Cecil Moore wrote:


Here's a simple statement he could have made about reflected
power not being lost:

In a conjugately matched system using lossless transmission line:

Source Power = Forward Power - Reflected Power = Load Power

Let's face it Cecil, that man was obviously "being paid by the word"--in
our capitalistic society--I can understand that! (However, this paper
appears to have been done to "justify" "his antennas" which he was
selling at the time. Indeed, it reminds me, very much, of how db has
been abused ... I'd say, in this regard, he did a nice job of
"Barnum-ing it!" And, was wholly motivated by financial gains. LOL )

And, in that "reality", 100 words are worth 10x as much as 10 words ...
and, any inaccuracy will just be justification for more words (and more
profit) on another day ... or, more obsfucation ...

Regards,
JS

Howard Kowall wrote:
Looking to buy a G5RV for 80 and 40 mtrs and maybe able to tune other bands
lots of diff brands of this antenna
can anyone suggest a manufacture
or maybe another alternative
thanx
howard


Howard,

I made a homebrew using ARRL information and some advice from this
group...pretty inexpensive and it continues to work well after 2 yrs.
With a decent ATU, you should get most bands. Mine won't tune 30M. My
G5RV is cut for 40M but does fairly well on 80M also. There is a longer
version cut for 80M. Mine is copper wire, 300 Ohm window line for the
feed and no balun. This comports with the original design, I think.

You can buy center and end insulators from many suppliers, including DX
Engineering (or just make your own: short pieces of PVC, for eg...spray
painted blk for UV protection).

One thing I might add to my G5RV (after listening to this group) would
be some ferrite beads on the coax at the end of the measured window line
feed.

For me, Building is more fun than Buying.

Good luck and 73

John
AB8O

Jim Higgins wrote in
:

....
Which "RG-8" is the author referring to? Belden 8237, Belden 8267 or
Belden 9913? His cited loss figures are way too low for Belden 8267
(RG-213), probably the most common coax in use by hams on HF and high
for Belden 9913, a spiral wound largely air dielectric coax that's a
bitch to keep dry in outdoor use. He only cites the loss at 4MHz.
Loss at 14 MHz is almost 3dB and at 28 MHz exceeds it. I'll fix the
antenna before I'll use a tuner to fool the transmitter.

When they does get down to some hard numbers they can be wanting. Re your
example above, they say "Since a 10:1 swr on 100 feet of RG8U at 4 Mhz
increases loss by less than 1 db, don't worry...". The loss on 100' of
RG8/U at 4MHz with a 50+j0 ohm load is 0.35dB, the loss with a 5+j0 ohm
load is 1.64dB (a bad case of load end VSWR=10), some 1.3dB higher and
clearly not less than 1dB higher as he explains. Since it is not clear,
some readers might even think that the statements apply to indicated VSWR
at the source end of the line.

When they get some things that are easy to check quite wrong, it does
cast doubt on the credibility of the paper. Their point in this case
about band edge VSWR is probably fair if qualified for usual
configurations... but it needs qualfication and the premise they use to
support the assertion is plain wrong. Why didn't they just correctly
state the increased loss at VSWR=2 in support of their argument (it is
about 0.1dB)?

You could pick through the technical content of the paper in this way,
and try to discover if there is any real value to the name dropping...
but it is a mix of good stuff and not so good stuff. There is still a
place in the world for text books.

Nevertheless, I sympathise with them trying to find good reviewers... it
is a challenge.

Owen

In article , Cecil Moore
wrote:

John Smith wrote:
If you can't make a SIMPLE statement (or paper), on a concept, which an
average layman can understand, you probably don't understand the
concept(s) yourself ... end of story.

Here's a simple statement he could have made about reflected
power not being lost:

In a conjugately matched system using lossless transmission line:

Source Power = Forward Power - Reflected Power = Load Power

Hello, and in a general case one has to be careful in dealing with the
concepts of "forward" and "reflected" when talking about power. It can
become an issue when source impedance, tranmission line characteristic
impedance, and load impedance all have different values. The "matched"
value corresponding to no reflections might not be the value for maximum
power transfer from source to load. In this general case incident
(forward) voltage or current from the source becomes a function of
mismatch between the source and the reference impedance (e.g. 50 ohms) and
the mismatch between the load and reference. When the source is matched
this dependency vanishes and the incident power is the same as the
"available" power (Vsource^2/(4 * Real part of source impedance)) from the
source.

The source can be "matched" to the input of the transmission line feeding
the load but not be conjugately matched to the transmission line/load
combination.
Conversely, we can have reflections present at the source-line interface
for conjugate match conditions. Sincerely, and 73s from N4GGO,

John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

J. B. Wood wrote:
Cecil Moore wrote:
In a conjugately matched system using lossless transmission line:
Source Power = Forward Power - Reflected Power = Load Power

The source can be "matched" to the input of the transmission line feeding
the load but not be conjugately matched to the transmission line/load
combination.

Note that I specified an ideal lossless transmission line.
In a lossless system, if a conjugate match exists anywhere,
a conjugate match exists everywhere. My assertion was a
conceptual statement about an ideal example.

Conversely, we can have reflections present at the source-line interface
for conjugate match conditions.

I was also assuming a 50 ohm source with a 50 ohm Z0-match in a
lossless system. I should have specified such. Here is what I
had in mind.

XMTR---50 ohm coax---+---1/8WL 300 ohm twinlead---(97.3-j283.8)

There is a (close enough) 50 ohm Z0-match at '+' :-)
--
73, Cecil http://www.w5dxp.com
"According to the general theory of relativity,
space without ether is unthinkable." Albert Einstein

Cecil Moore wrote:

...
Note that I specified an ideal lossless transmission line.
In a lossless system, if a conjugate match exists anywhere,
a conjugate match exists everywhere. My assertion was a
conceptual statement about an ideal example.
...


Cecil:

I believe so ...

However, you have been lifting weights with your brain. These things
look elementary to you; your only mistake is you do not strive for even
a simpler example, to let those wishing to, catch that first step ...

The lossless line is a key. Remember those lines of force around a
magnet which can be seen with some iron powder and a paper?

These are being stored within the ether; you are seeing the only feeble
proof of the ethers existence--magnetic lines of force, in that simple
experiment. Remember the plans to store energy in a superconductor
configured in an endless loop? Where do people think that energy is
being stored? In the electrons and other particles? Naaa ... it is
being stored within the ether--in magnetic lines of force ...

You lossless line has no loss, simple. 100% of the power being stored
in the ether is being gotten back from the ether (and your lossless line
is a superconductor.) And, when that condition exists, the workings of
the antenna become a bit more clear (visible) ...

Art says some of this in his "ramblings", most just don't look for it
.... Art just obsfucates beyond recognition (or fubar!)

Regards,
JS