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Old May 13th 06, 06:16 PM posted to rec.radio.amateur.antenna
 
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Cecil wrote:
This is just one more example of the dumbing down of amateur radio

accompanying the dumbing down of the US educational system in
general. Unfortunately, it seems to be a trend that cannot be
reversed because it is the biased view being pushed by the ARRL
and its supporters.


Hmmm...not sure I agree that the folks at ARRL are deliberately being
dumb (or maybe I just misunderstood you). Seems more unintentional to
me. After all, the technical editor of QEX let publish that bizarre
article that claimed to prove by math that phasing SSB receivers were
not possible. Can''t imagine a political motivation for that though I
have to wonder bigtime how that one got by. QEX really really needs
for some good peer review.

Ah, to have Ham Radio magazine back again. Loved that thing. Learned
most of my radio from it.

73,
Glenn AC7ZN

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Old May 13th 06, 06:49 PM posted to rec.radio.amateur.antenna
Yuri Blanarovich
 
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wrote in message
oups.com...
Cecil wrote:
This is just one more example of the dumbing down of amateur radio

accompanying the dumbing down of the US educational system in
general. Unfortunately, it seems to be a trend that cannot be
reversed because it is the biased view being pushed by the ARRL
and its supporters.


Hmmm...not sure I agree that the folks at ARRL are deliberately being
dumb (or maybe I just misunderstood you). Seems more unintentional to
me. After all, the technical editor of QEX let publish that bizarre
article that claimed to prove by math that phasing SSB receivers were
not possible. Can''t imagine a political motivation for that though I
have to wonder bigtime how that one got by. QEX really really needs
for some good peer review.


I don't think anyone is trying to be "deliberately being dumb", more like
"naturally being dumb" and not knowing it. :-)
Reality is that quality of technical material in ham publications is
slipping, heading for stuck on stupid. Add cheapening of ham ticket exams,
push for mass and no exam recruiting of new hams (a la CB wizards) in effort
to boost numbers and few bad apples with it - you get the picture of
deteriorating standards.

When W8JI had a presentation at Dayton's Antenna Forum and spoke about his
"famous - same current along the antenna loading coil", I came to K3LR
(forum leader) and N6BV (ARRL Antenna Book editor) and pointed out that
perhaps there is an error in W8JI assertions, I got this in private mail
from the "guru":

"When you pull people aside at Dayton to bitch about me or others or make
wild crazy statements it just makes you look worse and worse to the people
you are trying most to impress. At Dayton two years ago several people came
up and told me your tried to start conversations about me with them, or that
you started bitching about me."

Sooo, looks like one has to take some articles in ARRL publications with
biiiig grain of salt. Goofy stuff gets through, real expert material gets
swept under by "know-it-alls" in charge, Goofy is right and Right is not
important anymore. "Gurus" beat their drums into the publications and great
confusion ensues.

As far as SWR, I always tried to avoid it by matching, designing antennas to
have impedance of the feedline, and the TX/Amp output matching the feedline
impedance. Standing Wave Ratio always implied two waves - forward and
reflected and their superposition. Why waste power in "confused" standing
waves, when I can make sure that the waves are marching forward towards the
antenna and be radiated. Let the waves stand in the antenna, where they
belong, doing radiating and not in the lossy feedline.
High SWR is not imaginary, it is real, can create excessive voltages,
dielectric losses and melt the coax.

Happy Mother's Day to all the mothers that did not abort us!
God Bless them and thank you!

Yuri, da BUm


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Old May 13th 06, 07:53 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
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Yuri Blanarovich wrote:
When W8JI had a presentation at Dayton's Antenna Forum and spoke about his
"famous - same current along the antenna loading coil", ...


It is unusual for W8JI to give up on an argument so abruptly. I
wish I had thought of the dual-Z0 shortened stub concept years ago.
--
73, Cecil http://www.qsl.net/w5dxp
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Old May 13th 06, 08:17 PM posted to rec.radio.amateur.antenna
Dave
 
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tell us more, 'dual-z0 shortened stub' sounds like something interesting.

"Cecil Moore" wrote in message
. com...
Yuri Blanarovich wrote:
When W8JI had a presentation at Dayton's Antenna Forum and spoke about
his "famous - same current along the antenna loading coil", ...


It is unusual for W8JI to give up on an argument so abruptly. I
wish I had thought of the dual-Z0 shortened stub concept years ago.
--
73, Cecil http://www.qsl.net/w5dxp



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Old May 13th 06, 09:07 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
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Dave wrote:
tell us more, 'dual-z0 shortened stub' sounds like something interesting.


In my quest to explain the phase shift in a 75m bugcatcher
coil, I thought about a dual-Z0 stub. The shortest 450/50 one
I have come up with that causes the maximum phase shift is:

---19 deg of 450 ohm line---+---18 deg of 50 ohm line---open

Believe it or not, that is an electrical 1/4WL stub with a
whopping 53 degrees of *lossless* phase shift occurring at the
'+' impedance discontinuity point. Are there any applications
for a stub that is physically 0.1 WL long instead of 0.25WL?

It could be shortened even more by using 600 ohm line with
50 ohm line. On top of everything else, the current in the
50 ohm section seems to be much lower than the current in
the 600 ohm section thus reducing the losses in the stub.

From these experiments, I have concluded that the phase shift
in a 75m mobile loading coil may be in the ballpark of 20 degrees
while the phase shift in the stinger is in the ballpark of 20
degrees with the majority of phase shift coming from the
impedance discontinuity between the loading coil and the stinger.
So neither side of the years-long argument was right or wrong.
--
73, Cecil http://www.qsl.net/w5dxp


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