The ATU, a dying art?
 

wrote in message
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On Thursday, February 13, 2014 4:29:12 AM UTC-6, gareth wrote:
wrote in message
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Myself, I find the whole topic as kind of silly. And to drag the
poor CBer's into it, even more silly.

The topic is a very serious one, the decline of amateur radio to
become indistinghuishable from CB radio, save for a few extra
bands, etc, and the arrival on the scene of auto tuners in danger
of being one of the last nails in the coffin.

Says who? You? Auto tuners have been around for years and years,
and have nothing to do with the state of Amateur Radio.
Amateur Radio is declining because is a lack of overall interest,
and the use of the internet for instant global communications.
Among other things.. But trust me, ATU's have nothing to do with it.

Says who? You?

The ATU, a dying art?
 

On Thursday, February 13, 2014 5:26:11 AM UTC-6, gareth wrote:


Among other things.. But trust me, ATU's have nothing to do with it.



Says who? You?

Yea, me.

The ATU, a dying art?
 

On Wednesday, February 12, 2014 9:55:39 PM UTC-6, Jeff Liebermann wrote:
Did you ever reach a conclusion or a consensus?

I reached a conclusion based on the inductance calculator at:

http://hamwaves.com/antennas/inductance.html

When I plug the 75m Texas Bugcatcher loading coil into that calculator, it gives an axial propagation factor of 3.5333 radians per meter. Multiplying by 1.4553 gives a propagation factor of 5.142 degrees per inch. Multiplying by the length of the coil, 6.5", yields an electrical length of 33.4 degrees. At 4 MHz, the propagation delay would be 23.2 ns. Because the loading coil is used in a standing wave antenna, the standing wave phase delay and traveling wave propagation delay are unrelated, i.e. a phase delay measurement will not yield the correct propagation delay or number of degrees occupied by the loading coil during normal transmit operation.

Since the complaint was that hams are not technical enough, I thought I would introduce a technical subject and see what happens.:)
--
73, Cecil, w5dxp.com

The ATU, a dying art?
 

"gareth" wrote in message
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An interesting poser. I do remember in my final year at Uni in 1972
touching on delay lines fabricated from L & C, ubt have not
encountered the phenomenon for the past 42 years.

That sounds like a VERY long delay line!
--
;-)
..
73 de Frank Turner-Smith G3VKI - mine's a pint.
..
http://turner-smith.co.uk

The ATU, a dying art?
 

"arthur c. grindhouse" wrote in message
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can you point us in the direction of this decline you say is happening,

Yes. Just research the postings of one John Connelly who has
the CB-like callsign of 2M0SIL.

The ATU, a dying art?
 

"W5DXP" wrote in message
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On Wednesday, February 12, 2014 3:21:49 PM UTC-6, Sal wrote:
I'm at one end of the ham-knowledge scale ...

Sal, what is your technical opinion about the propagation delay through a
72uH 75m mobile Texas Bugcatcher loading coil?
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73, Cecil, w5dxp.com

It's fine with me. I bet that coil works okay and will last a long time.
(I apparently haven't made it far enough along that scale.)

73,
"Sal"
(arrogance now in check, at least for the moment)

The ATU, a dying art?
 

"Sal" salmonella@food poisoning.org wrote in message
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"W5DXP" wrote in message
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On Wednesday, February 12, 2014 3:21:49 PM UTC-6, Sal wrote:
I'm at one end of the ham-knowledge scale ...

Sal, what is your technical opinion about the propagation delay through a
72uH 75m mobile Texas Bugcatcher loading coil?
--
73, Cecil, w5dxp.com

Sorry, I didn't mean to answer this twice. The first answer took a while to
appear and I feared it was gone.

"Sal"

The ATU, a dying art?
 

On Thursday, February 13, 2014 7:19:34 AM UTC-6, W5DXP wrote:
On Wednesday, February 12, 2014 9:55:39 PM UTC-6, Jeff Liebermann wrote:

Did you ever reach a conclusion or a consensus?



I reached a conclusion based on the inductance calculator at:



http://hamwaves.com/antennas/inductance.html



When I plug the 75m Texas Bugcatcher loading coil into that calculator, it gives an axial propagation factor of 3.5333 radians per meter. Multiplying by 1.4553 gives a propagation factor of 5.142 degrees per inch. Multiplying by the length of the coil, 6.5", yields an electrical length of 33.4 degrees. At 4 MHz, the propagation delay would be 23.2 ns. Because the loading coil is used in a standing wave antenna, the standing wave phase delay and traveling wave propagation delay are unrelated, i.e. a phase delay measurement will not yield the correct propagation delay or number of degrees occupied by the loading coil during normal transmit operation.



Since the complaint was that hams are not technical enough, I thought I would introduce a technical subject and see what happens.:)

--

73, Cecil, w5dxp.com

Is this related to the great K3BU-W8JI "current across the coil" debate?
Seems some came to the conclusion that the location of the coil had a
lot to do with whether the current was equal at each end of the coil..
IE: in one exact location it could be equal, but in other locations it
could vary at each end.

I forgot now, it's been so long.. I never really worried about it too
much, because even if it were proven that the current dropped across
the coil, it would not change the design of the antenna.
Just more along the lines of something to know or keep in mind.

The ATU, a dying art?
 

On Thursday, February 13, 2014 11:09:51 PM UTC-6, wrote:
Is this related to the great K3BU-W8JI "current across the coil" debate?
Seems some came to the conclusion that the location of the coil had a
lot to do with whether the current was equal at each end of the coil..
IE: in one exact location it could be equal, but in other locations it
could vary at each end.

It is related. I wasn't trying to revive the debate - just trying to pick
Sal's brain for his technical opinion.

The total current in a 75m loading coil, like any other standing wave
antenna, is primarily a function of the superposition of the forward
current and reflected current. The total current is highest when those
two currents are in phase and lowest when those two currents are 180
degrees out of phase. The actual energy decrease in current is minor
compared to the effect of phasing. One can assume zero energy decrease
in the individual forward and reflected currents and still be very close
to the measurements of the actual total current.

Strangely enough, both sides of that argument were half-right and
half-wrong. K3BU's argument that the coil replaced all of the missing
part of the antenna was about half right. W8JI's argument that a
phase shift between the top of the coil and the stinger was responsible
for all of the missing part of the antenna was about half right.
--
73, Cecil, w5dxp.com

The ATU, a dying art?
 

"gareth" wrote in message
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"gareth" wrote in message
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I am not ducking the question but before I answer it, I seek some
reassurance
from you that you are going to behave in the manner that is expected from
a grown-up
in an international debating forum.
You seem to be ducking such a reassurance.
Hullo? Connelly?


HULLO CONNELLY?

Do you wish to engage me in a civil, adult conversation, or are
you happy with the perception that you behave as does a CBer?