-line or even possibly with
coax. ****

Does the feedline act as part of the antenna? I am sure it will, at
least up to the 'no-tuner' if it acts like a G5RV, but do you know if
the feedline radiates?

That answer would be 'no'. I see that the purpose of the feedline
length is to get the maximum current at the center point of the
dipole.




I see a couple of the frequencies are above 1.5:1, which I am not
comfortable going over with solid state rigs. Do you think that could
be fine-tuned with the addition of a 1/2 foot section or maybe with
that and a 1/4 foot section?

Based on the fact that the antenna is being fed maximum current at the
center, I would guess that this should work.





Buck
N4PGW

--
73 for now
Buck, N4PGW
www.lumpuckeroo.com